S2000 Owner

Met a Honda Mechanic at a Porsche event. We discussed various problems including a problem with the Gas Cap.

I had an engine check light come on twice in the last month. Seemed to be a loose gas cap. Second time it happened I replaced the gas cap. When I had the engine check light on, the idle was fine. But when the engine check finally turned off (after 3 cold starts)(info from Honda guy) I had a rough idle.

OK, as said above, to eliminate the engine check light, you have to go thru 3 COLD start cycles.

Now, when that was curred then engine ran rough at idle, because it had reset the fuel necessary because of the improper pressure in the system.

TO CORRECT ROUGH IDLE, run engine with no accessories on AT IDLE for at least 15 minutes. The computer will then reprogram itself to correct mixtures etc.

Now, gas cap problem, they have found that it's not the gas cap, but rather the neck causes the cap not to be able to be tightened. See you dealer!!

Slows2k

There has been a TSB for a deformed filler neck for quite some time. Mine was replaced almost 2 years ago.

The fuel filler cap has NO effect on fuel pressure.

The "Idle learn" procedure of letting the engine run at idle untill the cooling fans cycle is reccomended any time the PCM is reset.

cdelena

I have also learned to flip (or replace) the gasket on the gas cap to improve sealing.

Have had decent luck in smoothing idle problems by cleaning the throttle body as others have noted.