jdmb16crx

The BreakDown of the car. 2000 Honda S2000 BONE STOCK 90k miles.

Alright, i figured i'd try and pick a few of you expiernced s2k owners brains. My car developed a slight MIS about a week ago. nothing major, just slight MIS at idle, wouldnt hesitate or break up under a load. Yesterday the car started running like complete garbage, almost like there was a dead cylinder. Performed a compression test, Cylinder 1: 220psi, Cylinder 2: 222psi, Cylinder 3: 215psi, Cylinder 4: 225psi. I did all the basic's, Made sure all 4 coil packs were sparking, Switch Plugs, Unplugged injectors.

The car has a Horrible MIS at idle now, and under a load at low RPM's at wide open throttle is where you really feel it. Anything over 4k and up is smooth and still pulls top end and has power.

I'm running out of Idea's and out of patience, Today was the first time it actually threw a CEL, and i had All misfire codes, Cyl 1, Cyl 3 Cyl.4, Random Misfire and Multiple misfire. The only thing that i'm pondering but don't want to is possibly a bent/chipped valve? But wouldnt my compression number's be off? Any help/tips would be greatly appreciated, i read the whole add that GENT had posted in the common problems sticky thread, just didnt see anything that really pin-pointed my issue.

Thanks,
-Ryan S.

03_BB_S2K

Try and perform a "map whack". It might be your map sensor causing the problem. Perform a search on how it's properly done and hopefully the symptoms will go away

H22toF20

The plugs OK? All of the injectors working?

twohoos

I had the exact same symptoms as you! Just an intermittent misfire at idle, plus it tended to miss when under load at around 3000rpm, but was fine at 4K and above. Happened whether the engine was cold or hot. Tried all the fuel system cleaners, no luck. Then, all of a sudden, it completely went to $h1t with a constant misfire and MIL.

Towed it to a shop; they checked plugs, coil packs, etc. -- all good. They found that the OBDII reported misfire on cyl#3 regardless of where they swapped plugs or coils, and all wires checked out, so we replaced the ECM.

Result: Well, it's 98% better.

The original symptoms are still there; not as bad, but definitely there. Seems to do better just after an ECM reset. Not throwing any codes (pending or otherwise), so the shop says "come back when it gets bad again."

My working theory: some electrical gremlin is causing the ECM to try to compensate, which leads to misfires as the ECM learns, and ultimately causes the ECM to burn itself out. (The tech said the ECM was sending *too much* current to the misfiring coil, and that the top of the coil pack was turning bright blue and was hot to the touch! Coil still worked, but they replaced it just in case.)

Right now I'm doing three things:
1) Injectors: Just to be sure, bought some low-mileage used ones cheap; plan to make sure they're good and clean. (Also installed new spark plugs, again just to eliminate them as a source.)
2) Coil packs. There have been 4 different coil pack part numbers for our car!
2000-2003 P/N: 30520-PCX-007 (still available, about $90 ea. online)
2004-2005 P/N: 30520-PNA-007 (superceded, now generally unavailable - you'll get the ones below if you order them)
2004-2005 P/N: 30520-RRA-007 (replacement for PNA-007; this coil pack is shared with the Acura RSX and available for about $45 ea.)
2006-2009 P/N: 30520-PZX-007 (available online for about $67 ea.)
I don't know what the difference is, but coil pack failures are known to happen, and some of the forced-induction guys swear by the RSX parts.
3) Underhood wiring: Cleaning and checking chassis-ground connections to ensure no parasitic loads are tricking the ECM.

Let us know what you find out and I'll do the same.

jdmb16crx

Yea..unfortuneatly i think im going to have to face the facts. Im going to do a leak down test tomorroe at work..im leaning towards a valve issue in the cylinder head..so looks like im pulling the head and ordering ap2 valves, springs and retainers...

s2klariat

Have you changed the fuel filter recently?

jdmb16crx

No, i havent replaced the fuel filter since i've owned the car. I did do an induction service on the car last night, and the car ran better for a while, but then went back to MIS and threw every mis-fire code in the book other then cylinder 1.

s2k16803

Sounds to me like you have a vacuum leak or sumthing is wrong with the map sensor.... I have a synapse engineering missing link under my map sensor and it went bad one day aka vacuum leak right were the map sensor is. It would barely idle but if I took it on the highway it would drive perfectly fine.

jdmb16crx

*update*

now throwing CEL for Cylinder 2 , Cylinder 3, Cylinder4 misfire, Random Misfire and Multiple random misfire.

I bought some stuff front advance auto parts to clean the valves, instead of dumping in the gas tank, i pulled it through a vacume source on the intake manifold so that it could get to all the valves. After i did that the car ran the smoothest it ever has, No MIS at idle, QUIET as hell..Drove it, still had a little MIS under a load at lower RPM's but it cleared up immidately. Turned the car off and let it sit while i cut the grass and then the MIS was back.

turbo_slug

have you ever peeked into your injector ports? when i had misfire problems, everything was fixed when i replaced the injectors + cleaned the injector ports. the injector ports were full of gunked up carbon (looked like wet espresso grounds).

i wonder what are the chances that your cleaner somehow washed away enough crap from your intake manifold that the car ran better for a short while. anyway, try cleaning the fuel injector ports to see if that helps. if you don't want to replace the injectors, try soaking them in kerrosene over night?

btw, since it sounds like you have an obd2 scanner, what's your long term fuel trim number?