So, I was going over my GT today with a fine tooth comb because I'm planning on installing my Paxton next weekend and I noticed my engine *may* be misfiring every once in a while. After I start it and the idle gets to it's normal speed, I can feel either a misfire or maybe slight detonation if I put my hand on the intake plenum. The engine has a very slight shudder to it about once every 2-3 seconds. The computer isn't picking up anything so I wasn't sure if this is just how our engines run and I never noticed before. I also have no idea which cylinder it may be. Anyone have any insight or are willing to check on their GTs?

 

Also, it might be worth noting that the difference is small enough it can't be captured with a camera.

 

It could be a vacuum leak. Check all the vacuum hose connections (and CCV). Have you tried connecting a scan tool to see if you have a pending fault code for engine misfire? If you can get to Mode $06 data on the scan tool, you can see what the misfire monitor test results are. It will show you if the engine is counting any misfires, but not enough to set the MIL.

 

Doesn't sound like an issue, especially being it's not throwing a code. It may just be a normal shudder being a camera can't even notice it.

 

I'm hoping not. Just to be sure though, I downloaded Livelink and ran a few of the Misfire per 200 and 1000 events. Is that the proper test (excuse my ignorance in all this)? If it is, I got none back so I guess it may just be a slightly rough idle and nothing to worry about.

 

Very normal.