Eismann

Hey guys,

I have a 2005 that when I start the car it shudders for about 5 seconds when RPMs go low then levels off at about 650-700 RPMs. It also does it when I put it back into park. Could this be happening due to needing to clean or possibly replace fuel injectors or could my fuel/air mix be off just a little bit? I know it is getting enough spark since I put on a Screaming Demon coil pack with 8mm wires and new plugs gapped at .64 about a year and a half ago.

Thanks for the info.

Nuke

Clean the throttle body first. That is a likely culprit.

Also, the aftermarket COPs are known for issues. If the TB cleaning doesn't fix it, try re-installing the stock COPs.

jimkaray

No COP's on the 4.0 but your logic still applies, aftermarket coil packs seem to fail frequenly as do the aftermarket COP's. I would suspect throttle body or IAC valve though based on it acting up at idle.

MustangFirstCar

Clean the TB and change your idle to about 900 if you have a tuner

Eismann

Thanks guys. I will make sure to clean the tb this weekend when I have the car torn apart already.

Nuke

Yeah, I should have thought that one out. My wife has the 4.0....