Fuel injector???
 

I have a 92 lt1, 6speed, have changed out the opti, vented of course. Opti was toast, as was the water pump, fuel filter, plugs and wires. Still has a bit of a miss, almost like it is running on seven instead of eight. Started pulling EFI harness one by one while the engine was running. When I pulled #6, it actually seemed to run smoother at idle. At about 2000rpm and then putting the harness back on, the revs go down. Checked injector, it is functioning and there is 13.8-14v at the plug in.

Is this a weak injector or could the ICM be bad? I have not switched around injectors yet to see if it is that injector or just the #6 position. The plug wires are correct.

Thanks for any ideas

..... You could do a compression check ... how does the #6 spark plug compare to others ? ... check your fuel pressure regulator .....

Update
 

Thanks for the input C409. I did switch the #6 injector with the #4 and the problem followed to the #4 cylinder. I now have a set of Bosch type 3 on order. :thumbs:

Had a similar issue and I went with the Bosch D3s, great choice. Everything runs smoother through all the rev ranges.

Cured, the new injectors took care of the problem.