'04 XC Engine Misfiring-Further Updated (Moisture ruled out - possible defective coils, bad MAF) Topic is solved

Post by **abscate** » 17 Jun 2020, 15:45

I think they usually do. My PEM failure did not

Post by **E Showell** » 17 Jun 2020, 19:05

Idle smoothes out the second I turn off the CEL.

Post by **abscate** » 17 Jun 2020, 19:08

That’s with a reset of codes with Vida?

Is it idling ok with the MAF disconnected?

Post by **E Showell** » 18 Jun 2020, 03:10

Yes. VIDA "clear all" gives me an instantly smooth idle.

MAF. Is brand new. Haven't unplugged the new MAF.

Post by **E Showell** » 18 Jun 2020, 07:46

I'm finding VIDA worse than useless in these circumstances. It really isn't telling me anything.

And it is not at all apparent that you can get a fuel pressure reading out of it. Principal utility seems to be running the battery down.

Post by **jimmy57** » 19 Jun 2020, 15:37

OK. Whenever the idle speed is not controllable the ECM does random cylinder canceling to keep speed lower (prevents startling driver and runaway car allegations when throttle is punched instead of brake...). Lumpy idle and sometimes misfire codes from this FMEM. The air leak code is the ECM saying it can't drive throttle low enough to control idle speed satisfactorily. Look for air leak, hose, etc. Also need to inspect throttle to assure it is not gunked up or possibly something stuck in it. The throttle checks aren't easy but I get a feeling the idle overspeed control is your lumpy idle that goes away with a code clearing.

Post by **E Showell** » 19 Jun 2020, 15:55

Throttle body replaced with used unit cleaned to hospital clean room conditions. FMEM?

Idle overspeed control?

Post by **jonesg** » 20 Jun 2020, 04:18

E Showell wrote: 19 Jun 2020, 15:55

Idle overspeed control?

A form of limp mode.
If signal from sensor on the foot pedal doesn't match the throttle body its a safety issue.

Post by **E Showell** » 22 Jun 2020, 11:04

Utterly defeated here. Alas, I have discover I am at best a paint-by-numbers-wrench, a/k/a mechanic wannabe. I'll do fine if I already know what the problem is, but, as a diagnostician, my wrenching skills leave much to be desired. Off to the local independent shortly.

Post by **abscate** » 23 Jun 2020, 03:18

That’s a tough one. Don’t beat yourself up,you’ve got the logic brain m having seen first hand.

I’m guessing an intake air leak, brake booster, manifold, purge line, pcv, snorkel crack? Have you had the snorkel off?