Mechanics

2.4L, 111,000M STALLS WHILE DRIVING

2000 Pontiac Grand Am

Vehicle started stumbling when started, ran rough, 40 mph top speed, cat converter glowing orange. Error code: Random multiple misfire. Replaced coil housing, coils, and boots. Vehicle ran fine except it started shutting off while driving. Error codes: Faulty crankshaft position sensor, Cat converter. Replaced crankshaft position sensor.

Vehicle still shuts off randomly while driving. I can run full rpm shifts with no problem. Just randomly shuts off and most often will resume before vehicle totally shuts off and has to be restarted. No error codes. Problem came on literally overnight.

New coils had primary reistance of .5 ohms each, secondary resistance was 9,100 and 9,300 ohms (books calls for "roughly" 4,000 to 8,000). Had Crankshaft position sensor variance learn procedure run by dealership. Still shuts off. Sensor reads 751 ohms and produces .002 AC volts (yes, that is correct) while cranking. Bad sensor? Tested voltage later and come up with 1.5 - .5 AC volts, not sure why. Spliced in new connector to Ignition Control Module, still same problem.

I posted this a couple of months ago, but....

Update 10-17-07

Believe this or not, with a conversation with a Tech from Wells Manufacturing (maker of all the parts I purchased), I was convinced to change the spark plugs - Autolight Double Platinums with only 9,000 miles on them (rated for 100,000 miles). Believe this or not, seems like problem solved. I would never have believed it other than to humor him before spending more money. But seems like all is OK! Will update tomorrow if time permits.

Update 4-21-08
Problem still persists, 4 sets of platinum plugs fouled, Autolite and Bosch. Still shutting off, running rough till plugs are changed. Replace Cat converter and O2 sensor, found downflow O2 sensor looked hideous (sagging cage from converter overheating). Runs good now but mileage down. Vehicle shuts off and no longer restarts. Sprayed starting fluid into intake, fired right up. Replaced the fuel pump, runs a whole lot smoother. No longer shutting off, 2 weeks now. I think the failing fuel pump was the problem from the start, starving the engine, computer over compensating, etc, etc.

Interesting article, defect investigation on the fuel pumps at www.recalls.gov
http://www-odi.nhtsa.dot.gov/defects/defectsearch.cfm
Avatar
Prankster
August 30, 2007.



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