90 Bronco 5.0L w/ 4WD

I have had a long running problem w/ poor acceleration and backfiring once the engine fully warmed. No missing but engine would practically die under acceleration and usually lightly backfire through the throttle body. I discovered that retarding the timing a few degrees from 10 BTDC to about 6 BTDC helped a lot but did not fully cure. Engine idled fine and cruised at steady speed OK.

I checked every system that I felt could potentially cause this problem w/ no faults found.

No codes are set.

I finally decided to replace the distributor, since the issue appeared to be related to the timing w/ a warm engine. I purchased a used distributor from an 86, 302 mustang on ebay. It looked pretty rough when I got it, but I cleaned it up, new oring and installed.

It appears to be the cure. Engine will now accelerate reasonably w/ timing set at 10 BTDC, and no backfiring.

My speculation is the timing sensing device in the distributor was somehow sending a faulty signal that caused an improper timing response by the ECU.

I've seen similar problems posted on this forum, and hopefully this may be of help to others.

Regards

 

Glad ya found ya problem, i replaced mine with a dist from msd , a billet wow what a difference that made