Took my 2001 GT (auto trans) out from storage just to drive for couple days and it was sputtering.
Engine starts fine and idles and revs perfect when in park or neutral however when placing in gear the rpms drop (gets worst as the engine is warmer) and hesitates between 400-500 rpm..then on acceleration it sputters pretty bad. So far I replaced the battery, EGR valve vacuum control solenoid, throttle position sensor. I ordered a maf sensor and fuel filter and will be replacing those Monday, also cleaned my K&N filter. Anything else that would cause this issue?? Plugs, wires, coils?? Even if it revs perfect with no load?? Thanks for any help..

 

Is your car showing any DTC codes? You should not have spark wires on your car. Check the COP, and fuel filter. Narrow down the problems and don't just buy new parts.

 

swapped out maf today from my friends 01 gt and still same symptoms, no DTC/engine codes, I will be replacing fuel filter tomorrow. Any method for checking the coils before replacing? Is there any vacuum lines that go to the transmission that I could check?

 

Might want to check the iac?

 

its your cop you said it idles fine so rules out the iac so 100% yeah its one of or serval coils gone bad more than likely its gonna be just one may wanna find some coils on ebay for it at dealers and places like autozone itll cost u well over 300 dollars vs on ebay more like 100 dollars and some change

heres a way to test the coils

 

I agree. It can idle fine, but under load it can begin to misfire. My money is on coils.

BTW you don't need a check engine light to check codes. I didn't have one on, but ran a scan anyway and found 2 codes.

Good luck.

 

I checked the cop (while engine is running) by disconnecting and reconnecting each harness one at a time,.. each time the engines tone/rpm decreased (assuming that each cop is good, cause if it didn't make a difference on a certain cop would mean its bad)...

Is this method accurate??

Is there a way to test cop under load??

Btw no codes, using scanner and sct tuned...

Thank you..

 

Yeah, they can all be good at idle, so maybe that method won't tell you if one or more went bad. I'm not sure about how to test under load. Too bad no codes though. I wish I had better info for you man. Sorry.

 

Definitely sounds like cop.was it a very damp or rainy day? I had a F150 and would act up on rainy days and usually good on others. I experienced a bad cop throwing code for particular cyl miss fire and other times when they did not throw codes but were bad. you can get new generic on ebay for $13. they worked for me.

 

Took the car out couple days ago and drove it around for a few minutes and finally got a CEL code P0308 cylinder 8 misfire detected. Turns out to be a bad spark plug, coil was still good. Problem solved...