Thread: Question on spark plugs

So I installed my PCM from 3800 performance (yay) and now I've got a serious case of the knocks. Octane booster didn't help. The sticky suggests different spark plugs what do you guys recommend or have had success with? I know I will need some kind of exhaust mod too.

What make, model car? Which engine? What mods exactly? You will have to drop one heat range probably, maybe even two. We need to know this stuff to get you in the right direction....

Yeah that's my question to drop a heat range what do I ask for at the parts store? I want to go there knowing because I doubt they would know.
The engine is stock just my k&n filter and the pcm. My GT is N/A. I had the car out a little more this afternoon and the knock wasn't AS bad I guess the octane booster got mixed up but I can tell this PCM isn't for a stock setup.

Are you running 91/93?

Well I forgot and filled up with 87 before I got my pcm. With the octane booster and some stabil fuel I put in I should be at 91.

Doubt it octane booster normal will only raise it by 1 or 2. Get some premium in and you should be fine. How many * do you have?

I don't know I don't have any scan tools. It was loud though at first. I'm just paranoid I had a stock 94 Bonneville SE that eventually blew a piston into 3 pieces.

Yeah stay out of the throttle if you can hear it knock. You really need to get something to scan with. You shouldn't mod not knowing what is going on inside your engine.

what type of spark plug do you want to run? copper, platinum or iridium? I would also run out the gas that you have and see what happens when you fill up with premium. If you can actually hear the knock, that is obviously not good. If when you fill up with premium you are not knocking(which you may or may not be if you can't scan for it) you should not drop plug heat ranges. You only drop heat ranges if you have to, as doing so if not knocking will cause the car to run less efficiently and to get poor gas mileage.

from what ive been told on here, you dont need colder plugs on an n/a engine. i have stock plugs (hell, probably the plugs that came with the car) on my engine with the 3800performance pcm and i am just fine. i also have an intake, plog, and opened up exhaust. do you have any of those things yet? or did you jump right into the pcm?

I jumped right in..probably not the first mod to make.
I'm gonna drive out my tank and fill her with 93 before I fly off the handle anymore.
I regret buying the k&n filter I should have made a FWI. I'm sure I could ebay it to some one that doesn't know any better. I wasted my autozone $20 off on it too.
Thanks for all the info/help guys.

ah, if i were you i would take it easy on her until you get that exhaust opened up a little bit

edit: i just noticed you have an 04; i dont know if those have the "u-bend" or not but if so, that should be the first thing to go

the 04's do not have the ubend as that is the first year that they were deleted. all series three 3800 motors do not have the u bend. That is why he needs to scan to see if he needs a plog or downpipe. It may be OK without it, but it is hard to say without scanning it.

I'm figuring on needing a plog or downpipe. I want to keep the back end of the exhaust stock though. I am def a noob when it comes to this scanning talk. Where/who does that?

you should look into getting an aeroforce gauge........they are very useful for many, many things including monitoring things and checking/clearing codes Please see here:Aeroforce Technology Inc | Products - Interceptor
Or if you know someone local that does tuning, they can scan for it also....

Sweet. When I sell my motorcycle I will look into one of those.

Ok, so I know you guys aren't losing sleep over this but I'm bored and figure this would help anyone that's a PCM noob like me.

So, around the 2nd day of driving the knock pretty much went away. It also took about 2 days of driving to start to notice any real difference as far as firmer shifts and improved performance. It actually caught me off guard as I went to pass someone it skipped down and I blew by them. So I fill up with premium today and I did a little MPG test. For work today I drove 125 miles 75% highway and got 29.6MPG!
I had only been getting around 25-26 and only hit 29 twice when I was on the turnpike and it was ALL highway. I'm really impressed. I guess it just needed driven a little for the PCM to figure things out.

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Originally Posted by Liquifire

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now i understand how you get 1300+ posts in only 3 months.....

i rememeber my pcm took a little bit of driving to "learn" but there was never anything major like engine knocking..... your tranny shifts like a freakin rock star now doesnt it??? glad you got it fixed