I have a 2003 Cobra and yesterday I went to start the car up for the first time in about 2 weeks and it seemed to hesitate a little when it fired up. Once it started running the idle was very rough almost as if the car had camms. No engine light on. Check the oil it looks clean, no leaks anywhere. Has anyone had this happen or have a clue of what it might be?
2003 Cobra Rough Idle Check Engine light is not on???
- Thread starter Gambler213
- Start date
to many things can cause this..gas,moisture on coils,ect
I did have something like this on ours..
parked car,it was fine..
started the next morning and it .would not idle..had to hold gas till engine warmed..
no engine light..problem was cyl 6 dropped a valve seat..
we had ours since 03..many miles and this has been our only issue on idle problem..
we did have to replace coils at 200k.
caused a miss,never a code but these didn' affect idle or starting.
I did have something like this on ours..
parked car,it was fine..
started the next morning and it .would not idle..had to hold gas till engine warmed..
no engine light..problem was cyl 6 dropped a valve seat..
we had ours since 03..many miles and this has been our only issue on idle problem..
we did have to replace coils at 200k.
caused a miss,never a code but these didn' affect idle or starting.
Did you let it run up to normal temperature ? If so did it smooth out ?
What was the ambient temperature when you started it ?
Lots of information needed , to be able to answer your question
What was the ambient temperature when you started it ?
Lots of information needed , to be able to answer your question
It was about 50 degrees I let the car run for a little bit to see if it would smooth out but it didn't. I also didn't let it warm up because I was afraid of causing damage to the car. While it was running it seemed to have a lot of gray smoke coming from the exhaust. I know there can be a lot of things causing this, just freaking out it's a major issue
Frps is my guess
So nothing unusual happened around the last time you drove your Cobra?
just another thought..
intercooler..leak/crack..will make car run like crap..lots of smoke..
will happen at anytime.
there are 4 orings ..these are common..
intercooler..leak/crack..will make car run like crap..lots of smoke..
will happen at anytime.
there are 4 orings ..these are common..
All those were replaced about 4 months ago due to a leak which caused the car to not run at all, intercooler was fine no cracks.
who did the work?
if it' smoking now..it can still be from them..or more..
being the only 1 who works on mine,
I be doing a compression test for starters..
leak down test would be better but to me I would do that after a bad basic test..
I had to learn the hard way on this car..I've had a few head scratchin issues,,come to find a basic compression test is what pointed to the issue each time..
and was used to confirm overheating issue was not from engine..
on your issue..
what modifications have been done..
other repairs recently..
A local performance shop done all the work and the car ran great until yesterday. The mods on the car are 2.93 pulley, Accufab throttle body, Afoc heat exchanger, borla exhaust and CAI
Sounded like the computer was re-learning itself.
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Check, or replace the plugs. I just went through something similar.
I 2nd pulling the plugs and give them a good going over. Boosted cars are hard on plugs. I always keep a spare set for reasons like this.
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Turns out it was a bad EGR. Problem solved and runs like a dream
Good info my car had a intermittent rough idle from day I picked it up. Ford never did figure it out but voided my warranty said I ran octane booster caused it. Although I had them mark down problem before accepting delivery. Anyway I will put one on. Thanks always good info here. FYI SVT team engine engineer got my warranty reinstated 
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