QuestionQUESTION: This all started 4 months ago... The car is hesitating at 2500 RPMs- on flat land or a hill. We have spent a ton of time and money on repairing stuff that doesn't fix the problem. We've replaced the sparks plugs (gapped correctly), fuel filter, coil packs, coil tower, boots, cam sensor, crank sensor, mass airflow sensor, Checked injectors- they are good, we broke down and replaced the fuel pump (and fuel filter again!) along with the fuel pressor regulator. We've tested the map sensor, it's working. When the fuel pump was replaced the tank was dropped- and it was spotless- no grime at all- shockingly. With all of this it still has the problem. This car has 164,000- never gave me any trouble until now. Here's a few kinks to throw in- we did get an aftermarket radio- it uses a highly sophisticated wiring harness to mimic what the factory radio controls in the car. You can go to Wal-Mart and get a $10 harness for the '99 Sunfire, but in 2000 they changed it- it was $100 just for the harness. The car didn't start this up until well after we installed this aftermarket radio- might just be a coincidence, but who knows! Also, about six weeks into this we just parked the car. It was parked for three weeks, I decided I would drive it one day, and what do you know- no problem what-so-ever! It was perfect for a week and a half! Then it started it up again- that was two weeks ago. Someone said it might be the computer ECM, and that I might need to go get mine re-flashed or get a new one. I haven't done this yet- is this even something that's a possibility? It's just puzzling everyone around here from the shadetree fellas to the Pontiac shop... So this is a good one, what have we overlooked- what should we try next... besides driving the thing off a cliff! :)
ANSWER: Hi Amy:
well your all over the board here with trying parts. First off have that radio removed and try that just to elimiante that from the mix.
My though here is a spark problem due to the sputtering . I would have the wiring between the crank sensor and the ignition module checked. You could have an issue there. This engine doesn't have a mass air flow sensor. You could have an ignition module going bad. You said they changed the coil housing assembly? Those were a known issue with these engines. I would alos have all the ground wires checked going to the engine computer. That is where I would start. I don't think this is engine control module issue "computer" it's eithere a bad connection or an input to the computer or a spark issue. Good luck :)
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QUESTION: Hey Todd,
Thanks for such a quick response. We checked the wires to the computer- everything is in great shape. We replaced the ignition module as well, took the car our for a spin and it's still doing the exact same thing. Luckily I can take it back, so I won't be out any money with that. The radio, it's really making no difference, I've got the original factory radio in right now and it's just bad with it as with the aftermarket. One thing that I did notice tonight is that my spark plug on cylinder one is white. They have been replaced, but none the less there is that one that is white. Could I be so lucky that by replacing that spark plug (again) might do the trick? I might just pick one up tomorrow for the heck of it... I will ask you one more thing though, with all that I've told you- would you drive the car or just leave it parked until we finally get it fixed, if it was your car what would you do? Thanks again. :)
AnswerSperak plugs will not fix it unless you have one gapped wrong or one is cracked. Do amke sure you only use the origianl equipment AC Delco plugs though nothing else!!! Did you check the wiring between the crank sensor and the igniton module the 2 wires colors are yellow and purple. make sure they don not have high resisitance in them.
