LY6 swapped 99 Trans Am. Stock LS3 intake manifold, rails and injectors. Random miss at low RPM and low throttle. If I punch it, the miss goes away and pulls hard. Car has a PTM throttle body, long tubes, GM 85MM MAF. It also has a Tick Street Heat Stage 2 LS3 cam.

I've swapped 02 sensors, MAFs, plugs and coil packs. No change. I am using the EV6 to EV1 injector harness adapters. Just the pugs, not the extensions.

Fuel pressure is good at the rail. Next step is fuel filter. Could it be tune related? I'm at a bit of a loss at this point. Any ideas?

 

Anyone?

 

Vacuum leak?

Plug all PCV hoses and see if a piece of paper will stay over the oil filler opening with the motor running. This will help diagnose an internal vacuum leak.

Injector orings?

Injector matching?

 

I'll try plugging the PCV hoses and see what happens. If it was orings or matching, I figured the issue would be all the time vs low throttle/low rpm?

Thanks for the reply.

 

Update. Took RixTrix's advice and looked into the o rings. Found that I had a couple injectors with LS1 rings. Obviously, that's not good with the larger LS3 o rings needed. I swapped them all out and the miss has gotten significantly better, but it's still there at cruising speed and a little bit on slight acceleration. Any other ideas?

 

Also, now I'm second guessing my PCV routing. I have the rear port on the drivers side routed with a PCV valve going to the throttle body, then the port on the front of the passenger valve cover going to the intake manifold.