View Poll Results: What's my problem?
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Breaking up top RPMs, but not losing power, thoughts?
09-26-2009, 10:24 AM
#1
Breaking up top RPMs, but not losing power, thoughts? The last 2 times I've been to the track I've experienced this, but last night it really made me wonder.
Quick synopsis: T56 swap, 27" BFG DR's, 3.23 rear, intake, catback, tune, 159k mile original LT1. Every time I race, I'm getting more and more MPH out of the car, but going though the traps (3rd gear at redline - 6k) I can hear the motor breaking up. It starts breaking up at about 5300 or so, up to redline. I'm trapping over 106 MPH now, so its making power up top, so this confuses me.
First impression - possibly ignition, but no other symptoms to verify this, and the ignition system is relatively new in its entirety.
Second thought - valve float? It is a 160k mile engine that I've always run hard.....
Could also be fuel, but I had the injectors cleaned about a year ago. Pump?
Help me get started in the right direction!
Quick synopsis: T56 swap, 27" BFG DR's, 3.23 rear, intake, catback, tune, 159k mile original LT1. Every time I race, I'm getting more and more MPH out of the car, but going though the traps (3rd gear at redline - 6k) I can hear the motor breaking up. It starts breaking up at about 5300 or so, up to redline. I'm trapping over 106 MPH now, so its making power up top, so this confuses me.
First impression - possibly ignition, but no other symptoms to verify this, and the ignition system is relatively new in its entirety.
Second thought - valve float? It is a 160k mile engine that I've always run hard.....
Could also be fuel, but I had the injectors cleaned about a year ago. Pump?
Help me get started in the right direction!
Last edited by 94Z28rag; 09-26-2009 at 05:12 PM.
09-27-2009, 05:26 AM
#2
everytime I've had an ignition issue up top it's not just a light missfiring, its like hitting a wall. Been through bad plug wires a bad opti and a cracked plug, all were very noticeable. I hit valve float at about 5600 when dynoing my new engine combo, again power fell off real quick and didn't sound good either. No other symptoms like hard starting, stumbling, etc?
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10-03-2009, 11:43 PM
#9
Like does it make crackling noises at those RPMS? If so I had similar issues. Popped in a new opti (original had 158k on it) and it cleared it up. If you can find a way to test your opti to make sure before you pull everything apart, go for it.
10-04-2009, 04:43 AM
#10
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I had the exact same problem and it took me over a month to figure it out. Mine was my plug gap being set to big. Reset my gap and it quite. Also check you wires might be arcing with the higher voltage at higher rpm
10-04-2009, 08:15 AM
#11
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i had a similar problem, it started out as a miss every once in a while around 6k then it progressed to what felt like a rev limiter at about 5500. it took about 6 months to get to that point and i have fought it for that long trying to figure it out. i changed opti, plugs, wires, and coil. i blew both head gaskets in the process. turned out to be an auto zone icm, wich was fairly new. put the oem on and it hasn't missed a beat
Last edited by crypt; 10-04-2009 at 08:21 AM.
