What does it mean....
Thread Starter
Instructor
Joined: Jul 2011
Posts: 166
Likes: 0
From: Chardon Ohio
What does it mean....
When a car backfires during shift? I just installed Bosch III injectors on my 92' Vette that has long tubes, x-pipe, and flowmasters and since then almost every 1-2 shift(automatic) it backfires loud enough to compare to 2 or 3 firecrackers set off at the same time.. its LOUD. But this only happens under WOT, not regular driving. The car does have a shift kit of some sort from the previous owner not sure if its "electrical" or mechanical but the shifts are very firm. Before the injectors were put in the car would only do it about 1 out of 8 times under hard acceleration and now it's just about every time.
Navigator
Joined: Aug 2011
Posts: 9
Likes: 0
From: Fort Myers Florida
Similar problem
I installed a Hypertech chip and thermostat a few years back on my 92 conv. and it does the same thing at max rpm. Acts like the computer is killing cylinders or it's running out of fuel. WOT is the only time I have an issue and this bug has been bugging me for a long time. I'm thinking about trying a new fuel filter. A guy at Mid America suggested I might need a fuel pressure regulator. If you solve your problem let me know because the fix may be the same for mine.
Thread Starter
Instructor
Joined: Jul 2011
Posts: 166
Likes: 0
From: Chardon Ohio
Starduster- I already installed a new filter and still does the same.
BADDUCK- It did this with the old injectors. And actually before the new injectors my SES light would come on showing a rich reading on the left o2 sensor. But hasn't come on at all since the new injectors have been in.
BADDUCK- It did this with the old injectors. And actually before the new injectors my SES light would come on showing a rich reading on the left o2 sensor. But hasn't come on at all since the new injectors have been in.
Thread Starter
Instructor
Joined: Jul 2011
Posts: 166
Likes: 0
From: Chardon Ohio
I installed a Hypertech chip and thermostat a few years back on my 92 conv. and it does the same thing at max rpm. Acts like the computer is killing cylinders or it's running out of fuel. WOT is the only time I have an issue and this bug has been bugging me for a long time. I'm thinking about trying a new fuel filter. A guy at Mid America suggested I might need a fuel pressure regulator. If you solve your problem let me know because the fix may be the same for mine.
Navigator
Joined: Aug 2011
Posts: 9
Likes: 0
From: Fort Myers Florida
Re: What does it mean
Rgr that, I should mention that I haven't tried the fuel pressure regulator that the guy at Mid America suggested so he and BADDUCK may be right. They're probably starving for fuel. I relocated the MAT Sensor but that didn't help either. I've called Hypertech and they want me to pull the chip and get the numbers off of it but I haven't done it yet, maybe I will this fall or winter when it's cooler (SW FL).
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Q - What causes a "backfire"?
A - Extra fuel in the exhaust system that is ignited.
Problems that can occur include shattering the cats and ruining the mufflers.
How does that extra fuel get in there at WOT?
A - Extra fuel in the exhaust system that is ignited.
Problems that can occur include shattering the cats and ruining the mufflers.
How does that extra fuel get in there at WOT?
Burning Brakes
Joined: Nov 2008
Posts: 995
Likes: 1
From: Naples Campania
It happens to me too. Not constantly, but under certain situations. Less with shifting and more if I'm WOT in 3rd, someone cuts me off, and I decel still in 3rd (auto). Nice loud bang.
I'm catless, so that might be part of it. Fortunately, since I don't have a cat I get a little bit of fire at night
The good thing is this won't really cause damage to your motor itself. It runs rich for a moment then the fuel detonates in the exhaust. A slightly rich mixture in the motor actually protects it, just DON'T GO LEAN!!!
The worst I've seen happen was it actually blew a guy's gasket out between his long-tubes and the y-pipe. That was a GTO approaching 1K HP, so I don't think this will happen to you.
Worst case senario? There is so much fuel and it's the perfect mixture in your exhaust when it hits your cat (which are VERY VERY hot) and it turns your exhaust into a pipebomb. Maybe a valve?
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