Help! Question about performance
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Instructor
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Help! Question about performance
I have a ’12 GS that I purchased used. Other than a M2W switch the car is bone stock performance wise.
A couple of weeks ago I had the car dyno’ed and the car put down 370 rwhp and the a/f ratio was in the high 9’s I am surprised being stock the car was running so rich.
Fast forward to last weekend. I was speaking to another vette owner and he mentioned if cheap gas was put in, the computer would dump more fuel to compensate. He said it could be the car is still in that mode and to reset it, unhook the battery for a few minutes.
Help CF!
Is this possible? Has anyone heard of this and will disconnecting the battery make a difference?
I won’t be able to get back to the dyno for a while so I have no way of verifying with certainty.
TIA
A couple of weeks ago I had the car dyno’ed and the car put down 370 rwhp and the a/f ratio was in the high 9’s I am surprised being stock the car was running so rich.
Fast forward to last weekend. I was speaking to another vette owner and he mentioned if cheap gas was put in, the computer would dump more fuel to compensate. He said it could be the car is still in that mode and to reset it, unhook the battery for a few minutes.
Help CF!
Is this possible? Has anyone heard of this and will disconnecting the battery make a difference?
I won’t be able to get back to the dyno for a while so I have no way of verifying with certainty.
TIA
Melting Slicks
Joined: Oct 2010
Posts: 2,220
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From: Sugarhill Ga
the factory tune is PIG RICH that is why the exhaust tips get black. if you pull the battery it will go back to the default setting of RICH. Usually it only takes 1-2 ignition cycles for the computer to reset. also, unless you get the car up to operating temp, the computer will not have time to lean out. short trips will also cause the rich condition.
Melting Slicks
Joined: Dec 2006
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I don't know the exact specs, but if your engine was running overly rich, you'd have a CEL (Check Engine Light) by now. Remember WOT operation always runs rich, so that sounds about right. Do you have excessive soot build-up on the tail pipes? If not, don't worry about it. It's also normal to have some soot there, since cold engine operation requires overly rich A/F mixtures. If you make a lot of short trips between cold/hot/cold cycles, there's going to be more, obviously. Don't worry it about it man; just enjoy it 
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Instructor
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I just wanted to know if this was a true situation since it is much cheaper to disconnect the battery then have it tuned.
Looks like I am gonna spend the bucks to get it tuned properly. I was told there is a few more ponies in there.
Looks like I am gonna spend the bucks to get it tuned properly. I was told there is a few more ponies in there.
Melting Slicks
Joined: Dec 2006
Posts: 2,694
Likes: 106
Keep in mind you'd lose your engine warranty man. Just not worth it without any other modification, but to each his own. And yes, a tune is irreversible in the sense GM would always be able to see your ECU was tampered with. Dealers can't, but to authorize any engine work, GM always asks to download the ECU tune, and they'd find out at that point. Oh, and the stock tune is not 'pig rich'. On the contrary; with today's emissions requirements, all engines have to run on the lean side to pass. Tunes usually ENRICH A/F mixtures for more power, better drivability (less surging), and to run engine cooler (lean mixtures run hotter). So yes, fortunately, the Vette might run richer than other cars, but not rich by any means. My Vette has the tailpipes pretty darn clean after 4K miles. In contrast, an Azera tech DD I just bought are sooty as hell with less than 1K miles... and has direct injection; go figure. Good luck.
Last edited by JCtx; May 16, 2013 at 03:41 PM.
Melting Slicks
Joined: Apr 2007
Posts: 2,168
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From: Pittsburgh PA
Keep in mind you'd lose your engine warranty man. Just not worth it without any other modification, but to each his own. And yes, a tune is irreversible in the sense GM would always be able to see your ECU was tampered with. Dealers can't, but to authorize any engine work, GM always asks to download the ECU tune, and they'd find out at that point. Oh, and the stock tune is not 'pig rich'. On the contrary; with today's emissions requirements, all engines have to run on the lean side to pass. Tunes usually ENRICH A/F mixtures for more power, better drivability (less surging), and to run engine cooler (lean mixtures run hotter). So yes, fortunately, the Vette runs richer than other cars, but not rich by any means. My Vette has the tailpipes pretty darn clean. An Azera tech DD I just bought are sooty as hell, and has direct injection; go figure. Good luck.
The stock tune will be on the safe side of rich while in PE (Power Enrichment, aka WOT). 9.x:1 AFR I don't believe tho, I would guess the dyno has an issue with their wideband or its an old unit that hasn't been replaced or calibrated in a while.
Disconnecting the battery will reset Long Term Fuel Trims (LTFT) and Short Term Fuel Trims (STFT). Fuel trims are calculated using feedback from the front O2 sensors (Narrowbands). They are used to keep the car bouncing around Stoich (14.7:1 AFR) while in Closed Loop. Once you squeeze the throttle enough to enter Power Enrichment the O2 sensors are out of play as the car goes to Open Loop. Pulling the battery will not get you more power.
Last edited by SK360; May 16, 2013 at 03:45 PM.
Thread Starter
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The E38 in the corvette has no logging or flash counter.
The stock tune will be on the safe side of rich while in PE (Power Enrichment, aka WOT). 9.x:1 AFR I don't believe tho, I would guess the dyno has an issue with their wideband or its an old unit that hasn't been replaced or calibrated in a while.
The stock tune will be on the safe side of rich while in PE (Power Enrichment, aka WOT). 9.x:1 AFR I don't believe tho, I would guess the dyno has an issue with their wideband or its an old unit that hasn't been replaced or calibrated in a while.
