Thread: Changed plugs now runs like .....

Resetting a pcm resets all the learned idle, fuel trims etc etc.

What is stock gap and plugs on the 5.3?

Yea clean the MAF, be sure to get MAF cleaner though. Even electrical parts cleaner can mess up a MAF.

Originally Posted by toolmanz

I have an 06 GXP and have really left it stock for now - except a K&N intake. It has been running strong until now.

I did a bunch of maintenance to it as I am taking her on a long trip in a couple of weeks.
Here's what I did: Replaced the spark plugs (original stock ACDelco) and replaced with NGK 5IX gapped to .040. Dumped some DE grease into the boots. Also cleaned my K&N cone. Reset the ECM (battery removed).

It has thrown a code and haven't had time to read it yet.

Here is what it's doing: runs like *beep* at idle - quite rough - (I feel like I'm sitting in a top fuel car with an insane cam ). Once you get going down the road it's fine .... taking off from stop is rough until you get the revs up. Ok on the highway. Tranny is shifting later than before (but that could be me babying it).

Sounds like a vacuum leak or MAF and TB need a good cleaning. Or is it something else?

Any insight would be helpful. I will read the code and see what it tells me ....

Cheers

There is your problem; well I’d give it about 90% chance just going off what you have written.

If this information is known I apologize but….

I have observed MANY times in the past, on this site and in real life, people think DE grease is conductive. Well it isn’t, it is more of an insulator than anything else. If you put more than just a hint of it on the inside wall of the boot you’re do it wrong IMHO. I use a Q-tip to apply my DE grease FWIW.
I'd start by taking off the plug boots one at a time and cleaning the top of the plug and the metal clip in the boot.

Good luck man.

^ This. There is a reason the single use pouches most auto places sell is a very small amount. Its MORE than enough to do a v8. As with most things a little goes a long way and if you used alot it could be part of the problem.

I would suggest you clean some of it out, use just a hint on the final 4 and install them, use the cleaner to spray clean the MAF (no q-tips or brushes, just spray and let dry) and see if it runs better. If not then check the plugs and make sure non are cracked (had that happen either prior to or during install) and they are ALL gapped properly. You can never be too careful or precise when it comes to cars.

Originally Posted by toolmanz

Woo Hoo! She is purring like a kitten. It was the DE grease .
Toolmanz

Glad I could help.