Weird backfire problem
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Car: 88 Iroc-Z
Engine: 305 TPI
Transmission: T-56 Manual
Axle/Gears: 3.23 10 bolt
Weird backfire problem
I have an 88 IROC and it started backfiring last week. it would be so little I only noticed the tach jumping down. in a week it wont rev past 3000 If you push it. if you are light on the throttle it will go up pretty high with just a little popping. It does it while driving or when you are sitting in the driveway. First I played with the ignition timing but that didn't help at all. I started to get A SES light and it said bad ignition module. I replaced that and the light went aweay but it backfires just as bad. I replaced the distributor rotor because mine looked pretty bad and that didn't fix it. Then I replaced my plugs and that didn't help.
Now I had my sister watch the engine as I revved it and she saw blue sparks. There are blue sparks flying from the starter motor terminal as it backfires and now the starter barely works. I just replaced the starter a week and a half ago. they are flying from the larger terminal. MY dad took it off so Maybe there was a loose ground wire or something that I thought connected to the terminal (I have found too many of those already). There were two terminals that connected to the the larger one. I think when it's spining up the higher output from the alternator is causing the wire to arc across. Is it possible that when it arcs it's turning all the accesories/power off from the rest of the car like it does when it starts (which happens when it backfires) and kicks the gear in knocking the flywheel causing to backfire, or at least making it appear to backfire. the only other things I can really check are the cam or valvetrain, which would not be fun to replace in an engine I plan on replacing anyways.
Now I had my sister watch the engine as I revved it and she saw blue sparks. There are blue sparks flying from the starter motor terminal as it backfires and now the starter barely works. I just replaced the starter a week and a half ago. they are flying from the larger terminal. MY dad took it off so Maybe there was a loose ground wire or something that I thought connected to the terminal (I have found too many of those already). There were two terminals that connected to the the larger one. I think when it's spining up the higher output from the alternator is causing the wire to arc across. Is it possible that when it arcs it's turning all the accesories/power off from the rest of the car like it does when it starts (which happens when it backfires) and kicks the gear in knocking the flywheel causing to backfire, or at least making it appear to backfire. the only other things I can really check are the cam or valvetrain, which would not be fun to replace in an engine I plan on replacing anyways.
Last edited by miner; 03-26-2009 at 11:02 PM. Reason: finishing it
#2
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Join Date: May 2008
Location: Il
Posts: 34
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Car: 88 Iroc-Z
Engine: 305 TPI
Transmission: T-56 Manual
Axle/Gears: 3.23 10 bolt
Re: Weird backfire problem
Ok, I found a lose wire (that I have absolutely no idea where it goes, I'm guessing A/C) that was carinc across the starter. I was probably knocked loose by the original backfiring. It's a lot better now, but it still backfires some. Now I'm wondering where that wire goes. It was arcing blue, so I'm guessing it has something to do with the ignition? it comes out of the same black shielding as the wire for the starter motor from the front of the engine, and goes down the headers. There's also a sensor wire coming out of it. Could this be my problem? Now it only backfirtes when I give it some gas and not when I'm nice and easy on it.
Also I was talking to one of the guys at my auto parts store and he said it sounds like the spark advance isn't working right, but it's TPI so its computer controlled. does that mean new computer?
Also I was talking to one of the guys at my auto parts store and he said it sounds like the spark advance isn't working right, but it's TPI so its computer controlled. does that mean new computer?
Last edited by miner; 03-27-2009 at 08:53 AM. Reason: paragraph 2 added
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