balakris

I have a bone-stock AP2. On start-up in the mornings recently, I get a very rough idle almost to the point of stalling the first few seconds, then the idle evens out again. It has been doing this only recently. Any suggestions as to what the problem might be? Fuel filter needs to be changed? I have about 41k miles.


Thanks,

Arun

Wisconsin S2k

The fuel filter is not a serviceable item on this car, and it is unlikely that is the "problem".

to be honest, I dont really think you necessarily have a "problem" yet. To start, do NOT give the car gas after you start it, no matter how much it seems like it's going to stall. Your ECU may just be confused and/or need to adjust to the weather changes you've been having. This is the most common reason this happens.

Give it a couple days, and I'm willing to be it will go back to normal on its own.

daytontp

What is the RPM you notice the rough idle? On my 2005, I notice it is rough at 1100-1200rpms for the first second or so of start up. I think this is inharent with the balancing and high compression of the engine. I noticed once when the engine was warm, I pressed the gas a little to raise the revs to this mark and it felt the same as it did at cold startup, well maybe not as bad. But, it does feel a little rough.

I think you are noticing 2 different things now that I think about it more. The S2000 motor has a very high compression ratio compared to most road cars, and due to this it takes more energy in combustion and the starter motor to turn the engine over. This is the very abrupt thing you feel initially when you press the start button. The other is the slight roughness at the rpm listed above, which is to a degree repeatable if you press the gas to hold that rpm.

Hope this helps.

balakris

I don't rev the engine. I let the ECU adjust which it does in time. I have a feeling it does have to to with the weather as you suggested. I'll give it more time and update soon.

balakris

[QUOTE=daytontp,Mar 17 2006, 07:42 AM] What is the RPM you notice the rough idle?

Wisconsin S2k

yeah give it a few days and a few more starts. if it doesn't go away, try the "map sensor whack" which instructions are located in the FAQ at the top of this forum

Eluded

what is the outside temperature?