[TheGeek]

End of track season wash, inspection, and oil change. When I have all the body work off, I heat it up before oil change to watch the expansion tank and do a thorough inspection. A few normal things needed to be addressed, but there's a tune problem. #1-#3 were reading all within 20 degrees around 450. #4 was reading 570. This is all at idle, so it could just be an at idle issue. Here's what I'm thinking.

1) Check the throttle body balance. If I have a lower vacuum on #4, then that's probably why it's a little lean.
2) Reset the powercommander and test again.
3) Swap #4 injector with one of the other 3. Run it and see if the temp variance moves. If it doesn't, it could just be normal. If it does, I can have the injectors serviced.
4) Use the cylinder trim function in the powercommander to richen #4 just a bit.

Can anybody find a problem with this plan?

 

[dpapavas]

Sounds reasonable. Perhaps you could also swap the #4 plug and cap after 3) and see if it's perhaps a matter of spark. It's not likely, as all the other cylinders would have to be problematic as far as I can see, but it wouldn't hurt to check.