What could this be?????
02-23-2009, 10:42 PM
#1
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What could this be????? ok so i just got my car off of the dyno for a speed density tune and my tuner was complaining about the car missing at high rpm's. its a ls6 stroker and has a patrick g speced cam. i took it out tonight and was messin with it and it seemed to happen around 6200 and the cam is speced to pull to 6800 but i cant pull it that far because it starts to miss. it almost sounds like im bouncing the rev limiter. i tested it in 4th gear so my tack shouldnt have been slower. it also has all brand new PRC dual vaulve springs .660 lift so i dont think it would be trying to float the vaulve.
and it only does it when there is a load on it, and what i mean by that is that i can rev it up in nuetral and it doesnt do it.
thanks for the help.
and it only does it when there is a load on it, and what i mean by that is that i can rev it up in nuetral and it doesnt do it.
thanks for the help.
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02-25-2009, 02:15 PM
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Does sound like it's lacking fuel. You can hook a guage up to your fuel rail and see if it drops when it cuts out. Should be about 40 I believe. Maybe time for a 255lph pump and injectors.
03-05-2009, 01:26 PM
#16
It didn't do it on the dyno, but does on the street with load? What'd the dyno graph look like in the higher RPM's? What spec on the cam?
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03-05-2009, 06:28 PM
#17
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hey matt i tried to call yall today but yall were at lunch...... anyways, yea it does it on the dyno too with a load on it. the cam is a 246/253, .622/.621 112+4 LSA, i dont know what the dyno graph was doin cause as soon as it started doin what its doin i got out of it, the cam was speced to be shifted at 6800 rpms
Thanks,
Austin Rich
Thanks,
Austin Rich
03-06-2009, 08:30 AM
#19
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it's gotta be one of three things, hook a vacuum guage up to the intake and go drive it while it's messing up if you see vaccuum drop off big time, you have valve float, it sounds like a fuel problem, but if he has checked fuel, this is the next likely option, let us know what happens
03-06-2009, 08:32 AM
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If it only does it under load I would check ignition, rev limiter, plug gap, wires. When it was on the dyno did they see any miss firing with the tuning software? With valve float I didn't think your engine missed I thought it just stopped making power.
If it was a fuel problem I would think the AFR would change during the dyno run giving you clues.
If it was a fuel problem I would think the AFR would change during the dyno run giving you clues.
Last edited by mike13; 03-06-2009 at 08:37 AM.