flaresniper

with the stock turbo on my s4 im using right now and the 550cc primaries and the 680cc secondaries, and my megasquirt, it seems as the stock stock temperature plugs are getting fouled up maybe. should i switch to a one step colder plug (im running around 10-12lbs of boost), or should i just stick with the stock temperature plugs??

Icemark

Actually plugs will tend to foul more; when running colder plugs when starting and running at lighter loads.

So if you are having a fouling problem the last thing you want to do is go with a colder plug.

You go with a colder plug if you are having detonation issues (knocking/pre-ignition).

flaresniper

ah. so stick with the stock plugs then eh? the only other reason we are considering going to a colder plug is i seem to have a mis-fire randomness, so i would wonder if that would cure it.

Icemark

well if you are having fouling issues, you need to either re-program your fuel mixture, adjust your timing or use warmer plugs.

A random mis-fire at idle on plugs suggests bad plug cables, bad plugs (gap is too large for the energy needed to light the plug) or other plug issue.

turbine

iTrader: (1)

you sound like you are running to rich at idle that will give you a little misfire and it will foul out your plugs

flaresniper

this was the first megasquirt so i dont wanna go boom.

whats a good gap to have the new plugs set at?

The Griffin

lf your plugs are fairly new and not been fouled with trying to get the megasquirt up and running i'd look at other reasons for your misfires,colder plugs won't do anything.You may be picking up noise in the ignition if all the rest of the ignition components are in good shape.Just a thought.

Icemark

The stock gap for the FC is .028. If you are using the standard/stock NGK plugs you can not adjust the gap.

But adjusting the gap, if you have an adjustable gap, what to adjust at... well that depends on what you are doing on a lot of things.

For example as a rule of thumb:
(from the stock factory gap)
You change your plugs often= +.003
You leave your plugs in for 30K miles= -.005
You have a CDI system and new spark plug cables= +.005
You drive Max throttle all the time= -.002
You drive for max gas mileage (soft ***** foot driving)= +.005

So once you get that rough estimate then you can next make adjustments based on driving style. Drive a couple tankfuls of your normal driving style and get a good gas mileage estimate figured out. Then increase the gap by .005 and drive another 1000 miles or so (about three tanks of gas) if you saw an increase in mileage, increase the gap again by .005. If you saw a decrease in gas mileage , descrease the gap by .005.

Drive another 1000 miles and repeat. Ideally you want to get to the point where if you increase the gap by .005 you get a decrease in mileage. For example if the gap is at .040 and you are getting the better gas mileage than if you were at .045.

The .040 would be your optimum gap for power and gas mileage (your actual gap might vary- .040 is just used as an example).

flaresniper

score. that helped out alot man.