1997 chrysler 3.5 l lhs

QuestionEdit

Hi Roland, A friends car caught on fire in the right hand corner of the engine compartment. We have managed to fix all of the wiring harness and replace it. We replaced the crank sensor, Iac sensor, map sensor, checked all the rest of the sensors, checked all vaccuum and repaired all vaccuum leaks, replaced coil, checked all harnesses for ohms n voltages all fall within spec. All connectors are in good repair. Checked fuel pressure and pump, they were all good. Checked timing belts to see if there was any damage or if it was out of time and it was fine. I am a mechanic and I have had 4 other techs work on it as well and we have over 40 hours into this car, and we are still having the same problems as was occuring prior to being repaired. The car starts and runs perfectly until it warms up approx 5 mins and then it starts to sputter and run rough and then quits. It will immediately fire up and repeat that process 30 seconds into the second starting.The codes are 11, 12, 22,23,54,55. We replaced the crank sensor with a new one it was faulty due to the fire. all other parts were replaced with used parts that were checked and appear to be good and in better repair than the originals on the car. The parts we replaced were fine but were changed out due to the heat factor from the fire.Have you any ideas on what could be the problem so I know where to go from here. (other than the scrap yard lol) the ecu seems to be functioning fine its bringing up codes it is the corner where the fire was. I have gone back through the harness and sensors 3 times and can not find any reason as to why it will not run once it warms up. I appreciate any and all help you can give me. Thank you Kim

AnswerEdit

Hi Kim, My first question would be whether all the codes are 'fresh', and whether there might be any that have been repaired and are stale. You can cancel the codes by disconnecting the battery for a few moments. Then start and run the engine and see whether they all come back. If all are still present then I would suggest verifying the sensor ground connections from the intake air, engine coolant, cam and crank sensors (all black/light blue wires) to pin 27 at the pcm. The temp sensors are simply resistive elements but you could verify the signal wires for those to the pcm, and the cam and crank sensors share the need for an 8 volt supply on the orange wire and their signal connections could be checked as well. Let me know if you don't have the pin assignments at the pcm or wire colors for the signal wires. Does the ect sensor resistance drop to around 1,000 ohms after the engine warms/5 minutes? There may be air in the cooling system/thermostat housing which is causing a false cold reading on the ect which leads to a too rich mixture. Have you bled the cooling system via the bleeder valve at the front of the engine while adding coolant to the in-board side of the bottle? Put a 4' hose on the bleeder to collect coolant in a pail in front of the bumper until it runs out free of air, and keep recirculating it back into the bottle until it does so. The coolant bottle should be empty on the outboard side (pinch the return hose on the bottom of the bottle to keep it from filling up while you are doing the bleeding). I would suspect the cam sensor (54 code) if the ect is OK, particularly if the that code is 'fresh'. The only other part that can make for rough idle and which is not well 'sensed' by the on-board diagnostics is the egr valve. If it hangs up ajar that can lean out the mixture like you describe but usually it does it from the cold start situation and doesn't come on after a warm-up period. But if nothing else is suspect you might want to clean that valve out. Those are my thoughts at this point. Please "rate" my answer (see below). Thanks, Roland