Funny noise when shifting under hard acceleration... Backfire????
Thread Starter
Burning Brakes
Joined: Nov 2001
Posts: 812
Likes: 1
From: Sherman Texas
Funny noise when shifting under hard acceleration... Backfire????
My 92 (auto) makes a loud "thud", kinda"pop" noise when it shifts under hard acceleration.. Sounds like it could be exhaust backfire, but the engine runs great, no noticable loss of perfomance when this occurs... It is worse when the ASR is on.. Any Ideas??? Its is driving me nuts :crazy: .. I have done some work on the rear end, which did not change this problem, worse or better.. I installed poly bushings, outer tie rod ends, and new wheel bearings. Thanks in advance for any help... :cheers: :flag
Safety Car
Joined: May 2003
Posts: 4,283
Likes: 0
From: Houston Texas
Re: Funny noise when shifting under hard acceleration... Backfire???? (thmupr)
Other forum members with 92's have complained of this. If you do a search you can find post. Or somebody that has had that problem will chime in.
Le Mans Master
Joined: Oct 2000
Posts: 6,362
Likes: 30
From: Oak Harbor WA
Re: Funny noise when shifting under hard acceleration... Backfire???? (BAM92)
Uh, a TSB is out there about this on the 92's I think. I just don't remember off hand what it was. Could be ECM needs updated code?? :confused:
Else it could be the Opti going south. Mine does it too under heavy acceleration. :banghead:
Else it could be the Opti going south. Mine does it too under heavy acceleration. :banghead:
Pro
Joined: Apr 2002
Posts: 629
Likes: 0
From: Rutland Ma
Re: Funny noise when shifting under hard acceleration... Backfire???? (thmupr)
Yes i have the same problem. Gm has a "Technical Service Bulletin" for the 92 year corvette concerning this. I still haven't had the problem fixed so i can't hlp you much more. I didn't really realize that its was a backfire until i pulled the mufflers off and heard it pop.
Burning Brakes
Joined: Oct 2001
Posts: 1,135
Likes: 17
Re: Funny noise when shifting under hard acceleration... Backfire???? (thmupr)
My 92 (auto) makes a loud "thud", kinda"pop" noise when it shifts under hard acceleration.. Sounds like it could be exhaust backfire, but the engine runs great, no noticable loss of perfomance when this occurs... It is worse when the ASR is on.. Any Ideas??? Its is driving me nuts :crazy: .. I have done some work on the rear end, which did not change this problem, worse or better.. I installed poly bushings, outer tie rod ends, and new wheel bearings. Thanks in advance for any help... :cheers: :flag
:cheers:
Daniel
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Re: Funny noise when shifting under hard acceleration... Backfire???? (thmupr)
My 92 has the same sort of condition, but I just attributed it to the fuel cut-off at 5800RPM and that seems to be just where the 1-2 shift occurs on mine. While I haven't notice this condition getting worse, it is there.
Have you tried to adjust the TV cable to see if that may be a solution? If somebody can post the TSB, it would be a big help!
UPDATE :D
Just checked the Alldata website where I found some info: http://www.alldata.com/TSB/10/92100604.html Scroll down the page where you begin to see dates in 1992. In Dec 92, there was a TSB issued for "Backfire during WOT 1-2 Upshift" The TSB is number 923366E and the listing shows the problem appears to be PROM related. The ALLDATA website only provides titles and TSB numbers and dates so you either have to buy a subscription or get the data from another source.
If you go to http://www.alldata.com and select the Technical Service Bulletins tab, you can specify year, make and model to see a listing of TSB's. Going to the Corvette page, there is a separate page for ZR-1's.
HTH :D :cheers:
[Modified by c4cruiser, 4:34 PM 9/24/2003]
Have you tried to adjust the TV cable to see if that may be a solution? If somebody can post the TSB, it would be a big help!
UPDATE :D
Just checked the Alldata website where I found some info: http://www.alldata.com/TSB/10/92100604.html Scroll down the page where you begin to see dates in 1992. In Dec 92, there was a TSB issued for "Backfire during WOT 1-2 Upshift" The TSB is number 923366E and the listing shows the problem appears to be PROM related. The ALLDATA website only provides titles and TSB numbers and dates so you either have to buy a subscription or get the data from another source.
If you go to http://www.alldata.com and select the Technical Service Bulletins tab, you can specify year, make and model to see a listing of TSB's. Going to the Corvette page, there is a separate page for ZR-1's.
HTH :D :cheers:
[Modified by c4cruiser, 4:34 PM 9/24/2003]
Thread Starter
Burning Brakes
Joined: Nov 2001
Posts: 812
Likes: 1
From: Sherman Texas
Re: Funny noise when shifting under hard acceleration... Backfire???? (thmupr)
Thanks for the input guys! :cheers: It is indeed a TSB.. and it states that the prom is in need of replacement. The TSB does not say much other than that. I'll let ya know if it fixes it!! :flag :chevy
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Thread Starter
Burning Brakes
Joined: Nov 2001
Posts: 812
Likes: 1
From: Sherman Texas
Re: Funny noise when shifting under hard acceleration... Backfire???? (oldace84)
The only code I have had in a while was code 32.. Here is a little background on the engine--- Opti, plugs, wires, and TPS replaced within the last 8 months. New Delco OPTI unit.. Doesn't use oil, 90+ Octane all the time,,, Borla Mufflers, and the "Tri-Claw" SLP intake.. Runs great other than that noise.. I did order the new prom for it that GM thinks will fix this problem.. Only $48 shipped from GM Parts Direct.... :cheers: :flag
