Engine started backfiring...
Thread Starter
Drifting
Joined: Oct 2001
Posts: 1,699
Likes: 1
From: Westampton NJ
Engine started backfiring...
I have just received a *wonderful* present from my Corvette...a backfire problem.
I've dealt with carb backfires before due to my stabbing the distributor wrong, but this is driving me nuts.
My car, with no changes for the past several weeks has developed an exhaust backfire. It's on the passenger side bank and only one cylinder. I'm going out to double check the timing now, but I'm worried about it.
How likely is it that I've wiped a cam lobe? What are the other possible causes?
I've dealt with carb backfires before due to my stabbing the distributor wrong, but this is driving me nuts.
My car, with no changes for the past several weeks has developed an exhaust backfire. It's on the passenger side bank and only one cylinder. I'm going out to double check the timing now, but I'm worried about it.
How likely is it that I've wiped a cam lobe? What are the other possible causes?
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
Re: Engine started backfiring... (Cali,68,L-79)
When does it backfire? If it does it when you let up on the gas, ie, the engine is braking the car, I would suspect an exhaust leak. Check the entire exhaust system from manifold to muffler, leaky gasket or a hole or break anywhere can cause a backfire. MJ
Drifting
Joined: Feb 2002
Posts: 1,906
Likes: 0
From: Berlin
Re: Engine started backfiring... (rainman69)
Mine has started backfiring through the exhaust too. It usually does it only when the engine is cold (under 160 degrees) and when increasing throttle. I guess its a carb problem?
Thread Starter
Drifting
Joined: Oct 2001
Posts: 1,699
Likes: 1
From: Westampton NJ
Re: Engine started backfiring... (rainman69)
It backfires at idle and part throttle. Not an engine braking issue. I forgot to mention that.
It happens two ways:
1) pop ... pop ... POW!!
2) POW!!! unexpectedly sometimes.
It happens two ways:
1) pop ... pop ... POW!!
2) POW!!! unexpectedly sometimes.
Intermediate
Joined: Sep 2003
Posts: 38
Likes: 0
From: Arlington Tx
Re: Engine started backfiring... (rainman69)
My experience with engine backfire is that the cylinder is firing while
the exhaust valve is still open, rather than being shut as it should. I've seen
a slipped or loose timing chain as a possible problem. CDC
the exhaust valve is still open, rather than being shut as it should. I've seen
a slipped or loose timing chain as a possible problem. CDC
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Re: Engine started backfiring... (rainman69)
:rolleyes: I developed a misfire once from damaging the plug wire boots. I used a sharp toothed Leslie tool to remove the boots for a plug change. Started miss-firing and got worse. The spark was getting to ground on the exhaust manifolds through pin holes in boots.
Also have read where headers will destroy plug wires in short time with heat.
I have had a wiped lobe on #4 exhaust that produced just a low RPM/idle miss and does not sounds like your problem. You could remove valve covers and measure valve lift (with the lifters still pumped up – maybe engine running). But this is not an easy job. :seeya
Also have read where headers will destroy plug wires in short time with heat.
I have had a wiped lobe on #4 exhaust that produced just a low RPM/idle miss and does not sounds like your problem. You could remove valve covers and measure valve lift (with the lifters still pumped up – maybe engine running). But this is not an easy job. :seeya
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Team Owner
Joined: Apr 2002
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From: All humans are vermin in the eyes of Guru VA
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Re: Engine started backfiring... (cardo0)
Mine is backfiring through the carb. I think I may need to buy a timing gun and check the timing.
Safety Car
Joined: Feb 1999
Posts: 3,630
Likes: 14
From: Fountain Hills AZ
Re: Engine started backfiring... (rainman69)
Sounds like unburnt fuel is collecting in the exhaust from an intermittent miss and being ignited on the subsequent cycle. Usually an ignition problem but sometimes a valve problem can cause the same thing. Look for a fouled plug, bad wire or connection, distributor cap, etc..
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
Re: Engine started backfiring... (comp)
i'd check wire's first for cross fire,