Uh-oh..wifey calls...rough running and CEL...

[billb]

rough running while at a stoplight, then momentary CEL at around 35mph a little bit later... I just did an "italian tuneup" last night for about 30 minutes, then went and filled up with 91 Exxon. Drove spiritedly home from that.

Wonder what I cooked up/burned out? Recently replaced valve cover gaskets, and there was no oil leakage into spark plug wells. May have fouled the O2 sensor...last replaced in 2001, at 79k miles...seems too soon for that though.

This is the worst possible timing for problems with her car. Like there's ever a good time. I'll see what the stomp test gives me.

[Mr Project]

Coil(s)?

[billb]

Coil(s)?

Let's hope it's something simple.

[Jon K]

Let's hope it's something simple.

Coils are simple, but not cheap.

[billb]

Coils are simple, but not cheap.

Checking out the cheap/simple stuff first. Oddly enough, when it's running rough, disconnecting the MAF connector causes it to run smoothly again. Might I be on to something there?

[ryan roopnarine]

ummmmm.......
1222 is o2 sensor but that doesn't mean anything. any massive vacuum leak or vacuum hose kink will throw that code (ask me how i know...) if you disconnect the maf while it is running, it should run like crap.

[billb]

still throwing 1222 code, but I did not find a leak anywhere. I checked every hose in the idle circuit, FPR, crankcase ventilation, etc. All good, no leaks anywhere that I can find. At first, it was just sporadically hesitating, then idling up high to recover, then repeating. It steadily got worse this evening as I was testing it out. Eventually, it did that enough that the CEL came on steady and it went into default mode, taking everything out of the loop, and runs smooth...but with lit CEL.

In efforts to level the playing field, I reinstalled the factory chip (removed the EAT). No change.

Suspiciously enough, I just filled up last night...wonder if bad gas/water in gas could cause all this mess?

New O2 sensor is $69.00...and it has been 45k miles since last one...that's way too short a life.

Suggestions, comments, snide remarks?

[billb]

I just can't see a large-scale vacuum leak on this thing (or even small scale!) It seems to do it once the engine's up to temperature, so it's when it goes closed-loop. It almost behaves like a shot O2 sensor, but I'm getting 1222. Of course, the last time this happened, I got 1221, not 1222.

Any thoughts of problem-prone areas? Gotta get this thing back up and running for the missus.

Thanks.

[ryan roopnarine]

if the cel is on constantly, but you have a normalized idle, it could be that the computer just adjusted to the problem and will try to substitute an idle speed conducive to it running somewhat properly. i'd unplug the battery and see what it does sans memory and see what problem is being covered up.

ps. i only say this because i know it from experience. if the ICV hose is kinked, the car will adapt a high idle (but steady and seemingly normal) of about 800-900-1000 rpm after about 30 mins or so of runtime. it could have adapted to whatever problem you have.

[billb]

ECT sensor checks okay. There was oil in the sensor cavity, maybe shorting out the connector. Removed, replaced with known clean good one from my E30 (same part number), and cleaned connector. No better.
Replaced FPR vacuum hose-old one looked okay, but as a matter of course...
All, and I repeat, all vacuum hoses look good, including fittings.
Valve cover gasket was recently replaced 500 miles ago, and is still sealing well.
Oil cap secure, fuel cap secure.
Charcoal canister lines look good.
Replaced o-ring on crankcase ventilation fitting at valve cover, good snug fit now.

Disconnected battery, clearing codes (1444), then repeated the earlier starting exercise. It starts smartly, runs for a few minutes, then the idle gradually becomes more unstable, until, after about 15-30 seconds, it oscillates wildly, from low 100's up to 1500 or so, about 2-3 times, then dies, running rich when it dies.

This one's got me stumped. Oh, and it hasn't thrown a code again yet...