I start my car and sometimes it idels for a bit and other times this happens immediatly. I start the car and it seems like it shoots compression out of the carburator. Sometimes its air and a little smoke other times its a flame. Ive taken it to 3 mechanics and none of them can tell me whats wrong. When this happens and I try to start the car it does it over and over. Please help.

 

So it's back firing out of the throttle body? It's probably timing related, have you checked your timing? What is it set at? How many miles are on the engine? How old is the timing chain? - The reason I ask is because it's possible the chain is worn and it's jumped time which is causing your backfire. Does it happen everytime or just once in a while? Also you should probably find a real mechanic..
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Is this the 91 rs in your sig? I'm asking because you say it's backfiring out of the carb and it says your car is tbi.. just making sure we're talking about the same car..

 

yes its a 91 tbi its backfiring out of the ports that the fuel sprys into. The car does it all the time sometimes it idels for a while then does it and other times it happens immediatly. I was told by 2 of the mechanics that the chain looks to be in good shape and my timing is as good as it gets. One of the mechanics owns a f-body trans am so I lean towards what he says. the engine has 160,000 miles on it.

 

Did you play with the rockers before this happened? It may be an intake rocker(s) too tight and slightly hanging open.

 

someone sent a private message. Sorry cant figre ot how to reply but it idels real smooth at times and it idels rough at times so im not sure. I will talk to my mechanic about that thanks
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no I havent I installed this motor from another 91 camaro that I had it was a easy quick swap out and the motor ran perfect in the other car and has gave me hell in this one.

 

how long since the swap? Has it done this ever since the swap
what all di you swap from th eold car with the motor? dizzy, TBI unit?
thinking maybe a fuel issue maybe dumping to much gas in maybe a vac leak of somekind

 

a few months it drove for a while and the dizzy went out so I replaced it, the spark plugs the coil the dizzy cap the oil pressure sensor and a few more things i cant think of and it ran for a week after I replaced all that and now its this crap. What would cause it to dump to much gas? Im believe no vaccum leaks I did replace all the vaccum lines also.

 

how did they check the timing chain? Did the actually pull the water pump drop the pan down and pull the timing cover? How many hours did they get ya for all that?

 

Do a compression test or a leak down test. That would rule out a burnt exhaust valve.....

 

not exactly sure how thats done but if the car has to be running well im screwed

 

no you dont. To do a compression test you just have to have the motor being able to turn over.

 

Well are you sure that your dizzy isnt off a tooth? Those damn things can be a pain sometimes to get right. but i would take it back out and put it back in again.