Westers Garage - Trouble Shooting

General Performance Chip/ECM/PCM Trouble Shooting Chart

OBD2 trouble code chart and diagnostic connector location CLICK HERE

For Complete OBD2 Trouble Code Listings, CLICK HERE

For OBD1-2 "Set Timing" Instructions, CLICK HERE

My starter doesn't engage ...

Read the supplied information carefully after installing the PCM for a quick relearn procedure--pay attention to the passkey information !!

Did you disconnect the battery when installing your chip ?? Recheck your battery connections. Aside from the Corvette and some Cadillac models, there are no other earlier GM calibrations prior to 2001 that use the computer to interrupt the start circuit.

A Ford performance module is impossible to install upside down, and some Ford computers (1998-2000) need to have the J3 segments connections soldered for a complete connection to the ECA processor. Without this repair, the Ford performance chip will not work and the "Theft" light will rapidly flash.

If you supplied us with a calibration number other than what your car originally came with or engine was designed for, your vehicle may not start. If you need the VATS or Passkey disabled, you must tell us this at order time.

For GM FLASH PCM/VCM replacement, the PASSKEY RELEARN PROCEDURE must be done:

The typical 1998+ Car and Truck Passkey/Antitheft relearn procedure is this:

1. Disable your headlamps (Park Brake Apply--do not remove headlamp relay). Attempt to start the vehicle (this means you rotate your ignition key fully to the start position). Vehicle may or may not 'fire' and quit. Some vehicles will not allow starter motor engagement, and this is normal. DO NOT TURN OFF KEY YET !!

2. Leave the key in the "on" position, until the 'security' light goes out or quits alternately flashing between "Security" and "Battery". This relearn period always takes 10 minutes. How long does this take ? 10 minutes. How long do you have to wait ? 10 minutes.

3. After the security light is no longer displayed on the instrument panel cluster, shut the key off ! Wait 5-10 seconds and repeat the above procedure (steps 1 through 3) two more times for a total of 3 start-relearn-attempts, remembering to shut the key off between each 10 minute relearn procedure. This will take 30 minutes--no less. If the 4th start attempt fails to start the vehicle you did one relearn step (or all of them incorrectly). If you left your headlamps on until the battery went dead and voltage dropped below 10.5 volts, no amount of relearn attempts will be learned !!

Don't read too much into this. Most people cannot seem to grasp the simplicity of this relearn procedure.

New for LS2 (2005+)...Here is the GM procedure to relearn the VTD code:

    1. Press the START button.
    2. Observe the Security telltale. After approximately 10 minutes the telltale will turn off.
    3. Turn OFF the ignition, and wait 5 seconds.
    4. Repeat steps 1-3 two more times for a total of 3 cycles or 30 minutes.

               Important !!!

       The vehicle learns the passwords on the ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.

    5. Start the vehicle. The ECM has now learned the RCDLR password.

Make sure there are no bent pins in your ECM connector or pushed out harness pins in the wiring harness. IF a pin has been broken on your ECM, we can repair or replace your ECM/PCM for a small fee.

If this is a new engine installation, carefully check for missing "ground" wiring or an unplugged harness connection.

A performance chip (replacement chip--not replacement computer) will always allow the starter to engage the engine flywheel (with exception of some earlier Corvette calibrations--or 2001+ VCM's), so don't blame a 'chip' on a starter or ignition switch failure.

A freshly painted engine block can inhibit the ground path to the starter...clean those grounds !!

My starter engages, cranking RPM is normal -- but engine will not fire...

Read the supplied information carefully after installing the PCM for a quick relearn procedure--pay attention to the passkey information !!

Did you disconnect the battery when installing your chip ? Even a static discharge can ruin your new calibration. Treat this calibration chip with extreme care. If you also fail to disconnect the battery when swapping chips, the RAM memory retains the values from the previous chip. It will take a long time before new closed loop values are learned. Do not swap chips back and forth without disconnecting the ECM from power, without disconnecting your battery, or without pulling the ECM fuses first.

The second thing to check is if you installed the chip correctly. A GM Prom chip has a notch in one end--it must align to the notch in the carrier as in the supplied instructions. Many people install the chip backwards--this will often damage the chip. A memcal is impossible to install backwards, but with enough force it "could" happen. If the chip is correctly installed and the car still doesn't start--see if the check engine light is rapidly flashing or steadily on--you may have bent a chip "leg" at installation. If you do damage a chip--just send it back to us--we'll immediately send you a new one.

For GM FLASH PCM/VCM replacement, read above PASSKEY RELEARN PROCEDURE :

Make sure there are no bent pins in your ECM connector or pushed out harness pins in the wiring harness. IF a pin has been broken on your ECM, we can repair or replace your ECM/PCM for a small fee.

If this is a new engine installation, carefully check for missing "ground" wiring or an unplugged harness connection, vacuum leak or bad MAF.

A performance chip will always allow the starter to crank the engine (with exception of some Corvette calibrations--or 2002+ VCM's), so don't blame a chip on a starter or ignition switch failure.

New computers need a learn/relearn period. A common trouble code is P1336 or P0315 (Cam/crank sensor position relearn). Sometimes a no-start can occur because the idle has not been learned yet. Read the supplied information carefully after installing the PCM for a quick relearn procedure--pay attention to the passkey information !! We've recently found that some PCM's will not talk to the databuss for a while. Disconnect the battery and let sit for 15 minutes (this is after you've learned the Passkey). Reconnect battery and then reattempt to start.

If no "quick learn" procedure was provided for you, it doesn't need one--simply start the vehicle with 10-15% throttle. Allow to idle. When the idle is stable, put the vehicle in gear with the brake applied. Allow for the idle to stabilize for 20-30 seconds. Return to park. Shut off and re-start to see if the idle is now stable. Repeat if engine is not at operating temperature, and repeat with the airconditioning or high electrical load on (headlamps).

My starter engages, but engine starts and stalls...

Read the supplied information carefully after installing the PCM for a quick relearn procedure--pay attention to the passkey information !!

For GM FLASH PCM/VCM replacement, read above PASSKEY RELEARN PROCEDURE :

My car starts and runs, but idles poorly and the check engine light is on...

Did you remember to install the knock module in your 1994-2000 PCM as instructed ? If so...read further.

Find out what your "trouble code" is and phone or email us immediately. We'll guide you through the diagnostic process or fax you repair information. If you're familiar with OBD1 diagnostics and know how to access trouble codes, good ! If not--give us a call and we'll help you out. Refer to the enclosed sheet that came with your performance chip on how to access the trouble code information. OBD2 (1995 and up import and domestic vehicles) require a scan tool for diagnostic analysis. Check www.autoenginuity.com for some good software/hardware scan tool packages which we endorse. This scanner actually times each scanned event, making it a much more reliable option than some of the other 'scanners' out there.

Some vehicles require a P1336 or P0315 relearn procedure which is performed with a scan tool with bi-directional controls. Most off the shelf scan tools will not do this procedure. Scan tools from OTC, SnapOn or other aftermarket (non-OEM) may or may not perform the procedure properly, either. Do not waste your money on a $200 store bought code reader--this will not help you. A common trouble code is P1336 or P0315 (Cam/crank sensor position error). Sometimes a no-start can occur because the idle has not been learned yet. IF we sent you the computer FROM your vehicle (which you sent us), there should be no CASE relearn procedure or passkey relearn required.

Newly installed computers also need a learn/relearn procedure.

The "idle air control" valve may not have as yet learned it's new position...perform the IAC relearn procedure for GM.

Typical relearn is this:

1. Start vehicle and allow to idle--allow to reach normal operating temperature. Allow to idle in varying gear positions (drive/neutral) for up to 3-5 minutes in each position. Then redo with the A/C on and headlights on ! Some times you may have to coax the idle a bit to maintain an idle--so help it along with the gas pedal !

f no "quick learn" procedure was provided for you, it doesn't need one--simply start the vehicle with 10-15% throttle. Allow to idle. When the idle is stable, put the vehicle in gear with the brake applied. Allow for the idle to stabilize for 1-2 minutes. Return to park. Shut off and re-start to see if the idle is now stable. Repeat if engine is not at operating temperature, and repeat with the airconditioning or high electrical load on (headlamps).

Often, "performance" plug wires cause RFI interference which can corrupt the signals that your computer receives. Many a problem have been solved by simply checking and solving some ignition errors. Check spark plugs for porcelain cracks, broken insulators or incorrect plug gaps. A cracked reluctor in a distributor can actually double the 'tach' pulse, causing a very interesting fuel injection pulse width--again, don't overlook your distributor if so equipped.

A leaking EGR valve is an often discovered problem. This causes lower than normal manifold vacuum, affecting the MAP sensor to ECM readings.

A dirty MAF sensor also causes drivability and idle problems.

Check for an unplugged sensor. Check sensor grounds and sensor supplied voltages. Don't overlook incorrectly installed vacuum lines.

Do not overlook bad grounds, painted mountings or anything that would interfere with good body to chassis connections. Painted bellhousing to transmission surfaces can often lead to early transmission failure or poor electronic communications between the PCM and sensors or solenoids in a transaxle or transmission. Make sure your battery has connections to both engine block and vehicle body on the negative side--and good positive connections where required. A bad tail-light bulb (part of the TCC circuit) can cause early transmission failure in most Ford products--so pay attention to every detail !

Some calibrations or custom hot rods do not use all sensors--if you failed to tell us this, your check engine light will be illuminated.

My car starts and runs, but idles rich or lean...no check engine light.

#1 "rich" problem is a leaking EGR valve. Always check to make sure that this valve doesn't have a leaking pintle and seat--and make sure the EGR solenoid isn't energized (if exists) or that the EGR valve vacuum port isn't being supplied with manifold vacuum. Generic EGR valves are a very poor purchase choice.

#2 "rich" problem is a leaking MAP sensor hose or faulty MAP sensor. Again--simple tests will reveal the problem.

#3 "lean" problem is leaking TBI base gaskets (accompanied by a fast idle and low IAC "counts"). Replace the base gasket where required. Contaminated MAF sensors which improperly measure engine airflow will also incorrectly fuel the engine. This can lead to detonation or very lean operating conditions.

#4 "lean or rich" probem is an O2 sensor that has biased lean or rich. Test to see that the O2 sensor can produce at least 150mV to 900mV. Any leaks ahead of an O2 sensor will slew the computer calibration rich, since the computer will think there's a "lean" problem. Faulty cannister purge solenoids, vacuum leaks, restricted fuel injectors, leaking fuel injectors, leaking fuel pressure regulators, improper PCV valve, leaking MAF boot...etc. -- ALL can cause fuel calibration problems. Please verify before calling. New injectors are often faulty--especially 'performance injectors'.

If your TPS voltage is too high, the ECM automatically is 'thinking' that the throttle plate angle is higher than normal--so additional fuel is added. Check a service manual for the proper specification (typically 0.42-0.68volts throttle plate closed).

Check base ignition timing. It must be at the factory setting.

If you had problems starting your car or truck, check the engine oil--does it smell like fuel ? Check fuel pressure ! Low fuel pressure is sometimes worse than high fuel pressure. If an injector dribbles fuel -- poor atomization is the result. If you're working with a throttle body system, look at the injector spray pattern when running. Use a timing light and note if the pattern changes from a 'mist' to a solid wave at any time. If the pattern also accompanies an engine "misfire"--check the distributor closely. The injector is fired by the ECM via signal from the distributor.

If the calibration doesn't run good "closed loop" let us know what the fuel trim numbers indicate (from a scan tool). Do not phone until engine has at least cycled the cooling fans once or the thermostat has opened--or you've driven at least 30 miles. An ECM or PCM must "learn" new fuel strategies--allow 'learn in' time. Speed density systems are the most difficult to "dial" in, so if all known problems do not seem to be apparent, we may need to recalibrate the fuel curve. Try to include all the camshaft specifications when you fill the order form. Do not build low compression engines with wild camshafts--you won't like the result.

My car starts and runs, idles great, but is rich or lean at cruise...

First off--don't overlook the basics. Plugged fuel filter, air filter, spark plug condition/wrong reach or vacuum leaks.

1. Check the O2 sensor, restricted fuel injectors, low exhaust back pressure (non factory exhaust system) or high exhaust back pressure--(too much EGR)

2. Check the ignition system for misfire, weak ignition or pickup coil, bad DIS coil pack or leaking secondary wires (plug wires). Spray the plug wires with a soapy water solution and listen for an engine idle misfire--you can often visually see the ignition leakage.

3.Test ignition coil output. An engine should be able to run (idle) with a 1/2-3/4" open gap at the ignition coil tower with a spark tester. This is a coil "stress test".

4. Check for vacuum leaks, fuel enriched engine oil, water in fuel, excess methanol in fuel or high "ethanol" blend or oxygenated fuel. Do not run high octane fuels unless instructed to do so. All factory calibrations are designed for 85-93 octane ratings unless engine modifications justify high octane. Volatility rates for high octane fuels can lead to poor cold starts, vapor locking problems and poor driveability in very hot climates. Lower octane in low altitude can lead to detonation problems with high performance calibrations. High octane at high altitudes can also cause driveability problems unassociated with tuning--but can be corrected with tuning. Higher than normal octane fuel can actually cause code 43 (ESC) tests to fail.

Exhaust manifold to cylinder head, or header collector leaks cause an oxygen sensor (in closed loop) to read 'lean' -- which in turn causes the computer to add more fuel.

My car starts and runs, fuel is correct at cruise, but has no power or runs lean at WOT or rich at WOT...

#1 Check fuel pressure and volume. 90% of high performance concerns are fuel pump or filter related. A dirty "in tank" filter sock will restrict even the best fuel pump.

#2 Restricted injectors. (Lean) This problem may or may not show up at highway cruise, but is very noticeable at wide open throttle. Remember the brake specific fuel consumption rules when picking injectors for your application. Cheap injectors are not worth the money. Buy quality injectors, or have them flow tested.

#3 Check throttle plate linkage for binding or incorrect throttle opening. Check TPS voltage (should be above 4.2 volts at WOT). Check for a faulty ESC (electronic spark control) system (no spark advance will result).

#4 Check for "false knock". Any noise generated (whether real or RFI) to the knock sensor or KS circuit will automatically retard ignition timing. We once had a 454 SS truck that could hardly pull itself when towing anything--problem was a loose hitch ball, which sent the same knock frequency down the frame rails--and was picked up by the knock sensor.

#5 Check for an improper spark plug gap or spark plug reach. Wrong plug reach can change the air fuel ratio, slow the flame front in the combustion chamber and cause increased emissions and very low power--and low fuel economy.

#6 Dirty MAF sensor. If any dirt is on the sensing elements of a MAF sensor, the fuel rate is incorrectly calculated. This can harm overall driveability--and definitely hurt performance, as well as cause transmission problems and detonation.

#7 Wrong MAF sensor or failed MAF sensor. The sensor can correctly show idle flow voltages, but cannot correctly show higher operating loads to the computer. Very poor driveability will results, and very high losses in power--and can result in eventual engine damage. Mounting the MAF sensor in a non-OE position (nearer to throttle body) can be affected by reversion pulses from the intake manifold--and result in incorrect metered air values to the computer.

#8 Wrong in tank pump and regulator. For 2005, some suppliers are sending a complete pump and regulator for supercharged applications which are incorrect. If the pump and regulator from a VIN "Z" truck is used, the resulting fuel pressure is 48-54 (335-375Kpa) PSI. Factory fuel pressure for 2005 trucks (other than a VIN Z truck) is 55-62 PSI. Because of this unknown factor, we suggest getting the number right from the fuel pump before installing, along with the fuel pressure regulator number--BEFORE installing it in the tank.

#9 New problem with some centrifugal superchargers is a unique phenomenon where at part throttle, the buildup in pressure barks back through the impeller--and is picked up by the MAF sensor. This causes an instant frequency change in the MAF sensor signal to the PCM--and results in a very rich frequency problem each time this occurs. Wide open throttle is fine, part throttle is very poor and jerky because of this. The only cure we've seen so far is a larger pulley to drop the supercharger boost pressure, or relocating the MAF sensor to the pressure side of the supercharger, just ahead of the throttle body where it is not affected by these overlap air burps.

OBD2 trouble code chart and diagnostic connector location CLICK HERE