I've got an 87 MPI car here that backfires like crazy. The timing is set right, the timing advances, and the firing order is correct.

Ideas?

 

whats the timing? 10? or 12-13. if not 12-13 try it. otherwise check plugs, and your wires for cross acrhing.

 

Ignition module in the distributer could be going bad. You can take it to autozone and they will check it for free. (You would need to pull it out of the car of course)

 

AFrikanGoodTime hit the NAIL RIGHT ON THE HEAD, it's a Ignition module and I WON"T bother testing it, just buy a new one.

 

I should add not to purchase one from autozone. Autozone sells the crapy Wells units. Get a stock A/C Delco unit- they are great even for the hotter aftermarket ignition systems. Its hard to beat good ol' Delco products when it comes to the electronic stuff.

 

NO better yet BORG WARNER, that is who makes it for everybody. IT comes with a life time warrenty!!

 

Alright so new module it is! Pep Boys used to carry borg warner, however the pep boys around here went bankrupt.....

I got a
shucks
carquest
napa
baxter
and thats about it.

 

You can buy the Holley HLY-891-103 ignition module from SummitRacing.com for $60, or you could go with an Ac/Delco module. I'd suggest the AC Delco... I'm currently running a Borg Warner module, but after having a Borg Warner fuel pump die on me, I'll never buy an important borg warner part again. I plan to replace that 2nd (lifetime warranty = free 2nd pump) BW pump with an AC/Delco V8 TPI pump when I weld on my new 1/4 panel.. the tank's gotta come down anyway.

 

Alright so I replaced the ignition module. Doesn't backfire as violently. Gonna have people tell me if they see spark/flame out the rear. Doesn't seem to backfire upfront. I wonder if it's now just the Flowmaster "Pop" that is making a like backfire sound?

But before the module change It was like an m80 was going off inbetween shifts as the rpms started to drop.

 

Did you check your timing with the white connector disconnected. If you checked your timing with the connector together it will show wrong. It's the one over by the A/C fan.

 

My book says to jump the A and B diagnostic terminals to make it not advance. And with that jumped, speeding up the engine does not advance the timing.

 

Don't want to hijack the thread, but my 2.8 backfires too - If I've got 'er floored, and I'm shifting really hard around 5k or so, it makes a big pop. Could this be an ignition module too? Or timing?

 

If your shifting at red line that may be the computer cutting the igntion to protect the engine.

 

Twilightoptics DON"T EVER start your car with A and B diagnostic terminals connect, you will FRY your ECM.

 

Okay here is the book saying it:
My chilton says:

Under 2-10 Engine performance and tune up : Ignition Timing

5. C. on 2.8L, 5.0L, and 5.7L fuel injected engines, with the engine running and all accessories off, use a jumper wirh to connect diagnostic terminal B and ground terminal A of the 12-terminal assembly line diagnostic link (ALDL) usuall located under the left side of the instrument panel...

All I can think of is that I'm a tooth off on the distributor, or, the engine backfired so many times with spark and flame through the flowmaster, that the flowmaster is messed up now.

 

Right... with the engine running... but don't leave that jumper in when you start the engine!

 

I didn't start it with

 

I ate some red beans and rice lastnight from Popeyes and I tell you what I was doing some backfiring !