Engine backfires/wont idle
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 844
Likes: 0
From: Cape Cod Ma
Engine backfires/wont idle
Now that i've figured out why this car wont start 85' (bad ignition modual) the car backfires wile i have too govern the gas to keep it running. When you bring the rpm's up it will backfire through the intake. When the rev's are down it would backfire through the exhaust. Now when i took everything apart i marked the location of the distributor and the rotor. So the timing should be close. I have no trouble code's. Im getting fuell. There is no vac. leaks. I've checked for shorts in the wiring for the knock sensor and check out that everything was connected good. The ESC, ECM, all sensors, everything on the ignition now is new from rebuild. The engine ran mint up untill acouple days ago. Then it had a mind of its own so i replaced the ecm.
Is there anything that im forgetting? Thank's Mike
Is there anything that im forgetting? Thank's Mike
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 844
Likes: 0
From: Cape Cod Ma
No no plugs swiched. I checked that multiple times. And i have a wirloom set that wouldnt alow me to easly swich em.
What has me flustered is why would i back fire through the exhaust And then you would bring the revs up alittle and it would backfire through the intake.
What has me flustered is why would i back fire through the exhaust And then you would bring the revs up alittle and it would backfire through the intake.
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 844
Likes: 0
From: Cape Cod Ma
Thank's that's what my helms sais too. But i did. Maybee im missing something. I"ll start from square one tomarrow buy bringing #1 to tdc and alinging the distributor/rotor acordingly. But i cant see why this could have change cuz i marked the rotor before dissasembly.
Thanks again i just wanted to see if im missing somthing that i may have overlooked.
Thanks again i just wanted to see if im missing somthing that i may have overlooked.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
You've got a good plan because what you describe usually means the distributor is off a tooth, especially if you removed it to replace parts. Find TDC for #1 and re-stab it making sure the rotor lines up. A long screwdriver helps get the pump drive right. Then reset timing to specs and your backfire should be gone.
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 844
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From: Cape Cod Ma
Yes wel see tomarow. I didnt compleatly remove the distributor. But i have too turn it to get at the cap retainer srews and i had to remove the rotor to replace the ignition mod.. But somewere in my adventures i could have knocked the distributer out of alingment.
Burning Brakes
Joined: Apr 2002
Posts: 934
Likes: 0
From: MO
Originally Posted by SunCr
You've got a good plan because what you describe usually means the distributor is off a tooth, especially if you removed it to replace parts. Find TDC for #1 and re-stab it making sure the rotor lines up. A long screwdriver helps get the pump drive right. Then reset timing to specs and your backfire should be gone.
Since its not wires crossed, this would be the next step!!Good Luck, if it doesn't want to drop all the way just
it with a hammer
TOTALLY KIDDING!!! 
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Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Don't forget to unplug the ESC to check initial timing. It might throw a code-so after you shut it down and plug the ESC back in you might have to disconnect the negative on your battery for a few minutes. 
Instructor
Joined: Jun 2002
Posts: 218
Likes: 0
From: Winnetka CA
I had the same problem!
I had the exact same problem two weeks ago. When I finally got it running it would fire out the intake and the acceleration was very inconsistent and would die when idling.
Turns out that:
a) my fuel filter was so clogged that it could hardly be blown through.
once that was changed it was getting good pressure, but ran really bad and found that:
b)the MAF sensor was throwing bad codes.
I am not sure if the sensor was bad before the fuel filter get clogged. Most likely the tiny wire in the sensor was damaged by the backfires out the intake. Tried a MAF from a new company called microtech that was a piece of crap. Returned it for a cardone rebuilt bosch sensor and now it is fine. I decided not to modify it because I was told by more that one person that the air rectifier in the sensors gives better readings because of the smoother air flow over the wire.
Hope this helps!
Turns out that:
a) my fuel filter was so clogged that it could hardly be blown through.
once that was changed it was getting good pressure, but ran really bad and found that:
b)the MAF sensor was throwing bad codes.
I am not sure if the sensor was bad before the fuel filter get clogged. Most likely the tiny wire in the sensor was damaged by the backfires out the intake. Tried a MAF from a new company called microtech that was a piece of crap. Returned it for a cardone rebuilt bosch sensor and now it is fine. I decided not to modify it because I was told by more that one person that the air rectifier in the sensors gives better readings because of the smoother air flow over the wire.
Hope this helps!
Instructor
Joined: Jun 2002
Posts: 218
Likes: 0
From: Winnetka CA
oh, and my timing was exactly where it needed to be. I also had brand new wires and plugs from the week before. the fuel pressure read ok while at idle (by idle I mean me holding the accelerator enough for it not to die), but when the throttle was opened it would loose pressure. It was the most confusing problem at first...
Fuel filters are like less than $10, give that a try before jumping to expensive options
Fuel filters are like less than $10, give that a try before jumping to expensive options
Last edited by amswak; Oct 29, 2004 at 11:54 AM. Reason: ...
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 844
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From: Cape Cod Ma
My maf visualy looks good. The wires are intact.
I just got done with redoing the timming. Brought 1# to tdc and marked out the rotor and such so that part is good (was pretty close) now. But im still having the same issuses.
I just got done with redoing the timming. Brought 1# to tdc and marked out the rotor and such so that part is good (was pretty close) now. But im still having the same issuses.
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 844
Likes: 0
From: Cape Cod Ma
So i was able to finaly get it to idle long enough do i could jump over to door to put a timming light on it. I had the gun on the balencer and all i could see is the timming mark go around and around and around and so on. This is with the esc connected. WTF?
