Engine stumbles at part throttle accel
Jan 16, 2004, 08:40 AM
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Engine stumbles at part throttle accel
Hey guys.
Is that engine stumble a fuel cut? I haven't been able to get the cel checked out yet. But it has happened to me 3 times now in the past 2 weeks. I was willing to believe it was an anomoly (bad fuel) the first 2 times, but now it's starting to bother me.
I am in SoCal, on 91 octane and have an AEM intake and a turbo back exhaust with a high flow cat.
thx...
SC!
Is that engine stumble a fuel cut? I haven't been able to get the cel checked out yet. But it has happened to me 3 times now in the past 2 weeks. I was willing to believe it was an anomoly (bad fuel) the first 2 times, but now it's starting to bother me.
I am in SoCal, on 91 octane and have an AEM intake and a turbo back exhaust with a high flow cat.
thx...
SC!
Jan 16, 2004, 01:56 PM
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maybe you're open air intake is messing around with your MAF and causing the stumbling. I believe most people will recommend you stick with the factory airbox and use a drop in filter.
Jan 16, 2004, 03:59 PM
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Atlvalet, I did think of that when the light came on the first time. but it has come on 2x since and I have reset the ecu each time. And it doesn't seem to come on at full throttle. Seems to come on at part throttle at like 4500-5000 rpms...kinda sounds and feels like I hit the rev limiter....like it's a fuel cut.
The AEM could well be to blame. I'll be pulling it this weekend and replacing with OEM to see.
I did put 4k miles on my car in the past 30 days also. I flew right past the replacement interval for the spark plugs, I think....I'm at 25k miles.
The AEM could well be to blame. I'll be pulling it this weekend and replacing with OEM to see.
I did put 4k miles on my car in the past 30 days also. I flew right past the replacement interval for the spark plugs, I think....I'm at 25k miles.
Jan 16, 2004, 04:21 PM
#7
Sounds like your hard hitting deal is fuel cut. What is your boost running? I know that people that have turbobacks and intakes tend to run as high as 22psi!!! You should get a boost gauge in there to see what is going on. That is what is causing your fuel cut. As far as the CEL. It could be because of the high flow cat. Just a suggestion. What brand is it?
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Jan 16, 2004, 04:33 PM
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Thats true. I really didn't think about the implications of the turbo back/ intake set up. When in VA, and running /9394 octane fuel, it could probably still run well at 22psi. I could well be seeing the limitations to the SoCal Swill 91. It could well explain why I got a cel within 5 minutes of filling up with 90 octane fuel in New Mexico (highest octane available in that damned place)....
I'll go pick up a boost gauge this weekend as well as removing the AEM. I might remove the GHL exhaust for the time being also since I have to get this thing smogged to get CA plates, I think.
I'm hoping it's not the exhaust/cat that is to blame since I really like the exhaust. I am not sure of the cat's brand. It came with the GHL Exhaust I got from Forge Motorsports. It's about half the size of the stock unit...that much I know!
SC
I'll go pick up a boost gauge this weekend as well as removing the AEM. I might remove the GHL exhaust for the time being also since I have to get this thing smogged to get CA plates, I think.
I'm hoping it's not the exhaust/cat that is to blame since I really like the exhaust. I am not sure of the cat's brand. It came with the GHL Exhaust I got from Forge Motorsports. It's about half the size of the stock unit...that much I know!
SC
Jan 16, 2004, 07:05 PM
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Well it doen't sound like fuel-cut to me. The fuel-cut is much more sudden and there's a violent shudder, especially at full throttle.
When my spark plugs took a dump (twice) I had a similar problem like you're describing.
When my spark plugs took a dump (twice) I had a similar problem like you're describing.
Jan 17, 2004, 09:10 AM
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It is a violent shudder....it feels almost exactly the same as when you hit the rev limiter. And that makes sense because the rev limiter in the Evo is merely a fuel cut.
For what it is worth, I put in some 100 octane yesterday to bring the mix up to about 94 octane.....no engine stumble...no cel.
SC~
For what it is worth, I put in some 100 octane yesterday to bring the mix up to about 94 octane.....no engine stumble...no cel.
SC~
Jan 17, 2004, 09:31 AM
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Ralph, i can pull the code for you. Sounds like it might be something with the EGR or vac lines in around the intake manifold.
If the MAF was unplugged you'd get a CEL immediately and the car wouldnt even move.
If the MAF was unplugged you'd get a CEL immediately and the car wouldnt even move.
Jan 18, 2004, 10:47 PM
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Rob. If you can read it, that would rock. I'll check out my schedule for the week...if we could meet up for a few mins, that would be cool.
Iwent through a whole tank of 95 octane 91/100 mix...no cel.
SC~
Iwent through a whole tank of 95 octane 91/100 mix...no cel.
SC~
Jan 18, 2004, 11:07 PM
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Unless you're also running some sort of aftermarket boost controller/mbc, you should not be remotely close to triggering the boost cut. Did you remove and replace your BOV when you installed the intake? If you did, you may have put it in backwards or have it bleeding to atmosphere due to a loose hoseclamp.
shiv
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Last edited by shiv@vishnu; Jan 18, 2004 at 11:27 PM.
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