Car/engine shaking at cold idle
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OrangeMustangGt
Founding Member
yeah damn mine has been doing that soo much recently. mine surges when cold, till teh comp kicks in, i think its cause of i have a bad upper/lower intake gasket, causing a lean condition. ill see tommorow.
mo_dingo
20+ Year Stangneter 
Rough idle could be caused by many things. But lets start here. Does the car only idle poorly when the car is cold? What happens once the engine is warm?
Just to get it out of the way, your O2 sensors are definately not the problem in this case.
I would start with cleaning your MAF/IAT sensor. If you haven't done it recently, then you should try it. It's free anyway! next remove your spark plugs, and inspect. They should be dirt brown, with no white or black marks.
Also, you might want to think about a plugs/cap/wires/rotor/fuel filter tune-up if it hasn't been done.
Something that could specifically be wrong would be your FPR. It responds to engine vacuum to lower the fuel pressure. If it's not working, then you would be running rich. (at idle, the vacuum will literally suck the fuel out of the injectors, so that is why the pressure regulator lowers the pressure at idle).
Don't assume it's anything specific yet. Just do the simple & free stuff for now & post back.
Scott
Just to get it out of the way, your O2 sensors are definately not the problem in this case.
I would start with cleaning your MAF/IAT sensor. If you haven't done it recently, then you should try it. It's free anyway! next remove your spark plugs, and inspect. They should be dirt brown, with no white or black marks.
Also, you might want to think about a plugs/cap/wires/rotor/fuel filter tune-up if it hasn't been done.
Something that could specifically be wrong would be your FPR. It responds to engine vacuum to lower the fuel pressure. If it's not working, then you would be running rich. (at idle, the vacuum will literally suck the fuel out of the injectors, so that is why the pressure regulator lowers the pressure at idle).
Don't assume it's anything specific yet. Just do the simple & free stuff for now & post back.
Scott
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