Exhaust popping question
Thread Starter
TECH Regular
Joined: Apr 2015
Posts: 423
Likes: 2
From: Rochester, NY
Exhaust popping question The engine stock, with cats & y-pipes stock also - running into a GMMG chambered exhaust. Manual transmission, it runs & sounds great.
Since the exhaust system was installed, I'll get a pop when shifting gears. It usually happens when I'm driving moderate or more aggressive, it'll do the pop when I shift into the next gear. Nothing when lightly driven.
I'm not sure if back pressure is an issue with the y-pipes being stock diameter, or unburnt fuel. I can understand if it was the different sizes in the pipes. If its fuel, why is it now, with the new exhaust, I'm getting these pops when shifting gears?
Any ideas?
Since the exhaust system was installed, I'll get a pop when shifting gears. It usually happens when I'm driving moderate or more aggressive, it'll do the pop when I shift into the next gear. Nothing when lightly driven.
I'm not sure if back pressure is an issue with the y-pipes being stock diameter, or unburnt fuel. I can understand if it was the different sizes in the pipes. If its fuel, why is it now, with the new exhaust, I'm getting these pops when shifting gears?
Any ideas?
TECH Apprentice
Joined: Jan 2004
Posts: 392
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I'm the same as you with a stock engine, headers, y-pipe, and still have my cats. I have the GMMG and it does the occasional pop. Usually when I shift from 2nd to 3rd during normal driving. I've gotten used to it. I have driven with the GMMG since about 2004 and have not had any issues other than the occasional popping.
TECH Fanatic
Joined: Sep 2005
Posts: 1,584
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From: NYC
They all pop a little after being tuned. It can be eliminated by adjusting the DFCO, but you will burn a lot more fuel: http://www.hptuners.com/help/vcm_edi...uel_cutoff.htm
Thread Starter
TECH Regular
Joined: Apr 2015
Posts: 423
Likes: 2
From: Rochester, NY
I too like the "gurgles and cracks" but not so much the pops.
And Yes, it seems to be mostly the 2nd to 3rd shift!
I'll look into the DFCO more this weekend, thanks for the tips!
And Yes, it seems to be mostly the 2nd to 3rd shift!
I'll look into the DFCO more this weekend, thanks for the tips!
Thread Starter
TECH Regular
Joined: Apr 2015
Posts: 423
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From: Rochester, NY
The popping during shifts only happens before the car is fully warmed up.
I dont drive very far to work, so I dont always get the car up to temp before i'm there. On a longer drive, I found the popping doesnt happen.
So if the car is popping in Open loop, that would be all MAF related, instead of o2 sensors? I'm thinking a good MAD cleaning should help.
I dont drive very far to work, so I dont always get the car up to temp before i'm there. On a longer drive, I found the popping doesnt happen.
So if the car is popping in Open loop, that would be all MAF related, instead of o2 sensors? I'm thinking a good MAD cleaning should help.
Last edited by michaelhawk; Nov 18, 2016 at 11:35 AM.
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If you have a maf, log the maf signal between shifts and see what it does. If you see some kind of spike then thats your answer, the maf tube needs adjustment. Try the OEM air filter tract to see if that will fix the issue.
Otherwise, there are other reasons why an engine can pop or seem to back fire when shifting. One of them is a leaky injector. Another is TPS noise causing AE enrichment when there is no need for it. You might inspect the plugs for signs that one is darker than the rest, and you might also try driving the car gently with the TPS unplugged. You could also try unplugging the O2 sensor(s).
Otherwise, there are other reasons why an engine can pop or seem to back fire when shifting. One of them is a leaky injector. Another is TPS noise causing AE enrichment when there is no need for it. You might inspect the plugs for signs that one is darker than the rest, and you might also try driving the car gently with the TPS unplugged. You could also try unplugging the O2 sensor(s).
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TECH Regular
Joined: Apr 2015
Posts: 423
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From: Rochester, NY
Good tips KingTA!
But, in my case - cleaning the MAF did the trick.
Cold, Warm ort Het, Open or closed loop, hard, light or medium shifts the popping is basically gone.
Only a slight noise (i wouldn't call it a pop anymore) when shifting hard, but I'm tossing that up to normal.
But, in my case - cleaning the MAF did the trick.
Cold, Warm ort Het, Open or closed loop, hard, light or medium shifts the popping is basically gone.
Only a slight noise (i wouldn't call it a pop anymore) when shifting hard, but I'm tossing that up to normal.