backfire

[Bigot Bledsoe]

my car recently began hesitating under acceleration and progressively started to backfire. i replaced the plugs, wires, coils ,O2 sensors, ran sea foam thru the fuel system and engine and it still backfires(pops) when the car is running regardless if it's at idle or under acceleration.

I began unplugging the injectors one by one. The backfire stopped when i unplugged the injector on cylinder 3....So, where should I go from here?

 

[mike & juli]

You have a Viper? And, you're listed as an enthusiast? PM your VIN# to the moderators to upgrade you to Viper Owner, and join the VCA...you'll get MUCH more help that way~! (1-800-998-1110, or vipermagazine.com, have your VIN# handy for both)
(moderators: lee00blacksilvergts, vipertony, citysnake, leslie, big-n-italian, kcobean)
Good Luck...also maybe call Chuck Tator 1-914-763-3136...tho he's in a fight for his dealership right now. Call and find out! ~juli

 

[Martin]

my car recently began hesitating under acceleration and progressively started to backfire. i replaced the plugs, wires, coils ,O2 sensors, ran sea foam thru the fuel system and engine and it still backfires(pops) when the car is running regardless if it's at idle or under acceleration.

I began unplugging the injectors one by one. The backfire stopped when i unplugged the injector on cylinder 3....So, where should I go from here?

What year is it and how many miles?

My first guess is you have a bad exhaust valve. Have you done a compression check on it yet? You might have a burnt valve, or a busted spring.

 

[Steve-Indy]

Anything different on plug #3 that you removed??

I might swap in a new injector to #3 cylinder as a test.

 

[Bigot Bledsoe]

What year is it and how many miles?

My first guess is you have a bad exhaust valve. Have you done a compression check on it yet? You might have a burnt valve, or a busted spring.

01, 60k miles. Have not done a compression check

 

[Bigot Bledsoe]

Anything different on plug #3 that you removed??

I might swap in a new injector to #3 cylinder as a test.

nothing different. plug looked the same as the otherss

 

[Bandit3]

A mechanic is needed. As mentioned, swap the injector and see if the problem goes with it, if not, a vacuum gauge will show a burnt valve and it's easily performed. Then a leak done test should be done. Don't think I've ever heard of a burnt valve on this site. Good luck. If it is a burnt valve, look for a lean condition in that cylinder--vacuum leak etc.

 

[dave6666]

Can't exhaust leaks show themselves as backfiring out the exhaust?

 

[Bigot Bledsoe]

A mechanic is needed. As mentioned, swap the injector and see if the problem goes with it, if not, a vacuum gauge will show a burnt valve and it's easily performed. Then a leak done test should be done. Don't think I've ever heard of a burnt valve on this site. Good luck. If it is a burnt valve, look for a lean condition in that cylinder--vacuum leak etc.

Swapped the injector and no luck, ruled that out so now i'll move on to the next steps. Thank you

 

[Martin]

Swapped the injector and no luck, ruled that out so now i'll move on to the next steps. Thank you

You might also check the exhaust manifold right at the #3 cylinder. If you have a crack in it or some other significant leak, it could cause some backfiring because of the uneven backpressure.

 

[bluesrt]

next time instead of swaping the injector,listed to it with a auto stethascope,if it isnt ticin,it aint workn.

 

[RobZ]

Backfire out the exhaust is not a backfire, it's an afterfire.

 

[dave6666]

Backfire out the exhaust is not a backfire, it's an afterfire.

But can you tell one versus the other by sound? Or maybe provided further definition of what a "backfire" is? Enlighten the masses?

 

[ViperTony]

How backfire up front, say before the cats? Is that pre-backfire? I ask that because I was getting pre-backfire when I had an exhaust leak on crappy Borla headers.