92 Running Rich?
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Instructor
Joined: May 2002
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From: hastings mn
92 Running Rich?
Hi, I asked this question a bit last season, but thought I would ask again. I just took my vette out of storage yesterday, and in general it is running pretty good.. It still backfires occasionally when I decelerate and leave the clutch out. It is embarrassing more than anything. What I have noticed also is that the inside exhaust outlets on my corsa exhaust are black and full of soot, Only the inside outlets, not the outside.. Thought this was a bit strange. I also have an intake gasket leak, (oil) do you think this may be a cause for the back firing? I replaced spark plugs last year, but not the wires. I plan on replacing the wires and the intake gasket here shortly.. Could a new coil help? Maybe the spark isn't powerful enough to burn all the fuel, and that is why I get a backfire..
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Joined: Feb 2003
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From: Lake Wylie SC
Re: 92 Running Rich? (gbfan10)
Hi,
Take out a spark plug (an easy one) and have a look. If it appears to have carbon deposits, dry sooty deposits, this might indicate a rich mixture or a weak ignition. This could cause misfiring, hard starting and hesitation. You say you have a 92 (just like mine) hows the opti-spark look? I took mine out and found the inside wet, dirty and full of rust. Before I took it out, it ran okay, but not up to par. After some research here on the forum and in my service manual and the Chevy Dealer guys, I found our Opti-Spark distributors have a design flaw. It needs to be vented as in the 95-96 Lt-1s. You might look here in your investigation. As far as running rich, that could be in the ECM management of your injectors, or a problem with your injectors. I've also seen problems with the EGR system causing the engine to run rough or even stall. That's my input. I'm sure others have more to work with. :yesnod:
Strick :flag :flag :flag
Take out a spark plug (an easy one) and have a look. If it appears to have carbon deposits, dry sooty deposits, this might indicate a rich mixture or a weak ignition. This could cause misfiring, hard starting and hesitation. You say you have a 92 (just like mine) hows the opti-spark look? I took mine out and found the inside wet, dirty and full of rust. Before I took it out, it ran okay, but not up to par. After some research here on the forum and in my service manual and the Chevy Dealer guys, I found our Opti-Spark distributors have a design flaw. It needs to be vented as in the 95-96 Lt-1s. You might look here in your investigation. As far as running rich, that could be in the ECM management of your injectors, or a problem with your injectors. I've also seen problems with the EGR system causing the engine to run rough or even stall. That's my input. I'm sure others have more to work with. :yesnod:
Strick :flag :flag :flag
Le Mans Master
Joined: Jun 1999
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From: Chino Valley AZ
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Currently Corvette-less
Re: 92 Running Rich? (gbfan10)
gbfan,
Here's my $.02 worth.........
I suspect that your backfiring is from a combination of two (or three) things.
1. Have you changed your o2 sensors since the car was new? If not ~ this could be causing the over-rich problem.
2. Injectors ~ Mine were trashed after 80K miles. If the pintals are worn out ~ they might be flowing too much fuel. Mine were.
3. Fuel pressure regulator. Is yours stock? Have you checked the fuel rail pressure? If it is too high ~ too rich.
4. Intake manifold leak. Usually just an oily mess, but it could be a vacuum leam leak and messing up the fuel/air mixture. (Not the highest probability).
5. Bad plugs or plug wires.
6. OptiSpark.
~ Purp :flag
Here's my $.02 worth.........
I suspect that your backfiring is from a combination of two (or three) things.
1. Have you changed your o2 sensors since the car was new? If not ~ this could be causing the over-rich problem.
2. Injectors ~ Mine were trashed after 80K miles. If the pintals are worn out ~ they might be flowing too much fuel. Mine were.
3. Fuel pressure regulator. Is yours stock? Have you checked the fuel rail pressure? If it is too high ~ too rich.
4. Intake manifold leak. Usually just an oily mess, but it could be a vacuum leam leak and messing up the fuel/air mixture. (Not the highest probability).
5. Bad plugs or plug wires.
6. OptiSpark.
~ Purp :flag
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Instructor
Joined: May 2002
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From: hastings mn
Re: 92 Running Rich? (PurpleC4)
Thanks for the quick responses, I forgot to mention I did replace the FPR last season and I replaced all the injectors with the cobra SVTs.. I have about the same result before and after...
I have never replaced the O2 sensors, I may look into doing that asap now!
(I bought the car last year with 84,000 on it...)
I have never replaced the O2 sensors, I may look into doing that asap now!
(I bought the car last year with 84,000 on it...)
Le Mans Master
Joined: Jun 1999
Posts: 6,272
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From: Chino Valley AZ
Cruise-In I Veteran
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Currently Corvette-less
Re: 92 Running Rich? (gbfan10)
Cobra SVT's? Are you referring to the FMS 24#/hr. injectors? I hope you didn't go any larger. If you did, that would not be good.
Also, if you replaced the fuel pressure regualtor ~ what pressure are you now running?
~ Purp :confused:
Also, if you replaced the fuel pressure regualtor ~ what pressure are you now running?
~ Purp :confused:
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Joined: Jan 2002
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From: ny
Re: 92 Running Rich? (PurpleC4)
Make sure you don't have an exhaust leak before the O2 sensor.It will fool the sensor thinking that it is running lean.I found this out the hard way after changing lots of parts for no reason.I had a hair line crack in the weld where the primary tubes meet the collector.I couldn't hear or see the leak but it was there.
