CNG Pete

Another wacky one has us stumped.

Customer said it started the misfire after a water pump was installed. I cant find ANY relationship from that job to this problem. There is no wiring near the front of the engine where the pump is.

Misfire counts on all other cylinders is 0. 7 and 8 just keep counting higher.

Leakdown test was negative for a mechanical problem.

Tried some new coils but the problem persisted.

Opened the wiring and did some jiggling and bending with no change.

I found a TSB about the ECM ground strap on the engine, but that connection is VERY clean, and I made it cleaner.

What are we missing?

-Pete

canucklehead

I had a misfire on one cylinder and it turned out to be a worn spark plug. The gap gets too big then the spark gets too weak. New plugs ( iridium not platinum) fixed the problem.

CNG Pete

Thanks. I should have mentioned that new plugs and wires were the first thing done about the problem.

-P

edac

Loose distributor, not the body but the bearings inside. Any side to side slop of rotor?

SnlpeR

i once bent the pins where the main fuel injector harness plugs into giving me no spark to cyls4 and 5

CNG Pete

Distributor? Sorry those are so last century edac.

Well problem was solved.

I wasnt the one who started this job but got sucked into it and I ASSUMED proper diagnostic procedures were followed. Nope.

The weird part about it was 7 and 8 showed misfire. The real problem was only on 8. The fuel injector connector wire had rubbed through and broken the connection for both wires! A repair of the wires had it up and running perfectly.

I assumed the injector was checked for function when the other guy changed the injector. Doh! I better not do that again. Check EVERYTHING and dont assume anything.

-Pete