Help - mild hicups & backfires during engine decel
Thread Starter
Instructor
Joined: Jun 2002
Posts: 145
Likes: 0
From: Downtown
Help - mild hicups & backfires during engine decel
what causes these noises when decelerating, and more pronounced when using engine to decel car?
Timing or Carb? I'm running a stock 350 w/ edelbrock performer 4 barrel & HEI.
thanks guys
Timing or Carb? I'm running a stock 350 w/ edelbrock performer 4 barrel & HEI.
thanks guys
Racer
Joined: Dec 1999
Posts: 267
Likes: 0
From: Seattle, WA USA
Re: Help - mild hicups & backfires during engine decel (14-Paul)
Look for vacuum leaks. "Backrap" is often caused by a lean condition. First place to look is headlights & heater/AC. Disconnect & plug all the vacuum hoses & check to see if the noise is gone on de-cel. If so, re-connect them one at a time.
Make sure you know what you are doing with regards to choosing the correct vacuum-advance port on the carb and setting up the distributor advance curve. (if not, I have one name for you - "Lars". Do a search)
Make sure you know what you are doing with regards to choosing the correct vacuum-advance port on the carb and setting up the distributor advance curve. (if not, I have one name for you - "Lars". Do a search)
Melting Slicks
Joined: Apr 2002
Posts: 2,103
Likes: 0
From: Tucson AZ
Re: Help - mild hicups & backfires during engine decel (soundguy)
Check plugs and wires. Mine back fired after a hard accel when letting off the gas. Wires solved the problem.
Also check fuel mixture. The back fire (if I remember correctly) is gas burning in the exhaust. Too rich a mixture or incomplete burning will cause it.
Also check fuel mixture. The back fire (if I remember correctly) is gas burning in the exhaust. Too rich a mixture or incomplete burning will cause it.
Burning Brakes
Joined: Mar 2002
Posts: 803
Likes: 0
From: South San Francisco CA
Re: Help - mild hicups & backfires during engine decel (14-Paul)
Try gapping your plugs at .045" and see if it goes away. I did this to my car and it has never run better. I think it's the bad gas these days.....
Le Mans Master
Joined: Aug 2000
Posts: 6,362
Likes: 7
From: Brazos TX
Cruise-In IV Veteran
Cruise-In V Veteran
Re: Help - mild hicups & backfires during engine decel (14-Paul)
Do you have tubular headers? They will do this even when the engine is properly tuned.
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
Re: Help - mild hicups & backfires during engine decel (Surfer69)
Could be leaky exhaust manifold gaskets. Happen to me after header installation.
Safety Car
Joined: Feb 2000
Posts: 4,977
Likes: 38
From: Massachusetts , USA,
Re: Help - mild hicups & backfires during engine decel (MNJack)
Had same situation, pooooooooping on deceleration, it was due to exhaust donut leaking, resolved via :smash: new donut..worked for me.The Dog :seeya
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