Backfire on Cold Startup

[1991RWHP]

If i start the car up for the first time after the car has been cool ... it backfires for a few times out of the intake. When the car warms up a little bit it goes away and the car runs fine. Any Suggestions?


Also, on cold startup .. the car has a hard time staying alive... the rpms drop a ton and sometimes it even dies. After i start it up, the same thing happens.



Both situations happen on COLD START ... any suggestions on what to look for?

Its a built 306.. H/C/I .. Mild Ford "F" Cam. I will take any suggestions, thanks for your time!

 

[93project]

Bump- I had the exact same problem with my 93. TFS stage 1 cam, ported GT40 heads, intake, etc. etc. I'll be carb'd on the new engine but I always wondered what caused the issue.

 

[poulrais]

Mine did something like this at one time and the cause was a bad signal from the O2 caused by oil coming from my crank seal leak getting into the O2 plug under the car. It had something to do with the closed/open loop cycle at startup and the ECU wasn't getting the right info from the O2 sensors. Cleaned the O2 wiring harnesses and the problem disappeared.

 

[ALMOST STOCK]

I had the same problem, found out I had a vacuum leak.