fishthis10

I have a rough idle and just assumed it was time to replace coils. It is an 04 S with 84k miles. I bought new coils and plugs. I was surprised to see that none of the coils (part ends in 03) were cracked, but I replaced them anyways and changed the plugs. I notice that I have a lot more power now, but still have a slight rough idle. It is slight, rpm drops a couple hundred RPMs. Also seems to do it as I am coming to a stop. Seems to get better when I put it in neutral. Any other ideas of what else I can look at?

deilenberger

Replacing parts is an expensive way to troubleshoot IMHO. You might consider hooking it up to a diagnostics machine (dealer or a Durametric) and seeing if any codes are stored. Since you have 84k miles - has the throttle-body ever been cleaned? When gunked up (and they ALL do eventually) it can cause a rough idle. As can intake leaks or dirty injectors.

I would R&R the intake throttle body and clean both sides and the bore, replace the seal to the intake runners, and then run some Techron through the fuel system.

vyper340

There is also the possibility of the cam position sensors or the crank position sensor

deilenberger

Shouldn't those trigger a check-engine light?

fishthis10

I had the crank shaft position sensor replaced about three months ago, but I have had the idle problem even before this. I was also thinking it could be throttle body. I will try cleaning the throttle body.

gbratk

Do you solve the problem? I Have the same problem, for a few days now.

I change plugs and coils two month ago, I also change the crankshaft position sensor.
But strange is that this is happening only when I run on GAS when I run on LPG the problem is gone.

There is also no fallout codes.

ekstroemtj

Good Morning
I can tell you i got a new throttle body because of some codes which didnt
Want to go away. The car is running fine again, but the situation
With the idle at cold start or at stops is still there.
So... MAF changed. Throttle changed. Must be some other reason

Basal Skull

The timing chain I'm these engines stretch, particularly with long oil change intervals/higher mileage and need to be adjusted/replaced

D-Rob

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