Hey all. I have a problem with backfiring in an 85 2.8. It sounds like a gunshot but only if i am accelerating kind of hard and then let up. I do not believe there is any loss of power. I tried to fix it by checking the timing. it was set at about 8 and I moved it to 10 and it did not fix problem. It seems to run fine except for the backfiring. One thing i thought of was maybe egr. I just got done putting this engine in from an 87. The egr is deleted but was not on my old engine. I havent changed anything as far as the computer. Thanks for any advice.

Catalytic converter clogged? Usually this would come with a loss of power as well though.

doesn't have the cat converters. I have changed the plugs, wires, timed it and still sounds like a gun firing after hard acceleration. too much fuel? not enough air? I am not sure what to check now.

When you timed it you had the aldl pins located behind the cig lighter jumpered, correct?

If one cylinder mis-fires for a few revolutions, fuel runs through the exhaust manifold until it finally ignites. You may have arcing on a spark plug wire. You can check that by looking at your engine running in the dark.....maybe spray a water mist on it to see the arc better.

I had this problem, along with loss of power, and it turned out to be cracked vacuum lines.

How long was the '85 sitting before receiving the new engine? My '85 SE backfires and stumbles, etc. I'm sure this is mostly due to the gas which averages two years old. The engine ran fine before.

There are a lot of threads about the wild tach that has also appeared after the hibernation. Some of the people who suffered from the tach problem described my other symptoms perfectly and stated the car had been sitting a long time.

Other than some Seafoam and a new ICM (which had failed) it has gradually gotten better on its own as nw gas is added. I anticipate this taking quite a while. I'm not about to drop the tank, so I can only dilute the bad stuff a little at a time. It's so unpleasant to drive it will take quite a while to use a few tankfuls.

[This message has been edited by 85 SE VIN 9 (edited 08-19-2014).]

thanks for the replies. I did have the aldl jumped. My son said there is an exhaust leak today so I will fix that. I am gonna check the timing again and watch the engine run in the dark. will post my findings.

Possibly a leaking injector.

I haven't been able to do much with the car lately. My son is using it. He wanted me to post something specific. He said it only backfires on a quick throttle release. He wanted me to find out if that means anything specific. thanks.