I could really use some help here. My 2001 S2000 has a random misfire at idle. The first code is always 1399, but after a few hours of driving I'll have codes for a couple cylinders. Cylinder three (p0303) is consistently the first cylinder to code, but the rest follow after more time until I pull 1399, 0300, 0301, 0302, 0303, 0304.

The misfire happens ONLY at idle, and I get a flashing CEL. Reving the car or pulling away from the light instantly makes the CEL go solid again. The car feels and drives just fine during the entire RPM range, however it idles rough.

Recently my Catalytic convert failed and has been rattling, the core came loose. (Running lean during misfire that damaged the cat? The car is also has over 100K miles)

Here is what I've done so far:

-Switch Coil #3 and #2 (cylinder 2 is often the last to code a misfire) - No change, misfire still started in #3 and #2 is often the last to code
- Ultrasonically cleaned all 4 injectors - car felt slightly smoother, but no change in misfire idle issue.
- Cleaned ISV - car felt better, but no change in Misfire issue
- Replaced MAP with brand new OEM unit
- Replaced spark plugs

Lastly, the car had a valve adjustment at the dealer 30K miles ago. I haven't ever mis-shifted or over-reved the car, so I don't expect the issue to be bent valves.

I've read tons of threads on here, most of the suggestions haven't worked or don't seem like my situation.

Anyone have any suggestions on what my next few steps should be, or have had the same issue with a fix?

Thanks so much for the help!

 

Poping from exhaust on idle? Injectors...

Check my thread...

https://www.s2ki.com/forums/index.php?showt...&#entry15846970

 

It would be a good idea to get another valve adjustment. Also to maybe check fuel pressure.

 

valve adjustment? cracked retainers? compression test? leakdown test? do all those to narrow things down !

 

I just got those codes last night too but my car have no problem holding idle. Check your pcv and see if anything is loose around the intake manifold. leaking air can cause rough idle.

 

HAd the same thing happen to me, ran fine once going, but idle was rough.

Got a new set of injectors(used on the boards) and things have been A ok since.

I also did everything you had done minus cleaning the current injectors.

 

What do the plugs look like?

 

I've also replaced the PCV.

I've been thinking the next step is valve adjustment (that way i should also be able to check on cracked retainers as well)

Even though I've had my injectors cleaned, do you think I should just pick up a used set to firmly rule it out, or is the money better spent somewhere else? If you have a set, feel free to PM me.

 

Actually, running RICH. Unburnt fuel reaches the cat and gets ignited there, causing the cat to overheat and potentially melt internally.

Siepel

 

I was having a similar issue. Misfire's at idle only and random flashing cel's. I tried everything! before I got a valve adj. done.

Valve adjustment fixed it completly.