Checklist before getting a tune?

A close gap might not make an adequate spark to light off the mix.  Too wide of a gap might get let the spark get "blown out" before really igniting the mix.  That's usually the concern when running high boost and wanting to close up the gap.

I check the gap on plugs before installing even if they're supposed to be at the right gap out of the box.  I use feeler gauges to check gap.

Posted by: @nocoolname

A close gap might not make an adequate spark to light off the mix.  Too wide of a gap might get let the spark get "blown out" before really igniting the mix.  That's usually the concern when running high boost and wanting to close up the gap.

 

I check the gap on plugs before installing even if they're supposed to be at the right gap out of the box.  I use feeler gauges to check gap.

What gap size are your plugs then?  Did you buy NGK BKR6E or NGK BKR6E-11?

.043 is what I gap mine to.  It's stock ecu, intake and exhaust.  I probably have just the 6E plugs as I don't have the 11 suffix in my notes as I don't remember the last time when I bought plugs.

@scotched Too large a gap and you will have misfire at the highest loads (lookup Paschen's law).  Dual Fine wire allows a larger gap based on this.  Too small and you will have poorer cold-start and more misfires whenever the fuel/air mixture is marginal due to internal EGR (like at idle with a lot of valve overlap as you might have with hot cams)

Some things of note:

1. When I ran the PFC (base tune) on my dying C56, knock was all over the place.  It seemed like it would randomly spit out value of 20-50.  I put the stock ECU back in for a couple of months to make sure I wasn't running any lean/rich codes.

2. I just put the PFC (base tune) back in after switched to C60.  Behold, I can't get a knock value above 25.  I guess my old trans made a ton of vibration when I would let off the gas.  I had through it was my downpipe rattling a crossmember or something, but with the C60 that noise is gone.  I'm going to get a tune in a couple of weeks - but I just thought that was an interesting observation.