This is a notice to all VR4/TT owners:

When you're replacing your sparkplugs, if you're going higher than stock boost, go to a value of 32 or lower for your gap.

Last night I pulled my spark plugs figuring I'd replace them after a 600 mile mark on a rebuild. I don't remember gaping them this high but they were all around 38. I have 9:1 pistons so the compression is automatically going to be higher than stock pistons.

I had a concerning amount of hesitation around 4500+ rps which eventually I postulated might be spark blowout. I decided to buy a new set of plugs (just in case the old set were fouled) and gap them lower than whatever the current plugs were set at. From a value near 38, I went down to 32.

Almost all hesitation solved and my car feels a great deal stronger.

I might need to go down to 30ish to solve the remaining minor hesitation but I don't know if it's a fuel related thing or not. It's up in the air until I log it.

Either way, the point is, if you have a higher than stock boost setting, please gap your plugs to a value near 32.

bring that tool over tomorrow, I dont want to buy one

Yessir...I have mine at .030 no issues. One issue down, one to go?

Haha, more like an unknown to go. I'm still getting a mysterious oil leak. I need to fix that before I can get it on the dyno.

What dyno you going to? The only awd I know is a mustang dyno at Doug's Dyno Power...

There is a guy at CNC Racing who uses their space there to run his dyno. He tunes there as well as Mike Angel of Factor X.

Great info! I get a lot of cars here with "spark blowout". We gap .025-.032. Most cars come in .038-.044, even running higher boost.

Mike

Yep, gapped to 30 currently, gapping lower when I get new turbos

The last set of plugs I had installed by the dealer when my 60k was performed at 80k. When I removed them from my broken engine I found something interesting. They all looked like they were in decent shape except that those from the front bank [1, 3 & 5] all had gaps of around .042 and all those from the rear bank [2, 4, & 6] were at about .055 just like clockwork. It struck me as somewhat odd.

The only thing I can surmise at this point is that there was something different going on with the rear bank of cylinders. It may have been that the rear bank was running a little leaner and hotter than the front bank but an inspection of the injectors showed no apparent difference visually between any of them and they were all very clean. Guess the use of RedLine injector cleaner really works well. I usually put in a bottle before taking a run to San Diego or to New Mexico (my folks) thereby running a full tank full through them at one setting. Appears to have worked quite well.

Has anyone else ever noticed anything similar?

Is it common for the front and rear bank to run differently?

As a rule I always check the gap on plugs before installing them. The dealers will tell you that they are already set at the factory but DONOT beLIEve them for a second. When in doubt, check 'em.

Yeah, that Redline stuff is pretty miraculous.

I've been told that the rear bank runs a lot hotter because the air from the rear turbo doesn't have a lot of room to go anywhere or move so it just stays there. I don't know if that would have a huge effect on the engines operation but that's the only thing I can think of as far as the difference between the front and rear banks.