Bad miss
Thread Starter
Heel & Toe
Joined: Jul 2020
Posts: 17
Likes: 0
From: Ohio
Bad miss
1987 bone stock. Drove in, in the rain, running great. Next day, starts runs really bad, missing badly, black smoke. Waited a while, then, no start. Next day start, runs bad. Plugs less than 500 miles. I put in new cap, rotor and module.40 PSI fuel pressure. Starts okay missing bad at idle, will rev pretty well. I noticed I have a hole in the right pre cat, but I think it's an old hole. Any idea why it is running so bad.
Thanks
Thanks
Melting Slicks
Joined: May 2014
Posts: 2,895
Likes: 592
From: New Port Richey FL
Since you said you were in the rain, either pull a Fuel sample from fuel rail or Syphon/draw it from the bottom of tank.
Get sample into a clean clear jar if you have water in it you will see it, they separate very quickly.
Now the usual how would it get in, the drain in the filler area gets clogged and drowns the cap.
Get sample into a clean clear jar if you have water in it you will see it, they separate very quickly.
Now the usual how would it get in, the drain in the filler area gets clogged and drowns the cap.
Racer
Joined: Mar 2020
Posts: 387
Likes: 148
From: Langton, Ontario, Canada
2025 C4 of the Year Finalist - Unmodified
Use an infrared temperature gun to find your miss. Point it at the exhaust ports, where they meet the exhaust manifold. They'll all be hot, except the misfiring cylinder, which will have a cool exhaust port.
