Hesitation And Stalling

[Orbitz]

Hi all. I’ve been having problems lately with the Bonnie. Car has the regular 3800, no mods, and I run it on regular gas. Since I bought it, it would hesitate slightly when going up very large hills. I didn’t pay much attention to it, as it didn’t happen too often. A few months ago, she started missing badly. It turned out to be the ignition control module causing the heavy missing, but even after I replaced the module (I had to use a used junk yard module), the heavy missing has gone away, but the car is stating to stall when it feels like it. Usually, I am traveling slowly (20 KPH or less), but it has also done it at around 60 KPH. It just dies when it wants too. Power is fine, heater and everything works fine, but the engine just dies. At other times, I have watched the tach drop to zero, and actually heard the engine almost shut off (just as if someone quickly turned the key to Off, then back to On), but sometimes it doesn’t die. It doesn’t seem to matter what speed I am traveling, where I am traveling (inclines, declines, etc.), or even temperature. Usually, if I put it into Neutral, it will fire back up, and drive fine, but twice it has quit, and taken several minutes to re-start (starter just keeps cranking, but engine doesn’t start). I have replaced the plugs and wires (with Delco’s), changed the fuel filter, and am always “good” to the car. I can also hear the fuel pump coming on, and there are no check engine lights. My local parts man suggested the crankshaft position sensor (or the camshaft position sensor, I can’t recall which). Would either of these cause these symptoms? Could it be the ignition control module is bad again, seeing how it is a junk yard part? We really need the car to get back and forth from work, and the stalling is getting worse (happened 3 times today, on two different trips). Any suggestions? Thanks everyone.

[Archon]

The tach dropping out is a good indicator of an intermittent crankshaft position sensor. It would be possible that the ICM is a problem, as the signal passes through it. With that already swapped out, the crankshaft sensor would be a good bet.

[Orbitz]

Thanks Archon, I appreciate it. I have a question before replacing the sensor. Would this sensor cause any kind of check engine light, or any code an OBD II reader would pick up? It isn't reading any codes, and I'm just not sure if I should go with replacing the ICM (the one in now is used, from a junk yard), or the sensor.

[Archon]

A fair amount of time the crank sensor will be defective and never throw a code.

[Orbitz]

Gotcha. Well, I will have the sensor replaced, and post back with an update. Thanks again for your help, it is much appreciated.

[Archon]

Good luck. Hope that it takes care of your problem.

[Orbitz]

I read on another site that after installing the crankshaft position sensor, a 'relearn' procedure must be done. Do you have any idea if this is true, and if it is, what it requires? Also if I don't do it, what conditions will it cause?
Thanks again

[Archon]

It is recommended that the CKP System Variation Learn, or CASE learn be performed after the sensor is replaced for optimum engine performance. It is not required for the engine to run, and there may be times that it will still be within specs, even after replacement. A DTC will be set if it is too far out of spec. A Tech II, or other scan tool capable of performing the task, is required. This is what is required.

The crankshaft position system variation compensating values are stored in the PCM non-volatile memory after a learn procedure has been performed. If the actual crankshaft position system variation is not within the crankshaft position system variation compensating values stored in the PCM, DTC P0300 may set, refer to Diagnostic Aids for DTC P0300 Engine Misfire Detected .

The Crankshaft Position System Variation Learn Procedure should be performed if any of the following conditions are true:

DTC P1336 is set
The PCM has been replaced
The engine has been replaced
The crankshaft has been replaced
The crankshaft harmonic balancer has been replaced
The crankshaft position sensor has been replaced

IMPORTANT:

Set the vehicle parking brake and block the drive wheels when performing the Crankshaft Position System Variation Learning Procedure in order to prevent personal injury. Release the throttle when the engine reaches the SECOND fuel cut off. Leaving the throttle open during the fuel cut off will allow the engine to decel at an even rate. Once the learn procedure is completed, the PCM will return the engine control to the operator and the engine will respond to the throttle position.
The scan tool crankshaft position system variation learn function will be inhibited if engine coolant temperature is less than 70°C (158°F) . Allow the engine to warm to at least 70°C (158°F) before attempting the crankshaft position system variation learn procedure.

The scan tool crankshaft position system variation learn function will be inhibited if any powertrain DTCs other than DTC P1336 are set before or during the Crankshaft Position System Variation Learn Procedure. Diagnose and repair any DTCs if set. Refer to Diagnostic Trouble Code (DTC) List/Type .

The crankshaft position system variation learn function will be inhibited if the PCM detects a malfunction involving the camshaft position signal circuit, the 3X reference circuit, or the 18X reference circuit.

If the scan tool indicates a problem with the cam signal, refer to DTC P0341 Camshaft Position (CMP) Sensor Performance .
If the scan tool indicates a problem with the 3X crank signal, refer to DTC P1374 Crankshaft Position (CKP) High to Low Resolution Frequency Correlation .
If the scan tool indicates a problem with the 18X crank signal, refer to DTC P0336 Crankshaft Position (CKP) Sensor Circuit .

Set the parking brake.
Block the driver wheels.
Ensure that the hood is closed.
Start the engine and allow engine coolant temperature to reach at least 70°C (158°F) .
Turn OFF the ignition.
Select and enable the Crankshaft Position Variation Learn Procedure with the scan tool.
Start the vehicle.
Apply and hold the service brake pedal firmly.
Ensure that the transaxle is in Park.
Increase accelerator pedal position until CKP system variation learn fuel cutoff is reached. CKP system variation learn fuel cutoff is reached at 5150 RPM . Release the accelerator pedal when the second fuel cutoff is reached.
The crankshaft position system variation compensating values are learned when RPM decreases back to idle. If the procedure terminates, refer to Important above for instructions.
Observe DTC status for DTC P1336.
If the scan tool indicates that DTC P1336 ran and passed, the Crankshaft Position System Variation Learn Procedure is complete. If the scan tool indicates DTC P1336 failed or did not run, check for other DTCs. If no DTCs other than P1336 are set, repeat the Crankshaft Position System Variation Learn Procedure as necessary.

[Orbitz]

Much appreciated Archon. I'll have it installed, and see how it goes, but in the meantime, I'll try to find someone with a compatible scanner.
You have been so much help, and I really appreciate it. I'll post back after the sensor is replaced (should be this weekend). Thanks again!!

[Orbitz]

Had a mechanic look at the car today. I was going to replace the CPS, but he noticed the water pump was leaking. He suggested the pump is leaking down onto the CPS, and causing it to short out, and the car to stall. What do you guys think? I know the pump needs to be replaced (now that I know it's leaking), should I just replace the sensor too?

[Archon]

The CPS and its connector are pretty well sealed against the elements. However, there have been cases where metal shavings have become attached to the sensor, interfering with its operation. You could try replacing just the water pump, and then using compressed air, blow it around the sensor and see if helps. I suppose it's possible that the extra stickiness of the coolant could cause things to collect on the sensor.

[Orbitz]

Gotcha. Well, I just remembered that auto parts (at least, around here) stores don't usually take back electrical items, so now that I have it, I think I'm just going to have it, and the water pump replaced and see how she goes from there. I hate these *dang* intermitent problems. If something's wrong, I'd rather she just tell me, and I'll fix it!
Thanks again Archon, I'll post back when repairs are done.

[Orbitz]

Sorry for the delay. Mechanic was busy until yesterday. Had the sensor replaced. Car seems to not be running the same (I can't quite pin point it yet though), but doesn't seem to be stalling out anymore *touches wood*.

Thanks again for the help, it is really appreciated!!