rastarocket

I did some bolt on stuff and a tune, and now if it's in park and i rev it to 2000 rpm or above and hold it there, you can hear a sputter. if it's just at a normal idle it wont do it, and also if im driving it wont do it. it only seems to make the noise when there's no load on the motor and it's held at about 2000 or above. Im not sure if it is exaclty what a normal sputter sounds like, its like a popping noise. I'm thinking coil packs maybe or plugs, or both.. any ideas here??

cliffyk

Some good news is that if there were any real problem, it would not idle and drive well.

Will it rev higher than 2000 rpm in neutral? Could be the neutral rev-limiter has been set to 2k rpm???

One other thought, a lean mixture is more difficult to ignite and revving in neutral would create a leaner than normal AFR. So, you may want to pull the COPs and examine the boots to see if they are burned smelling or show signs of hardening or arcing--these conditions would reduce the power available to fire the plugs.

Speaking of which, how many miles on the plugs? What make and model are they?

rastarocket

it will rev above 2 grand in park or neutral, but it starts making that back fire, sputtering, what ever you wanna call it noise, at 2 grand. and i noticed it also does it very minimally when im on it pretty good and then get off the gas all the way, as the tack drops back down i can hear maybe one little "bup" but thats the only time it might do it while i drive. for the most part its all when there is no load it seems like. the car has 58K on it and the COPs are original, so that would make them motorcraft right??

cliffyk

Then I would pull the COPs and check the boots, and while they are out replace the plugs--the service interval for the plugs is 100k miles, but that doesn't mean you have to wait 'til then.

The car may only have 58k on it, but both the boots and the plugs are 7 years old now, and especially with things made of rubber time takes its toll as well...

rastarocket

yeah ok, ill do that, although im not very familiar with COPs, what do i want to look for to see if they need to be replaced?? and as far as the plugs, if i buy a set from autozone or a place like that, maybe A/M, for my car will they come with the propper gap, or will i need to gap them myself? if so, what is the gap?

cliffyk

"see if they are burned smelling or show signs of hardening or arcing"

A common misconception is that plugs come pre-gapped. While this is to some extent true, as modern manufacturing techniques allow makers to produce plugs with very similar gaps, the gap needs to be checked to make sure it is correct for your car.

from NGKs FAQ (click here):

Q: Do I need to set the "gap" when installing a new set of plugs?

A: Maybe. A spark plug part number might fit hundreds of different engines from many different manufacturers. Although the NGK factory will set the gap to a pre-selected setting, this may not be the right gap for your particular engine.

For our 4.6L 2V GTs the proper gap is 0.054" +/-0.002".

I run Champion plugs in everything we own, the stock number for our cars is #3401, a single platinum design same as the OEM plugs. They are $3 or so each at most FLAPS...

rastarocket

Yet again, you help me out! thanks for taking the time to give me a good explanation. I very much appriciate it!