Reoccuring problem after backfire
 

Hi guys, wondering if anyone has any insight on helping with my buddys FC. Its an 86 SE. Here it goes:

One night me and my buddy were racing, and when we race he tachs out to 8k. When he hit fourth, he let out a massive backfire. Ususally we dont think anything of backfire, were used to it. Well later that night, it started. Above 3k in any gear, the car would start missing really bad. Sometimes its 6k other times its 7k, but it has happened as low a 3k. Now this is the problem with the problem. It doesnt do it all the time. Sometime it will run fine, but most of the time it misses. Its a pretty bad miss, almost a cut-out sometimes. SO, we went to work. (fyi: we did not consider the backfire having anything to do with it, but noted it anyway) We have done the following:

Changed plugs, wires and coil packs
Grounded the crap out of everything
Checked vaccum lines
Check injector connections
Swapped MAF
Swapped ECU

We have run out of tricks in our bag. Anyone have any ideas. We now are wondering is something internal was damaged when the car backfired? Thanks for any help or speculation!

Joe

Did you check your timing or TPS sensor? alot of issues such as you described can lead to both things.

All i know is that he has the timing advanced. We have a parts car, so we will swap both parts out. I think he said he may have swapped out the tps, but Im not 100% on that.

yea, I heard that misadjusted tps can cause backfires and misses.

Use a voltmeter, set it for Kohms, and use the probes on the green and black wires I believe. Check out fc3spro.com to make sure thats right.

The TPS should sweep perfectly from 1Kohm to 5Kohm, there should be no dead spots so to say.
Once you do that, adjust the timing so its dead on, and then see if it does it again.

after messing around some more, we ran the car without the tps pluged in, and didnt have a problem, it ran fine. Does that mean its the tps, or a something else. because I thought the car needed the tps to operate properly?