P0152 and oxygen sensors

May 13, 2013, 7:57 am

≪ Previous: Stalls and restarts after cooldown, P0230, U0100, GM truck

P0152 and oxygen sensors
Trouble code P0152 Oxygen Sensor Circuit High Voltage (Bank 2 Sensor 1) is a fairly common code. And like all trouble codes, just because the sensor’s name is part of the description, that DOESN’T automatically mean the sensor is bad. In fact, the sensor could be telling the truth and the real problem might be, and often is, a vacuum leak or a leaking fuel injector. So do your testing before you automatically throw in a new oxygen sensor.

P0420, P0421, P0422, P0423, P0424, P0430, P0431, P0432, P0433, P0434

Oxygen Sensor

Speaking of oxygen sensors, you’d better get used to the new technology. The new sensors are called Wideband Oxygen Sensors, Wide Range Air Fuel (WRAF) sensors, or Air/Fuel Sensors (A/F). We’re not just talking semantics here. There really is a difference in how these sensors work.

Old style sensors generate their own voltage
Old style oxygen sensors are literally voltage generators. In other words, they generate their own voltage based on the difference between oxygen content in the exhaust stream and oxygen content in the atmosphere. The voltage ranges from 0.1 to 0.95-volt, with the midway point of 0.45-volts acting as the crossover point. If the sensor reports a voltage below 0.45-volts, the PCM interprets that as lean exhaust, anything over 0.45-volts as rich. However, no computer can accurately calculate the correct amount of fuel as the vehicle is moving—there are just too many variables. You’re always moving the gas pedal, the vehicle is going up and down hills and so the fuel needs are always changing. Since the oxygen sensor is located in the exhaust stream, it’s always measuring how well the PCM did calculating air/fuel mixtures. But it’s always after the fact. By constantly varying the fuel injector ON versus OFF times and watching the oxygen sensor cross-counts, the PCM narrows the “window of errors” to achieve an emissions-friendly reading. And, the PCM “learns” from these calculations and adjusts short and long term fuel trims based on that learning process.

Wideband Oxygen Sensors Work Differently
Wideband Sensors are different because they don’t generate their own voltage. They receive input voltage from the PCM. The reference voltage varies depending on car manufacturer (3.3-volts for Toyota A/F sensors and 2.6-volts on Bosch and GM Wideband Sensors are just two examples). Wideband Sensors still see the swing between rich and lean, but they don’t report it to the PCM as cross-counts. Instead, the internal circuitry varies the output voltage to the PCM.

Both have heaters
In order for the sensing elements to respond to oxygen levels, they must get hot. So the sensors include a built in heater coil. Both traditional and Wideband Sensors have a heating circuit. And just like the older styles, the new Wideband Sensors can develop short-to-ground conditions and failed heaters.

Contamination and leaks
Just like old style sensors, Wideband Sensors can also be contaminated by phosphorous from motor oil, coolant, sulfur, and silicone. And, they’re just as easily fooled by exhaust leaks that allow atmospheric air to enter the exhaust stream.
When a wideband O2 sensor or A/F sensor fails, the symptoms appear almost the same as a conventional oxygen sensor: The engine may run rich, get poor fuel economy and generate higher than normal levels of carbon
monoxide (CO) in the exhaust.

And the causes of the problem may be the same as well–bad wiring connections or a faulty heater circuit relay or a wiring fault, leaky exhaust manifold gasket or leaky exhaust valves.

Most pros check sensor operation with a scan tool. But there are some checks you can perform with a digital voltmeter. For example, you can connect a DVOM multimeter in series with the sensor’s voltage reference line (refer to a wiring diagram for the proper connection). Connect the black negative lead to the sensor end of the reference wire, and the red positive lead to the PCM end of the wire. The meter should then show an increase in voltage (above the reference voltage) if the air/fuel mixture is lean, or a drop in voltage (below the reference voltage) if the mixture is rich.

Be aware:

Honda’s 5-wire “Lean Air Fuel” (LAF) sensor contains a special calibration
Resistor in the connector. If the connector is damaged or contaminated with oil the resistance value will be off.

Saturn also uses a resistor in their wideband O2 sensor connector (pins 1 & 6). The resistor is typically 30 to 300 ohms. The PCM supplied reference voltage is 2.4 to 2.6 volts.

If an O2 sensor, wideband O2 sensor or A/F sensor fails due to coolant contamination, do not replace the sensor until you repair the root cause, or the new sensor will suffer the same fate.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

For more information on this repair or any others for your vehicle, buy an online subscription to either Alldatadiy.com or eautorepair.net. Click on this link to compare the two services: Compare Alldata and Eautorepair.

If you just need information for a single repair and want to save money,eautorepair offers a lower price 1-week subscription for only $11.99. Or, if you’ll be working on this vehicle in the future, you can buy a 1-year subscription (Alldatadiy.com for $26.99, or eautorepair.net $29.99)

Alldatadiy.com

eautorepair.net

Alldata and Eautorepair are both professional grade shop manuals. You’ll find more in-depth information and more complete wiring diagrams, along with descriptions of how the systems work. And, you’ll get all that at a price you can afford. Check them out!

Click HERE to read AUTO REPAIR ARTICLES sorted by topic
Click HERE to read some cool DIAGNOSTIC TIPS
Click HERE to read ACURA articles
Click HERE to read AUDI articles
Click HERE to read BMW articles
Click HERE to read CHRYSLER articles
Click HERE to read DODGE articles
Click HERE to read FORD LINCOLN MERCURY articles
Click HERE to read GM articles
Click HERE to read HONDA articles
Click HERE to read HYUNDAI articles
Click HERE to read INFINITI articles
Click HERE to read JEEP articles
Click HERE to read KIA articles
Click HERE to read MITSUBISHI articles
Click HERE to read NISSAN articles
Click HERE to read SUBURU articles
Click HERE to read TOYOTA articles
Click HERE to read VOLKSWAGEN articles

↧

P0551, Dodge trucks

May 15, 2013, 5:00 pm

≫ Next: C0561 traction control code

≪ Previous: P0152 and oxygen sensors

P0551, Dodge trucks

If you own an early 2000 Dodge Dakota, Durango, or Ram and have a check engine light and trouble code P0551, head right for the power steering pressure switch located in the high pressure power steering hose. This sensor has a high failure rate. Worse than the fact that it leaks, the diaphragm inside may actually tear and force full pressure power steering fluid up through the wiring harness and down into the oxygen sensor wires. That can cause a P0171 lean condition. When the two codes happen at the same time, you may not make the association. But they are usually related. The only fix is the replace the switch and clean the wiring harness. Since the fluid has most likely seeped between the insulation and the copper wire on the oxygen sensor ground, it’s best to cut the black ground wire and splice in a new ground.

However, if you don’t find leaking fluid, the sensor may actually be telling the truth, in which case you may have a power steering pump problem. Since most of you guys won’t have a high pressure gauge to test line pressure, I recommend replacing the sensor as a first step since its far less costly than a pump. If the new sensor still trips the P0551 code, check out the pump and the fluid reservoir to make sure the pump is getting a full supply of fluid

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

C0561 traction control code

May 16, 2013, 4:25 pm

≫ Next: C0561 service bulletin

≪ Previous: P0551, Dodge trucks

C0561 traction control code

Code C0561 comes in two forms.

C0561-71 System disabled Information stored invalid serial data received
C0561-72 System disabled Information stored alive counter incorrect.

C codes are considered “chassis” code. This particular code is for GM and relates to the traction control system. The traction control system gets its data from the ABS system. When it detects one wheel spinning faster than the others, or one wheel locking up, it activates the traction control system. Depending on the generation of traction control, the system will activate the ABS brakes to reduces spinning, or, in later models can actually reduce engine power. Late model systems include yaw sensors and steering position sensors to detect the difference between the driver’s intention from the steering wheel and the actually direction the vehicle is moving.

In the case of this GM code, the electronic brake control module (EBCM) is what disables the traction control system or the vehicle stability enhancement system.

The code means the EBCM is receiving faulty data from other modules or is faulty itself.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

C0561 service bulletin

May 16, 2013, 4:37 pm

≫ Next: Brake pedal pulsation or vibration

≪ Previous: C0561 traction control code

C0561 service bulletin

GM has issued a service bulletin (PIC5074B) to address a C0561 trouble code on the following vehicles:

2008-2012 Chevrolet Malibu
2008-2009 Pontiac G6
2008-2009 Saturn Aura

GM advises to check for all other codes that may be stored and address those first. GM has discovered that the most common cause of the C0561 code is a faulty traction control switch assembly. However, before replacing the switch, GM suggests checking the body control module to make sure it’s activating the traction control on and off like it should.

Be aware that the system depends on ABS and traction control systems rely on digital data and any short or malfunction in other modules can interrupt or corrupt the data lines.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

Brake pedal pulsation or vibration

May 18, 2013, 7:00 pm

≫ Next: Chrysler charging systems

≪ Previous: C0561 service bulletin

Brake pedal pulsation or vibration

Chrysler has issued a Technical Service Bulletin (TSB) 05-002-13 dated Feb 22, 2013 to address a brake pedal “judder” or vibration on 2011-2012 Caravan and Town & Country vehicles. The repair applies to vehicles with brake code BRE or BRG and built before March 30, 2012. The repair involves installing new brake pads, new rotors (or resurfacing the existing rotors) and replacing the lower control arms. The newest rotors are part # 04779783AB. The revised front right control arm is part #04766910AK and the left front is 04766911AK. The new brake pads are part 68093323AB.

If you have an approved on-vehicle brake lathe and the rotors meet Chrysler’s resurfacing specifications, resurface the rotors. If you do not have the proper brake lathe, replace the rotors with the new part numbers.

Next, remove the lower control arms and inspect the bushings. If the bushing have 8 slots as shown in the photo 2, along with a plastic inner substrate, your vehicle has the most current bushings. If your bushings have 3 slots and a metal substrate as in photo 1, replace the control arms with the new style.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

Chrysler charging systems

May 20, 2013, 9:35 am

≫ Next: P0137

≪ Previous: Brake pedal pulsation or vibration

Chrysler charging systems

The manner in which Chrysler charging systems power the alternator field varies depending on which generation PCM you have installed in your vehicle. So consult a shop manual for the exact system used in your vehicle. This is just an overview.

In a Next Generation Controller PCM the alternator has 3 wires. The black wire is a contact ground. The PCM sends a pulsed power to the alternator field coil on the dark green wire. The strength of the field depends on the pulse width. The output to the battery is on the black/grey wire.

Here’s how this system works. Depending on the engine size, the PCM needs to determine the temperature of the battery before figuring out the charge rate. On the 2.0-litre engine, it uses a battery temperature sensor located under the battery or in the battery blanket. On the 1.6-litre engine, it calculates battery temperature by looking at the intake air temperature sensor, engine coolant temp sensor, vehicle speed sensor, and radiator fan state. Rather than install a freaking battery temp sensor, Chrysler has decided to calculate battery temp based on how fast the vehicle is traveling, whether the radiator fan is blowing air across the battery, the outside air temp, etc. If any of these sensors are bad, it can set off the alternator light.

The battery temp sensor has a high failure rate because it’s situated closed to battery acid. If you own a 2.0-liter engine and have replaced the alternator and still have a charging issue, check the battery temp sensor and the connector. You’re looking for corrosion in the connector, or a failed sensor.

Also check the field ground wire. The alternator field ground wire goes through two connectors and three splices before it terminates at ground (great engineering Chrysler). Any corrosion or break in the field ground will affect alternator output.

Finally, check the output connections to the battery.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

P0137

May 31, 2013, 9:26 am

≫ Next: Engine failure after valve job Audi and Volkswagen 1.8-liter

≪ Previous: Chrysler charging systems

P0137

Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 1). This sensor is located on the engine bank that houses #1 cylinder and is located AFTER the catalytic converter

The PCM sends a reference voltage (usually 5-volts) to the variable resistor in the oxygen sensor and looks for a return voltage. Once the sensor is heated up, the PCM expects to see a varying voltage. If the PCM sees a constant low voltage, it will set a trouble code P0137.

Most common causes are: vacuum leak that’s allowing too much unmetered air into the combustion chamber and causing lean misfires, bad oxygen sensor, poor connection either at PCM or O2 sensor.

TEST: Very difficult to test without either scope or scan tool. The most effective way to determine if you have a vacuum leak is to examine the fuel trim reading on a scan tool. If you have a vacuum leak and the sensor detects a continuous lean exhaust condition, the PCM will add fuel to compensate. Fuel trim should be as low as possible, but never approaching 25%. That would indicate a vacuum leak.

To learn how to replace an oxygen sensor, click here

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

Engine failure after valve job Audi and Volkswagen 1.8-liter

May 31, 2013, 9:28 am

≫ Next: Oil light on

≪ Previous: P0137

Engine failure after valve job Audi and Volkswagen 1.8-liter

If you’ve had a valve job on your Audi or Volkswagen 1.8-liter engine and then encountered catastrophic engine failure, the blame may rest with the shop doing the work.

Audi and Volkwagen have investigated the engine failures and found that the shops were not following official recommendations.

First, Audi and Volkswagen recommend new hydraulic lifters when doing a valve job. If the shop reuses the oil ones, they must be thoroughly cleaned, refilled, and properly adjusted. Any contamination in the lifter metering device can cause the valve to contact the piston. On installation, the lifter and cam lobes MUST be coated with an extreme pressure grease. New oil MUST be used in the engine on startup.

The manufacturers warn that the new lifters must be allowed to settle in the head for 30 minutes after installation. Ideally, the engine should sit overnight. That allows excess oil to drain. If the shop did not allow that settling time, the lifter can cause the valve to open too much and contact the piston. After settling, the shop must rotate the engine BY HAND for two complete engine cycles to make sure the valves aren’t contacting the pistons. If the shop skips this step, the engine will suffer immediate failure.

Finally, Audi/VW recommend replacing all the valve keepers instead or reusing the old ones. The valve stems on these engines are so small, that any wear can cause the valve to not seat properly.

↧

Oil light on

June 2, 2013, 11:56 am

≫ Next: No start, hard start, Saturn Relay

≪ Previous: Engine failure after valve job Audi and Volkswagen 1.8-liter

Oil light on

All engines are equipped with an oil pressure sensor, also called a sending unit. If the vehicle has a gauge, the sending unit sends a varying voltage to the gauge. But if the vehicle just has an oil light, the sending unit lights the light only when oil pressure is below specification. That’s why the oil light is on at startup when oil pressure hasn’t yet built up to spec. Once pressure reaches the minimum level, the light goes out.
If the oil light doesn’t go out, there can be three causes; either the sending unit has developed a leak (externally or internal) and is outputting a bad signal, the engine is dangerously low on oil, or the engine really is low on oil pressure.
A shop would remove the sending unit and connect an oil pressure gauge to get an exact reading. You probably don’t own or have access to a gauge, so your best bet is to try a new oil sending unit. They’re pretty cheap, less than $20. But you usually need a special socket to swap out the sensors. Most auto parts stores will rent the socket. Or you can click here to buy one. If the light goes out and stays out with a new sensor, you’ve found the cause and fixed the problem.
However, if the light stays on with the new sensor, you’ve got a far more serious problem. The low pressure can be due to a worn oil pump, worn bearings, a clogged pickup screen, or a leak somewhere in the system. A shop would install a pressurized tank of oil and connect it to the oil pressure sending unit port. Then they’d remove the oil pan and examine the drip rate from the bearings. Excessive drip would indicate worn bearings.
Most DIYers, on the other hand, start by replacing the pump. But keep in mind that if the pump has suffered that kind of wear, so have all the bearings. A worn pump is a sign of poor maintenance. So don’t get your hopes up that the new pump will fix your low oil pressure problem. Of course, if you don’t have the equipment to diagnose the problem and you know how to drop the oil pan and replace the pump, you have little to lose but time and money. Just don’t forget to pack the pump with grease to prime it. That’s the most common DIY mistake. A dry pump will not prime itself.
If you determine that the low pressure is caused by excessive bearing clearances, you’ll have to make the decision on whether to rebuild or replace the engine. Whichever you decide, use this as a learning experience that poor maintenance always causes excessive wear. You never save money by skimping on oil changes.

Finally, don’t confuse an oil pressure light with an oil LEVEL light. Few cars have oil level sensors. If yours does, it means the engine is dangerously low on oil. Pulling over and turning off the engine should be your first course of action when either light comes on. If the oil level is low, fill it up to the full line. The light should go out. If it does, you can keep driving. But if the light stays on, call a tow truck. Driving with the oil light on can cause total engine destruction.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

No start, hard start, Saturn Relay

June 5, 2013, 8:47 am

≫ Next: P0441, P0455, P0456, Lexus

≪ Previous: Oil light on

No start, hard start, Saturn Relay

If you own a 2005-07 Saturn Relay minivan and experience hard starting or can’t start it at all, this may be the fix for you. In addition, you may experience an inoperative fuel gauge, along with a check engine, ABS, TCS, Service Traction System, or All Wheel Drive Disabled warning light(s).

It may appear your vehicle is possessed. But there is a common link with all these problems. You’ll find it at connector C305 located on the floor under the driver’s seat. Open the connector and look for corrosion. If you see any, find out where the water is coming from and fix that first. Then treat the electrical connections with an anti-corrosion cleaner and coat with dielectric grease. If that doesn’t work, replace the connector. If the connectors are spread, don’t try to bend them. Instead buy a terminal replacement kit and replace each one.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

P0441, P0455, P0456, Lexus

June 5, 2013, 8:52 am

≫ Next: Central Timer Module, body control module, gem module

≪ Previous: No start, hard start, Saturn Relay

P0441, P0455, P0456, Lexus

If you own a 2005-09 Lexus vehicle and have any of these evaporative emissions-related codes, you may be in for a simple fix. Lexus has identified a faulty gas cap as the most likely cause. Replace your gas cap with a redesigned unit, part #77300-47010. If the cap doesn’t fix the problem, then you have to dig deeper. But this is the least expensive way to start.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

Central Timer Module, body control module, gem module

June 8, 2013, 6:15 pm

≫ Next: Synthetic oil versus dino or mineral oil

≪ Previous: P0441, P0455, P0456, Lexus

Central Timer Module

Every car maker is switching to digital controls for almost all vehicle functions. It’s an effort to reduce wiring costs and complexity, reduce weight, and have complete control over all systems to further increase MPG. To understand how the system works, take everything you know about switches and wiring and throw it out the window.

In a digital vehicle, switches are nothing more than signal inputs to a computer. They do NOT switch power. Want to turn on your headlights? The switch gets a low voltage reference voltage from a body control module (BCM). When you turn the switch, it grounds the reference signal. The BCM sees the voltage drop to 0 or near zero (depending on how much voltage drop is in the circuit). Depending on the level of digital complexity, the BCM can provide ground to the control coil on the headlight relay. Or, it can send a digital signal onto the digital bus. In the case of Chrysler, the digital bus connects to the Integrated Power Module (IPM) or Totally Integrated Power Module (TIPM). The TIPM receives the signal and activates either an electro-mechanical relay or a solid state relay.

GM calls their BCM a body control module. Ford calls theirs a Generic Electronic Control (GEM) module. Chrysler calls theirs a Central Timer Module (CTM). In the case of Chrysler, and depending on the vehicle and trim package, the CTM can control the following systems:

Battery Saver Functions For Exterior and Interior Lamps
Cargo Lamps
Chime Warning
Courtesy Lamps
Dome Lamps
Dome Defeat
Door Ajar Switch Status
Fog Lamps
Head Lamp Time Delay
Intermittent Wiper Controls
Low and High Beam Head Lamps
Optical Horn
Park Lamps
Central Locking (VTSS)
Door Lock Inhibit
Driver Door Unlock
Enhanced Accident Response
Power Door Locks
Remote Radio
Remote Keyless Entry
Vehicle Theft Alarm (VTSS)
Horn Chirp
Optical Chirp

The Central Timer Module is located behind the left side kick panel. It is a high failure item. However, before you replace a BCM, make sure the digital bus isn’t shorted. Sometimes a module on the bus can short and place voltage onto the bus. That screws up all digital communications results in all kinds of crazy behavior. Also, since the BCM relies on monitoring low voltage reference signals to the switches, any corrosion can also screw things up. So make sure you check the condition of the connectors before replacing an expensive module.

Finally, most BCMs must be programmed by the dealer or a shop equipped with the proper scan tool. You CANNOT take a BCM from a similar vehicle and slap it into yours. It must be programmed to your exact VIN. In most cases, you’ll also have to reprogram your remote key fobs and keys.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

Synthetic oil versus dino or mineral oil

July 5, 2013, 1:17 pm

≫ Next: P2098 trouble code on Dodge Stratus, Sebring

≪ Previous: Central Timer Module, body control module, gem module

Should you switch to synthetic oil?

This discussion is a bit long, but I’m devoting a lot to it because there are so many myths and legends out there. I’ll cover this topic from A-Z so you can make an informed decision.

What is oil?

All engine oil is built with a base oil (about 80% of the volume) and additives. So let’s start with a discussion of base oil.
Base oils are categorized in six groups. Groups 1-3 are considered traditional mineral oils derived from petroleum crude oil. The refining process removes most of the wax and nitrogen. Then the refining process separates out the remaining unsaturated hydrocarbons and converts them into more stable saturated molecules. Group 1 is the lowest quality oil and converts crude using a solvent extraction process. Group 2 and Group 2+ are considered higher quality and use “hydro-processed” and “Hydro-cracking,” methods respectively. Group 3 oil is the highest level you can attain using traditional petroleum crude as the base material. It’s refined using a “Severe Hydro-cracking” or “Hydroisomerization” method. Since it is such a high quality mineral oil, some oil manufacturers can blend in a bit of Group 4 base and high quality additives and are allowed to call it synthetic. Group 4 oils are made by chemical reaction from Polyalphaolefin (PAO) often derived from natural gas. Most high quality synthetic oils are made with Group 4 base stocks. Group 5 oils are made from synthetic esters, including diesters, polyolesters, alklylated napthlenes, alkylated benzenes, etc.).
Next, the base oils are combined with the oil manufacturers’ unique blend of additives. They include:

Detergent to clean deposits formed by decomposed oil and combustion contaminants
Dispersant additives that keep the contaminants in a fine suspension and prevent them from settling out until they can be filtered out by the oil filter. Dispersants also help prevent sludge formation.
Rust and corrosion inhibitors- protect the engine from water and acids formed by the combustion process
Antioxidants- inhibit the oxidation process. As engine oil oxidizes, it thickens and forms sludge.
Anti-wear additives form a film on metal surfaces to help prevent
metal-to-metal contact
Viscosity modifiers (VM)- a polymeric additive, where the molecules are smaller and wound tighter when cold and unwind and expand like a clock spring when hot. In effect the VM molecules thicken the oil.
Pour point depressants (PPD)- All mineral oil contains some wax to improve lubricity. But the wax molecules can inhibit flow when cold. So pour point depressants, help the oil flow better when cold.

Now a discussion of viscosity and multi-viscosity

Viscosity is an oil’s resistance to flow and shear (when molecules are cut apart). Cold oil has more resistance to flow. Manufacturers can make traditional mineral oil flow easier by adding a pour-point depressant to prevent wax particles from coalescing together and restricting flow when cold. True synthetic oil (made with Group 4 base oil) doesn’t have any wax. When cold, the uniform molecule size makes the oil flow better when cold. So it has a naturally low pour point. In fact, they have excellent pour points all the way down to -50°F.
Oil viscosity can be measured several ways. One common method is to fill a small container with a precise amount and let it flow through a specific opening and time how long it takes to empty the container. This is called Kinematic Viscosity and is measured in centistokes (cSt). One cSt is defined as a fluid that moves at 1-mm2/second. At 68°F, water measures 1 cSt, 20-weight engine oil is 4.3 cSt, and sour cream is 19,000 cSt.
But engine oil is pumped through small channels, not gravity fed through an opening. As oil flows through a narrow channel it incurs internal friction as the molecules are forced closer together and ride against the walls of the channel. So viscosity must also be measured as the oil flows through a narrow opening. This testing method is called Dynamic or Absolute Viscosity and is measured in centiPoise (cP).
High Temperature High Shear (HTHS) is a rating of an oil’s resistance to flow between fast moving parts in a fully warmed engine. You’ll find this condition between rotating parts and their bearings, like crankshaft and camshafts, and camshaft and hydraulic lifters. An oil’s HTHS rating has a direct impact on fuel consumption, valve-train wear, and bearing protection.

Here’s a chart to illustrate. It shows Dynamic/Absolute Viscosity in the first column, followed by Kinematic Viscosity (gravity flow) in the second and HTHS in the third column. Cold cranking represents how oil behaves in a crankshaft bearing on a cold winter’s morning. It doesn’t take much brain power to realize that a high viscosity oil will slow down cranking speed and make it even harder to start a cold engine. So these figures represent the lowest temperature at which an engine can start with each viscosity oil. Maximum cold pumping, on the other hand, shows the maximum viscosity at which an engine oil pump can actually pump oil at a given temperature. If the pump can’t pump the oil, you won’t have sufficient lubrication during a cold start. Worse yet, all engines run at a faster idle speed at cold startup, so you experience a double-whammy where you not only don’t have lubrication, but you’re running parts at a faster speed. Talk about cold start wear! All SAE tests are conducted in Centigrade, but I’ve converted those to F so they’re easier for us Americans to understand.

Now let’s talk about multi-viscosity oil

Traditional mineral multi-viscosity 10W-30 oil is made from 10-weight base oil. The manufacturer adds enough Viscosity Modifiers (VM) to make the 10-weight oil behave like a 30-weight oil when hot. The polymeric additives literally uncoil and thicken the oil to flow like 30-weight. There are other ways to build a multi-viscosity oil, but I’m keep this as simple as possible.
Multi-viscosity 10W-30 synthetic oil, on the other hand can be made from 20-weight oil that flows like 10-weight oil when cold. The manufacturer adds far less VM to make it thicken up to 30-weight when hot. Each oil manufacturer has their own recipe to achieve multi-viscosity performance. This is just one example.
No matter which brand you choose, keep in mind that VM additives break down under shear and heat loads. So hauling a heavy load will breakdown your oil faster than dropping off the kids at school.
Viscosity Index is another factor you should consider. Think of VI as the range the oil covers. In the ‘70’s car makers recommended 10W-40 oil as the one-size-fits-all oil. It was a mineral oil built on 10-weight with enough VM added to build viscosity up o 40-weight. But that’s a LOT of polymeric additive. As the additive molecules sheared, they degraded and formed deposits on the piston rings causing them to stick in the lands. You’ll notice that most new car makers now recommend a much tighter VI, like 0W-20, or 5W-20.

Does synthetic oil last longer? Can I extend my oil change intervals?

Not a single oil manufacturer is willing to go out on a limb and say yes to this question AS LONG AS YOU’RE COVERED BY A WARRANTY. Get it? If you extend oil changes and experience an oil-related engine failure, the car maker or the extended warranty company will deny your claim. Once you’re out of warranty, it’s a different story.
The answer depends on how you drive. Synthetic oil is a better lubricant than mineral oil, but it’s not a magic potion. It still has to lubricate, carry heat away from metal parts, clean your engine, and prevent sludge and corrosion. And the life of synthetic oil and its additives depends STRICTLY on how you drive. If anyone gives you a flat mileage figure, they’re selling snake oil, not engine oil.
If you make lots of short trips in stop and go traffic, you’ll get more fuel dilution in the oil and you won’t run the engine long enough to burn it off. That’ll increase the load on the acid neutralizer additives. Or, if you leave your car outside in the winter, start it up and drive away, you’ll use up the anti-wear additives faster. If your engine has high miles, you’ll have more blowby gasses in the crankcase and that’ll cause the dispersants and detergents to deplete.
So you tell me, can anybody give you a pat answer on how long the oil will last? Nope.
Some oil companies encourage users to conduct oil testing to determine when it’s time to change oil. I’m not a big fan of that method. First, when you add up the costs of the tests, you’ll spend more than just doing an oil change on an earlier schedule. Second, not all labs use the same testing methods or test for the same properties. Most labs do test for the presence of anti-wear additives and metal molecules that would indicate wear. But what about the other additives?

Can you depend on the Service Oil Light?

That depends on which method the car maker employs. Some lights go off at specific mileage intervals. As you can see from above, that’s not a very reliable way to predict oil condition. But, it’s better than no reminder at all.
Newer vehicles use a far more sophisticated method. GM, for example, specifies a certain oil, DEXOS for their engines. Oil makers that license the DEXOS name must comply with GM’s formula. That means GM knows how much of each additive is in the oil. The oil life monitor computer tracks the number of times you start the engine and what the engine temperature is. It also tracks the loads you place on the engine and the RPMS. Knowing all that, the GM Oil Life Monitor can predict oil life based on your particular driving conditions.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

P2098 trouble code on Dodge Stratus, Sebring

July 6, 2013, 1:49 pm

≫ Next: How to change your battery

≪ Previous: Synthetic oil versus dino or mineral oil

P2098 trouble code on Dodge Stratus, Sebring

Trouble code P2098 on a Dodge Sebring or Dodge Stratus indicates that the downstream (post catalytic converter) is reporting a reading that’s consistently above or below center for a predetermined amount of time. Most DIYers replace the oxygen sensor and wonder why they still get the same code. In effect they’re treating the messenger and not the message.

An exhaust system has two oxygen sensors. The first sensor tests how well the computer did in calculating air/fuel mixture. The second sensor tests how well the catalytic converter

Cut-away of a typical catalytic converter

did its job in cleaning up emissions. The pre-cat sensor should reports rapid fluctuations between rich and lean, as the computer is constantly trying to correct air/fuel mixtures for all RPMs. But the post cat sensor should have very few fluctuations, showing that the catalytic converter has cleaned up the exhaust.

If the computer detects NO fluctuations in the post catalytic converter sensor, it’ll purposely force rich/lean conditions to get a reaction from the post cat sensor. However, if there’s a vacuum leak, exhaust leak or a fuel system problem, the post cat sensor can stay above or below the centerline. If the reading stays above or below past a predetermined amount of time, the computer will set P2098.

Keep in mind that an oxygen sensor fails in fairly predictable ways. If it’s contaminated with coolant, silicone, or oil, the substance will clog the pores of the sensor and it will report NO oxygen. In other words, it’ll report a dead signal. If the pores are partially clogged, the sensor will not switch between rich and lean very quickly. This is known as a “lazy sensor.” But one thing a bad sensor will never do is report a consistent above or below center as this code indicates. So if you replaced the sensor to fix a P2098, you were chasing the wrong squirrel.

A shop would connect a scan tool and check for increased fuel trim. That’s extra fuel that the computer is commanding to make up for a vacuum leak. If they see that, they’ll hunt for a vacuum leak or a leak in the air duct between the MAF sensor and the throttle body. If they don’t find a vacuum leak, they’ll check for an exhaust leak. An exhaust leak would suck outside air into the exhaust during deceleration, causing the post cat sensor to report above or below center. If that checks out, they’ll look for a fuel or mechanical problem.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

How to change your battery

July 7, 2013, 8:34 am

≫ Next: P0133, P0139, P0170, P0173, P0171, P0174, P1136, P1138, P1141, P1143, AUDI, VOLKSWAGEN

≪ Previous: P2098 trouble code on Dodge Stratus, Sebring

How to change your battery

Late model vehicles include many fly-by-wire systems. For example, the accelerator pedal no longer connects to the throttle body with a cable. It’s wired into the PCM and the PCM controls a stepper or servo motor on the throttle body. When properly programmed, the PCM knows when the throttle plate is fully closed and fully open. But if you change your battery without providing supplemental power to the PCM, it can “forget” those settings. Some vehicles will relearn them on their own after a battery change, but others require a scan tool relearn procedure. So changing your own battery using “old school” methods can actually cost you a tow and a minimum shop fee to put your vehicle through a relearn. Yeah, you may think it’s stupid, but, as they say, welcome to the club.

Here’s how to prevent all those problems. You’ll need a jumper pack or an AC-DC power converter, and you’ll need a special OBDII cable. The SOLAR #ESA30 cable is about $9 from amazon.com.

SOLAR #ESA30 cable

And you can pick up a battery powered jumper pack at any auto parts store or WalMart for under $50.

Plug the cable into the OBDII socket with the key out of the ignition. Then plug the cigarette light end into the jumper pack. Next, disconnect the negative battery cable. Then remove the positive cable and INSULATE it—it’s live. I usually throw it inside a leather glove. THEN you can remove the battery.

Clean the posts on the new and the terminals on the cable. Install the positive cable first and then the negative cable. Make it a quick push-on affair—you want to avoid arcing that can damage computers. Once the new battery is in place, you can remove the supplemental power.

This procedure keeps the PCM fully powered up and prevents it from losing all it “adaptive memory.” So you can start the engine and go without the PCM having to relearn all the values.

It’s the computer age and this is just the way it is. So quit your bitchin about how easy it was in the old days before computers. Remember those days—when you only got 10MPG. Oh yeah, they weren’t really as great as you thought.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

P0133, P0139, P0170, P0173, P0171, P0174, P1136, P1138, P1141, P1143, AUDI, VOLKSWAGEN

July 20, 2013, 9:37 am

≫ Next: Service 4WD light on, trouble code C0388, C0374

≪ Previous: How to change your battery

P0133, P0139, P0170, P0173, P0171, P0174, P1136, P1138, P1141, P1143, AUDI, VOLKSWAGEN

If you own an Audi A4, A6, A8, or a Volkswagaen Golf, Jetta, Passat, and New Beetle
With 1.8T, 2.0, 2.8/3.2 VR-6, 2.8 V6 90° or 4.2 V8 engine and have any of the following codes:

P0133 Oxygen sensor: slow response Bank 1
P0139 O2 sensor: slow response, Bank 2
P0170 P0173 Fuel trim malfunction Bank 1/2
P0171 P0174 Bank 1/2 fuel trim lean
P1136 P1138 Bank 1/2 long term trim at lean limit
P1141 P1143 Load calculation cross-check limits

don’t start throwing parts at the problem. Keep this in mind. Every value the computer sees is run through a filter of a sort. For example, before the computer can even compute the air fuel mixture, it must know the outside temperature, the engine coolant temp sensor, the throttle position sensor and must have some indication of barometric pressure.

On older vehicles, the computer used a manifold absolute pressure (MAP) sensor to help it calculate barometric pressure. The computer would look at the reading as you turned the key to on—that would give it atmospheric baro pressure. Then, once the engine was started, it would measure engine vacuum. Since it knew the displacement of the engine, it could calculate absolute baro pressure.

But late model vehicles depend on a mass airflow sensor (MAF). The MAF consists of a wire or plate that conducts an electrical current to heat up. Air flowing across the wire or plate cools it off and the computer measure how much current is required to maintain the wire or plate at a set temperature. Basically, the computer is calculating wind chill. So the computer now knows the temp of the air, the quantity of air, and the mass of the air. That allows it to calculate a much more accurate air/fuel mixture.

However, this all depends on getting an accurate reading from the MAF. Any debris that comes in contact with the MAF wire or hot plate can bake onto it and interfere with its accuracy. If you have a oiled racing filter, for example, the oily fibers from the filter can break away and bake onto the MAF. Even standard cellulose filters can shed fibers. Once the hot wire or hot plate are insulated, they provide inaccurate readings that are detected by the oxygen sensors. A contaminated MAF doesn’t set a check engine codes until the data goes outside a set range. But if the sensor stays within range, it can send faulty data all day long, making you think that the other trouble codes are causing the problem, when in fact, they’re just reporting a symptom of the proble.

So before you even think of replacing any sensors, clean the MAF. Click here for instructions on how to clean a MAF

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

Service 4WD light on, trouble code C0388, C0374

July 25, 2013, 4:52 pm

≫ Next: What oil should you use

≪ Previous: P0133, P0139, P0170, P0173, P0171, P0174, P1136, P1138, P1141, P1143, AUDI, VOLKSWAGEN

Service 4WD light on, trouble code C0388, C0374

General Motors has issued a Technical Service Bulleting #05-04-21-003C to address a problem with their 4WD vehicles where the Service 4WD message may appear. The TSB applies to the following vehicles.

2004–2007 Buick Rainier
2003–2006 Chevrolet Avalanche, Suburban, Tahoe
2003–2007 Chevrolet Silverado Classic, TrailBlazer, TrailBlazer EXT
2003–2006 GMC Yukon, Yukon XL
2003–2007 GMC Envoy, Envoy XL, Sierra Classic
2003–2004 Oldsmobile Bravada
2005–2007 Saab 9–7X with Four Wheel Drive or All-Wheel Drive
and Active All-Wheel Drive (RPO NP4) or Active Two-Speed (RPO NP8) Transfer Case

In addition to the message, you may notice erratic operation of the 4WD or AWD after driving through rain, snow, or a car wash. The cause may be a corrupted speed sensor signal. GM has discovered openings in the speed sensor wiring insulation that may short circuit the signal. This occurs most often on the rear speed sensor.

The fix is the fabricate a new harness or seal the existing harness. Or, for full-size pickup and full-size utility models, replace the pigtail harness that runs from the C151 connector under the hood to the transfer case with harness, 15832722 or 15224663, depending on vehicle equipment.

Another problem with the rear differential lock coil may also cause the message

To diagnose that, disconnect the rear differential lock harness from the rear differential lock coil connector.

Use a digital volt ohm meter (DVOM) and measure the resistance of the rear differential lock coil and pigtail from terminal to terminal.

The resistance should be 2.2-4.3 ohms and not shorted to ground

If your readings are out of spec, replace the rear differential lock coil. Unfortunately, the rear differential side bearing must be removed to replace the lock coil.

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

What oil should you use

August 9, 2013, 5:17 pm

≫ Next: Adding the wrong oil viscosity to your engine

≪ Previous: Service 4WD light on, trouble code C0388, C0374

Choosing the correct oil

On one hand, picking the right oil, filter, and service interval has never been more challenging. Because even if you follow the oil type and viscosity recommendations shown in your owner’s manual, you still have at least a dozen oil formulations to choose from. And oil filters come in just as many flavors. You can buy an expensive $14 filter with the highest dirt holding specifications and the longest mileage rating. On the other hand, picking the correct oil has never been this easy. In fact, the correct oil is listed right in your owner’s manual.
But if you’re here asking the question, that implies that you don’t believe the manufacturer. Really? Do you think the engineers listed an oil viscosity and type just to mess with your head? Or did you think they’re in the pockets of big oil? Wrong!
If you understand the ins and outs of oil, you’d never second guess the car maker. So let’s start by going over the ins and outs.

Oil’s main job is to create a thin cushioning film to separate metal components and prevent contact as the parts rotate and bang against one another. And inside the combustion chamber, the oil film acts as a sealant to close the gap between the piston rings and the cylinder wall and it. That constant sliding, pounding, and shearing friction creates heat. So oil’s second job is to carry away the heat of friction and cool metal parts.
Next, oil has to clean the engine and carry dust, dirt, combustion byproducts (soot and acid), and the remnants of degraded oil off to the filter to be captured. In addition, oil must neutralize acids, prevents metal from corroding, and prevent foaming as whirling parts whip air into it. And it contains anti-oxidants to protect itself against breakdown.
A 5W-20 mineral type oil is really a 5-weight oil with many different sized molecules. The manufacturer blends in a polymeric viscosity improver (VI) additive that uncoils and expands when hot to thicken the oil. So the 5-weight oil behaves like a 20-weight oil. Unfortunately, VI additives break apart under the shearing conditions found in engines.
Synthetic oil is made from mineral oil that’s been broken apart and re-assembled molecule by molecule. The molecules are a uniform size so it pumps easier and faster when cold. Imagine sliding your hand across the ball bearings in each photo and you can see why synthetic oil flows better. The uniform molecules simply offer less resistance. And the uniform size also helps it maintain a strong film cushion when hot.
Generally speaking synthetic oil also contains higher quality additives
Oil does all these things. But first it has to circulate. To do that, it must flow well. And that’s where things get complicated. Thin oil (5-weight) pumps well when cold. But it thins out when hot, making it harder to maintain a cushioning film. Thicker oil (30-weight), on the other hand, maintains a strong cushioning film that doesn’t thin when hot. But it’s almost impossible to pump when cold.
To get the best of both worlds, car makers specify a multi-viscosity oil (5W-30 for example). It’s thin and pumps when cold, but thickens as it heats up. Engineers know exactly what viscosity range is best suited for any particular engine.
In addition to doing all those things, oil also regulates timing and even gas flow. That’s right. If your engine has variable valve timing, the camshafts are advanced or retarded using varying oil pressure in the cam phasers. Use the wrong viscosity oil and you can AFFECT cam timing and set a check engine light. And, if your engine has direct gasoline injection, oil is what pumps the fuel up to 2,000 psi. Use the wrong oil and you can screw up your fuel injection too.

Can you see where this is going?

You’ll get tons of recommendations from people online who will tell you to deviate from the manufacturer’s recommendations and use a heavier weight oil. They’re wrong. Their advice is based on ignorance and myth.

Always follow the manufacturer’s viscosity recommendation.

Aside from neglect, using the wrong oil viscosity is the single most common cause of premature engine wear. And most of that wear occurs during cold starts. What’s considered a cold start? If your vehicle hasn’t run for three or more hours, it’s cold—even if you live in Arizona!
The car maker’s recommendations are in your owner’s manual or right on the oil filler cap. Never second-guess the car maker’s recommendations. NEVER

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

Adding the wrong oil viscosity to your engine

August 11, 2013, 9:24 am

≫ Next: What oil brand is best?

≪ Previous: What oil should you use

Adding the wrong oil viscosity to your engine

I’ve written a post on the importance of using the correct oil viscosity for your particular engine. The take-away from that post is to always use the oil viscosity recommended by the vehicle manufacturer. But another question always seems to come up and it relates to adding oil after the oil change. What happens if you add a quart of oil of a different viscosity to top off your engine? And the answer is pretty simple. If you had 5W-20 in the engine and you add 1 quart of 10W-30, it raises the viscosity of the crankcase oil slightly. One quart won’t change it enough to worry about. It’s the second quart that starts to change the operating characteristics of the oil. So, if you had to add a second quart of a different viscosity, you should change the oil shortly after.

oil filter, wrong oil, do I have to use synthetic

Oil filter filled with sludge

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧

What oil brand is best?

August 13, 2013, 12:24 pm

≫ Next: Fix an air conditioning leak

≪ Previous: Adding the wrong oil viscosity to your engine

What oil brand is best?

I hear this question all the time and people get really emotional with their preferences. But many of the “facts” that get repeated are simply unfounded, out of date, or are based on a misunderstanding of how modern motor oils are made.

The first myth is that because Penzoil is from wells in Pennsylvania, it has too much wax and is no good.

Oil filter filled with sludge

Who knows if that was ever true in the past, but it’s certainly not true now. Some motor oil companies refine their own base stocks and others buy base oil on the open market. But one thing is true, nobody makes base stock from just a single oil well or a single region of the country. Base stock is pretty much base stock. It’s like buying AA jumbo eggs. If it’s grade II or III base stock, it all meets the same standards.

Where brand difference really comes into play is in the area of additives and synthetic. Let’s start with additives. Approximately 75-80% of every quart of motor oil is base stock. Additives make up the rest. And those additives are detergent, anti-foaming, anti-corrosive agents, and suspension agents. Plus, every motor oil contains an anti-wear additive. In addition, muti-viscosity oils contain viscosity improvers (VI), seal conditioners, and pour point depressants. The exact types of additives and the exact recipe for each brand is different and are considered industry secrets. Anyone who tells you that brand X has more anti-wear or better detergent is either blowing smoke, or wants you to believe they have insider information. Yeah, and they have the secret formula to COKE too!

So the bottom line is NOBODY knows what’s in any brand of oil except the oil company’s chief chemist. As long as the oil meets current API standards, it’ll work in your vehicle. Whether one oil works better than another is simply one persons opinion versus another.

For more articles on oil and filters, click here

Got a car question? Click here and send it to me. I’ll do my best to get you an answer.

Alldatadiy.com

eautorepair.net

↧