Thread: Serious part throttle kr and stalling.

Small update. I've come to realize that more then anything when I first start the car up it runs really rough and misfires basically until the o2 sensor takes over?

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Originally Posted by mguzzo

Unplug your MAF , see if it still runs rough at cold start

There didn't seem to be much of a difference at all

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Latest update. I drove to work and back. It drives completely fine in normal driving but for the first minute its started and is cold it will run rough and misfire a bunch. And it will be fine up until about 70% throttle and that is when it will start cutting out but doesn't show any misfires and wide band doesn't look like it goes lean.

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Could this be a bad crank position sensor? I got a cel for a valve position sensor about a month ago but I deleted it and it never came back

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Well vacuum is reading normal and if it was a vacuum leak wouldn't it not effect higher rpm or at least as much? I'm expecting the pump myself although I'm considering the icm as well I have autolite 104s too and haven't changed them in about 10k so maybe they are just getting blown out or something.

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Well after doing some more research and watching videos my problem at least when going WOT really sounds and looks like spark blow out. The engine stuttering and then the popping out of the exhaust. Now that I'm actually thinking about it that popping is probably unburnt fuel which would lead to an ignition problem rather then a fuel problem.

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I was also wondering if on e85/e54 if you should run a smaller gap. Right now my plugs are gapped at .53

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Well I've had too work a bunch the past few days which has made finding time to work on the car very difficult but I replaced the rear plugs last night all of which looked in good shape with no weird deposits or cracks. Went for a drive and no change. I also replaced my icm and all three coil packs with no change uhh. Plug wires look okay but are a couple years old. Looks like ill be replacing the fronts tonight and ill be able to dig into it more tomorow when I finally have a day off.

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I gapped the rears at .46
Update: so I've been watching my aeroforce and its showing misfires in multiple different cylinders although cylinder 2 is the most common. But apparently its not missing enough to set a cel or even a pending code. Whatever this problem is, it also seems to get worse when its hotter out for some reason. So its misfiring at idle, and wot but perfectly normal when cruising. I've also been driving it daily for the past three days and have not had another stall or no start condition so I'm starting to think that was just some crazy hoax

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As of yesterday plugs are new. Plug wires are 2 years old although visually look good. O swapped the icm and all 3 coil packs with spares already and it didn't change anything. Basically wires are the only ignition item I haven't changed unless its a fried wire or bad pcm or something

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Ok I have a theory!!! The past few days I've noticed my interior lights being dimmer then they normally were but my voltage was always reading around 14 when I was driving around. But tonight I monitored it more carefully and come to realize the misfires are a lot worse when I have the a/c on and when I was actually stopped not driving my voltage was dropping to high 11 low 12. It was crazy I did a little wot pull with my interior light on and they became at least twice as bright when I gassed it compared to when I was sitting still. So my theory is either my battery or alternator is bad which when the car is under heavy load is causing the misfires because the ignition system doesnt have enough power!! Woo bamm wamm!

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I took out my zzp voltage booster. (Stage 1) and when I was normally cruising around I was seeing low 13 volts and at idle it was the same 11.9 to 12.1. I broke my multimeter but the aeoroforce also says with the engine off the battery is 11.9v

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Also noticed in a scan I took that every time I went wot the tps sensor was saying approximately 85% not 100%

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Originally Posted by GTPpower

I would pull the alternator off and get it tested.

Do you know if O'Reilly or autozone does that? I know they test the batterys but Idk about alternstors?

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