We just recently rebuild my 350 Lt1, and the motor is misfiring on the #7 cylinder and sometimes on the #5 cylinder! I bought new plugs and wires. It's still misfiriing. What are some things i might need to check?

sincerly,
jamie

 

Fuel injectors firing or not on those cyls?

Compression test on those cyls?

Optispark working correctly?

Are you actually GETTING spark?

Those would be the first things I'd check.. probably in the reverse order that I listed them in.

 

Switched injector with other cyl that were firing fine ,but samething on #7 & sometimes 5.

Will do a compresstion test tommorow.

How do you check optispark?

also airbag light on, dont think it has any thing to do with it but not sure.

 

The easiest way to check for misfiring ignition is to use a timing light. Check it first on a good cylinder and then move it to a bad one. One other thing is common and that is loose plugs. But you would hear a swishing sound, some say it sounds like ticking.

As far as the air bag light is conecerned, did you happen to disconnect the steering while the new engine went in? Did the steering wheel get turned while it was disconnected?

Compression test may tell you nothing. If so, do a leak down test.