C5DEMON

My car had been acting VERY strange since I got MSD plug wires and NGK TR55 spark plugs installed. I had 3.73 gears installed at the same time, but this does not seem like those would cause the issue. And if I remember correctly, the mechanic said that the plugs were gapped to a stock gap of .070.

When I am accelerating from a stop or while driving (normal driving, no hard launches or anything of the sort) the RPM's will jump a couple of thousand RPM. Sometimes 1 or 2 hundred RPM and sometimes closer to 6 hundred RPM. It'll sputter like it wasn't receiving fuel or didn't spark, then it'll accelerate slightly on it's own, like the chamber was full of fuel and it all combusted at once.

PLEASE if you have any insight into what may be the issue, I'm all ears. Thanks.

AntonioZ06

could be wrong, but from memory that gap is too big

Sidewayz6.0

They should be gaped at .040. I've never seen a gap being off make the RPM's jump around. Could be. Pull them out, and regap. See what happens.

FWIW, on my '04 I ran the TR55's and it ran like crap. I know a lot of people use them, and I've used them in other LSx's, (Usually with some sort of power adder, and a tune) but that car just didn't like them.

onlyavette

ACDelco Part Number 41-985 (12571164), is gapped to 1.01mm (0.040 inches) when the spark plug is made. The spark plug gap is set during manufacturing and should not be changed. I can't imagine why the TR55's would require 0.070 ". That is a very wide gap to jump and probably puts a great demand on the coils. Part of what makes old plugs run bad is that the wear has widened the gap.

Mr.Bill

I see 2 things that need to be addressed.
The gap is too wide.
also you need to program the computer if you have an automatic for the new shift points for the 3.73 gears. If you have a 6 speed you should be ok there.

baxsom

originally the gap was pretty wide, GM changed it. MSD wires and not running correctly. My guess is you are getting a code 0300 as well can only mean that they plug boot is not pushed on all the way. There are more than one complaint about MSD wires on here not clicking on without considerable effort. That is why the common recommendation is to get the GM red wires for half the cost and the same amount of performance.

Vetteman Jack

Do re-gap the plugs and check to ensure all plug wires are firmly seated. You also might check to ensure there is no damage to any of the plug wire insulation - I know they are new, but you just never know.

MG RED 99

Make sure those plug wires are pushed on all the way. I had MSD's and replaced them with the GM red performance wires. I never noticed any problem with the car while driving but my tuner found 2 of the msd's to be bad while tuning and doing other work and recommended replacing all of them with the GM wires.

C5DEMON

Thank you all! That's why I love this forum. I dropped the car off today to get the plugs gapped correctly and told them to make sure that the plugs are seated fully in the plug wire. I should get it back tomorrow. If I still see the same issue, then I'll switch to the GM wires. And don't worry, I'll get the car tuned here soon for the shift points on the transmission.

Robert1Stock

That and make sure to clean up your grounds, just a good thing to check in my novice opinion