Changed plugs now runs like .....

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

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

What is stock gap and plugs on the 5.3?

Stock gap is .040

But clean your MAF, that's probably your problem. A lot of people have had issues when cleaning the K&N filter. They will over-oil it and then it will collect on the MAF sensor and throw a vacuum code and etc.

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

Thanks guys .... didn't think of that. The K&N cleaning and spray application is a definite possibility. I actually through the code after I did the front 4 plugs - had to run an errand so did the back 4 later. It kind of fits - it feels like a vacuum leak .....
I'll pick up a can of GM Cleen and run that through the MAF and TB and see if that solves the problem.
Wasn't looking forward to getting a new set of plug wires - another possibility ......

I'll let you know what happens.

Toolmanz

toolmanz said:

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

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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.

Great suggestions guys. I have acquired a can of "SensorCleen" and cleaned the MAF. I also "cleaned out" the SP boots on the front 4. Car runs better and doesn't throw the code through normal driving - just when it comes to idel for more than few seconds.

So, improvement is there an I plan to do my backs this weekend when the car has cooled down for several hours.

Sounds like you were right on the money! :th_thumb-up:

I'll update once I get the back 4 done.

Woo Hoo! :th_biggrin1:She is purring like a kitten. It was the DE grease (too much) and a dirty MAF.:th_doh: Got to the last 4 plugs and now - no problemo!

I will take her out for a howl tomorrow and beat up on some rice and see if there are any problems.

As for now - we are golden.

Thanks to all of you who offered suggestions * ahem * "correct" suggestions. :th_bowdown:

Cheers
Toolmanz

toolmanz said:

Woo Hoo! :th_biggrin1:She is purring like a kitten. It was the DE grease .
Toolmanz

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Glad I could help.