Revved to 6600?

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Apr 4, 2025 | 11:04 AM

Gav

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From: UK

Revved to 6600?

Just crapped myself, have stock cos3 pcm with cutoffs for fuel at 6300? I think it would have carried on going….any ideas?

Apr 4, 2025 | 11:15 AM

G Atsma

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From: Central Cal.

Did it rev that high in gear, or did it free rev going out of gear?

Apr 4, 2025 | 11:40 AM

Gav

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From: UK

Pretty sure it revved that high.....
it's 90mm Holley cable throttle body but shouldn't matter?
I'm ls1 turbo so some people don't like fuel cuts anyway? But it didn't happen.....
as a failsafe just dropped timing to 12 across board at 64000 ish, how low could I go?
regards
gav

Apr 5, 2025 | 12:38 AM

gametech

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From: Stockbridge GA

The factory PCMs don't seem to react quickly enough to keep up with the rate of rpm change with a turbo motor. I have mine set for a 7000rpm limit, and have seen 7300 on the scanner before it cut off in first and second gear. That is with an Hptuners 2bar COS on a p59 pcm.

Apr 5, 2025 | 11:14 AM

grubinski

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From: Carnation, WA

Quote:

Originally Posted by gametech

The factory PCMs don't seem to react quickly enough to keep up with the rate of rpm change with a turbo motor.

Interesting … I saw ~7600 once with my limiter set at 7200, and was not happy, given my SBE. No turbo here, but a healthy NA motor in a 2400 lb car probably gains revs just as quickly.

Apr 5, 2025 | 02:36 PM

gametech

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From: Stockbridge GA

Quote:

Originally Posted by grubinski

Interesting … I saw ~7600 once with my limiter set at 7200, and was not happy, given my SBE. No turbo here, but a healthy NA motor in a 2400 lb car probably gains revs just as quickly.

Fuel cut rev limiters really suck at fast response. Unfortunately, that is what the factory computers are stuck with for emissions reasons. There are custom OS options to get around this if you don't have to worry about your pcm playing nice with a bcm, but not everyone has that option.

Apr 10, 2025 | 01:28 AM

LS_caddy

Staging Lane

Joined: Nov 2019

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I think someone modified a 12587603 image to work with boost and use dwell for spark cut. Most of the modifications are done in empty flash areas. It should still work with the BCM.

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Apr 10, 2025 | 01:10 PM

gametech

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From: Stockbridge GA

Quote:

Originally Posted by LS_caddy

I think someone modified a 12587603 image to work with boost and use dwell for spark cut. Most of the modifications are done in empty flash areas. It should still work with the BCM.

It depends entirely on which platform you are running. On my GTO I would lose at least 2 BCM functions if I switched from the correct 7604 OS to the BoostOS modified 7603. Username Phoenix, who compiled a 7604 xdf with an e85 flex patch tried the 7603 on his gto, so I tend to believe him about which incompatibilities he found.