Engine Stumble Above 1800RPM

[rperry435]

Seems like this is a problem for a few people so I figured id start my own thread because Ill have it figured out here in a day or two at the most.

First started of as a miss/stumble just as I pulled out of my driveway in the morning. As it has persistently gotten worse I've been able to pin point the problem is only when the RPM reaches above 1800rpm and giving it some throne (intermittently you'll see it cut out ).

I managed to get a video of it today while driving since my wideband will clearly show when the problem occurs (gauge reads super lean, above the 17mark and into --)

I have no codes and has this problem has been eluding me for a few weeks now but I'm leaning towards the ICM at the moment, next obvious choice is CKP Sensor which is a little more work to change.

I've got an extra set of coils I could try but the problem is only above 1800rpm with 25-30% throttle, still idles perfect with no misses and has its normal amount of power. The problem never occurs below 1800 with any amount of throttle. and since these two things can be bad without throwing a code they'll be my first to change out.

Ill upload a video in a minute

[rperry435]

https://www.youtube.com/watch?v=fej-...e_gdata_player

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[BillBoost37]

Shotgun the coils would be my first try from experience. Maybe the ICM.

[rperry435]

Yeah I'm going to swap coils first for ****s n giggles. but I really find it hard to believe it's them since it idles and runs fine under hard acceleration. It's only when give it some gas just above 1800rpm while in lockup so the engine load is increasing steadily. We shall see.


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[BillBoost37]

I found it hard to believe that a 1000 rpm spike was coils myself. However after diagnosing it and talking with a bunch of trans guys etc on why it seemed that the trans was slipping oddly like that, I built one and tossed it in. Problem got worse which led me to shotgunning parts on hand since nothing was showing on the scanner etc.

Found it... 1/4 coil pack. When that got swapped by itself, all was right in the world.

[rperry435]

It's funny you say 1/4 coil because my aeroforce has occasionally shown a heavy misfire on cylinder 4 at random times for no reason., other times it's perfect no misses. Even after new plugs and wires. I'm gunna try the extra set of coils I've got after work.

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[BillBoost37]

Mine never showed me a damn thing

[rperry435]

Well that was it. My 1/4 coil was the issue. Hasn't acted up since I changed it and I did a highway run no hiccups :beer:

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[rperry435]

Nope Nvm not it. Ive got a few codes this time. Looks like an issue with my main ignition 1 relay.

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[BillBoost37]

Hmmm keep us up to speed. Maybe you had multiple issues.

[rperry435]

Feels exactly the same. I got a p0204 (which is #4 injector fault thought that was the issue) and P0131 (o2 circuit sensor voltage low.

Scanned it at work again this morning with the tech2 also had a p0202 which is injector #2...
Figured it was odd issues with both out of nowhere.. Checked the bcm and bam found a b1428 code. I'm almost positive this is the problem, ignition 1 relay is dropping out and Injectors get power from that relay so I'm going to start there.

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[rperry435]

Still working on this issue. Not sure if this second problem is Connected but

Also have no gauges, service stability, abs, low fuel, and my aeroforce doesn't communicate just flashes the annuncator like when ignition is off when it acts up.

Car runs and drives normal even while it's doing this peticular symptom while when the other issue is a blank out as if no fuel on my wideband.. This issue has been a fun one to track down. I'm starting to think it's the pcm.

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[rperry435]

will a bad o2 cause this hesitation problem im experiencing? i mean i see the wideband show a serious lean condition when it does it. i just wondered if its bad and im chasing a ghost.

[rperry435]

It's weird no symptoms for a month or two and its back. Thought I solved it with changing the coil. But I'm starting to think ICM for the split second "cutting" out and bad PCM for the gauges (except speedo) going dead and DIC showing low fuel, service abs and stability. Damn electrical gremlins.

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