...so i changed my plugs to the NGK 3787( as pantherqs requested)about 2 1/2 weeks also then went logging a couple days after that and did a scan and showed a misfire(no engine light and who knows now long ago it was thrown)so i cleared it..so today i started it let it warm up for about 3 mins then started driving and then started backfiring wit some misfire and threw a engine light.....so i went to the dealer and they scaned it and came back wit a cylinder misfire on #4....i said okay fine ill be back to make a appointment bla bla bla...any ideas, tempatures were about 48 degress,not warm enough? i still have full warranty but i hate the dealers touching my car lol

Thanks guys

 

Not sure what your asking, you can either a. put your stock plugs back in and see if misfire goes away, or b. swap cyl 4 plug with cyl 3 plug and see if your misfire suddenly appears on cyl 3. If so, bad plug.

 

i had those in my tc for a week and i got misfires like crazy!!! i had em gapped perfectly and everything...when i went to take em out they were more black then the stockl ones with 40k miles on em lol, i asked vince why this was and he said some tc's like em and others not so much...so just got new plugs of the stock version

 

get stock plugs. nothing else seems to work

 

yeah thanks guys...what should i gap the stockers too?...i gapped the NGK's to .031 if i remeber correctly

thanks guys for the reply too

 

.032-.034
no prob man

 

Get them here..I just did. Best price for sure:

Click *YES* on the pop up

https://www.rockauto.com/catalog/x,c...8X%2529%2BDOHC

More Information for ACDELCO 41108

 

k thanks guys

also will misfire f*** my car up?

 

under an extreme condition, you could melt a piston

 

stock ones come gapped at .031ish, u dont have to gap them

 

non of those are stock, acdelco is stock

 

AC Delco 41-108 is made by NGK, it has the NGK part number (ILTR5D) stamped into it above the threads on the AC's. NGK 5476 is the same plug as stock.

Anyway that page also lists the AC's on it 3rd from the bottom.

 

the stock ones i pulled out of the car were .028-.041---->...idoits

 

Bought 3787s a while back. Still wondering if I should install them or not. They were a bit pricey, but I liked the fact they were a step colder while already having our recommended gap (helps keep the electrodes properly aligned if a large gap adjustment isn't needed).

I'm torn between keeping/going with stocker plugs (5476s it sounds like) versus popping these in.

 

I ran the 3787's with 24 psi for a long time no issues.
Since switching to 60% ethanol I put the stock heat range plugs back in.

 

Ok, thanks. I may try them then.

Are there any downsides to a colder plug I may not be thinking of?... Perhaps it fouls easier and that's about it?

A friend running colder plugs busted one of his pistons pretty good on a notched NLS. Any reason you can think of that it could have happened due to the difference in plugs? It took out a land. I just can't imagine tapping the limiter would cause something like that, but I can't think of anything else that it could be besides the plugs.

 

Did you see this among the various plugs listed?

ACDELCO Part # 41108 More Info {#12590701, 12617309, 12620540, 41102} IRIDIUM
SPARK PLUG .035 GAP

The AC Delcos are listed under the OLD PN as well. Trust me they are AC DELCO 41-108. I ordered them!

 

what do they mean when one step colder?....im goin to pull the plugs tommorw havent had time

 

when they fire the heat dissipates faster.

 

The rings gouging into the cyl wall due to excessive expansion from too much heat causes the ring lands to pop. The ring end gaps only allow so much expansion. Once the ends meet and they expand more the ring diameter increases more than the cyl clearance and they gouge into the cyl wall.

Too hot a plug contributes, so does knock and detonation, so does too lean or rich a mixture. Too rich in our engines causes knock too. Too much boost pressure generates more heat also.

Bill from GM has posted many times that it's due to excessive heat.

 

misfire all solved...stock plugs are in

 

one of them days I'll just replace the stock pistons with Wiseco Forged Pistons so i don't have to worry about heat like the stock one's.

 

That's only if the motor runs extremely lean.

 

okay so its been about a couple weeks now i have the same misfire CEL 1 an 4 wit my stock plugs....im about to bring it to the dealer and say fix this now