Ok, I have a 1990 Camaro Rs that seems to be backfiring when I accelarate too much. I have replaced "most" of the vacuum lines. However, I haven't replaced the vacum line that is connected to the heater a/c unit this currently has a bolt in it since the heater doesn't work. If I replaced the heater a/c unit and hooked up the vac line would this help the car run any better? It's got the 3.1 engine in it. I've also been told that the computer may be bad on it. It also needs a new muffler since the last person that had it blew the muffler off when it backfired. Does anyone here have any suggestions or could lead me to find a site where I could by a computer or the heater a/c unit? I'm trying to get the car repaired so that I can drive it north by the end of the month. Would the computer have anything to do with it backfiring? I am also gettting engine codes 34 and 43 but I'm not sure what those mean it's the OBD1 codes. Thanks for the help![]

 

DTC - 34 MAP sensor circuit error (signal low indicating high vacuum)
DTC - 43 Knock sensor error
that's your two codes

idk about the backfiring though, i've never had it happen with my 3.1.

edit: if the MAP sensor is bad, it could be sending out a signal for too much air flow, which would cause it to run rich on accel. that would explain the backfiring.

 

Have your timing checked and have your fuel pressuce also checked I would almost bet it is one of these. IF its not the one of the sensors bad

 

Thanks for the code help, but I had already replaced the map sensor and I'm still getting those codes, so I'm still not sure why the carbackfires...It also stalls after it backfires, but yes, next time I'm down in Florida I'll have to take it and get the timing checked. I just don't want to put another muffler on b/c if it backfires again...there goes the muffler. Not to mention that I don't want to take it north either with the way the thing is backfiring. Would replacing the computer solve any of those problems? Thanks

 

There are several types of back fires. It has been my experience that the kind of backfire that damages a muffler is caused by a misfire of the ignition system. A cylinder does not fire the piston then pushes out a full charge of the gas/air into the manifold where is gets hit by the exhaust from another cylinder. Most of the time the fuel expands slow enough you never know it. But sometimes it’s a violent explosion AKA back fire. In a non-fuel injected car this is almost always the ignition system Old school bad condenser, bad wires, weak coil shot rotor cap even carbon tracking in the cap most of the time even with fuel injection it ends up being in the ignition system. BUT, with computer control systems it can be the computer. Since the computer controls the spark it can cause small shorts that screw with the spark modual. Back in the day we did have computer failures that caused backfires like you are talking. That combined with your codes COULD point towards a bad ECM.

Get a spark tester and test all 6 plugs for strong spark before you try anything with your computer. I would hate to see you put in an ECM just because to have a bad plug wire or cracked plug.

 

Thanks for the help! I was talking with my Uncle and he had been thinking that I had a bad computer, but was also leaning towards the cadillidic converter. Guess I'll try the comp and hopefully have it solved.

 

I'll check about the spark tester also thanks.

 

Have you changed the fuel filter lately, It sounds to me it is not gettin enough fuel...Which could be alot of whats been posted, but the filter is such a simple and cheap thing you might as well do it any way.

 

Yeah, the fuel filter has been replaced and I just had a new fuel pump put in also. The car wasn't starting. The guy that sold it to me which I bought the car for only 750$ (not a bad deal at all) said that he had replaced all the sensors ie: the map sensor which I replaced. and he was thinking that it was the computer also.

 

If anyone knows where I could find the correct computer for this car I'd also appreciate it. I tried calling Autozone, and they don't seem to have the right numbers for the computer that I have. The number I gave is: 16186641 the number at the bottom below the barcode is: 866641M911977610.Not sure if I even have the right computer module in the car.