I have been fighting a low idle hesitation with my 95 LT1. This motor sat for awhile until I got it installed in my project vehicle. Since then it has been a small battle trying to get everything tuned in properly. I had 4 stuck injectors. Then I had 4 that wouldn't shut. So I replaced them all. After the injectors I installed new OTVC MSD wires and NGK TR55 plugs. I have some valve train noise and it sounds like I need to set everything back to zero lash.

However, tonight I tore my intake off for a clean up and a complete rebuild. It was horrible. This motor had some serious blow by. I pulled the PCV valve and it was nasty so I replaced it along with the rubber fittings. I cleaned up the TB and all the sensors hooked up to it. So I decided to replace my plugs again since I had the bad injectors and everything was pretty bad.

I always start at the back of the block and as I worked my way towards #1 I noticed the plugs started getting dirtier. #5,7,4, and 8 were all in good shape. However #1 and #2 were really bad. #3 and #4 weren't as bad but were still pretty dirty. Yesterday I ran some Gunk Motor Flush in my motor to help clear stuff out and replaced my oil with Mobil 1 5w-30 and a quart of Lucas Oil Stabilizer. The substance on the plugs look exactly like that what I cleaned out of the intake and throttle body today. I don't understand why it is so high up on the threads though. On with the pic. This plug has less than 2 hours of run time since new.



any suggestions would be greatly appreciated. My motor is running real smooth now. I have no smoke out the tail pipe. Idle is almost 100% and is getting better since I cleaned out the TB. The IAC was just caked.

Thanks for the suggestions.

 

With even the tapered seats oily, I suspect the plugs were not perfectly sealed. Make sure there is no crud on the seat around the thread holes in the heads when you reinstall. Just a guess, though.

 

See if it's on the outside of the heads. Chances are your valve cover is leaking.

 

Nope. This has to be coming from inside. There is no sign of anything from the valve cover at all. The gaskets are new. I'm thinking I need to replace the valve seals and just freshen up my top end.