Ok so last week I decided to pull my oil pan to fix a leak from the skid plate. All went well, but now everything is acting weird. My fuel is off pretty much everything except wot, it’s somewhat decent at idle but I got lower vacuum. My vacuum was around 7.2 give or take a few points and idle around 15-15.5. Now it’s 6.3-6.5 and idle at 14.5-15 and it runs over .5 afr’s more rich that before across the board except wot at full boost. I’ve done boost leak and even sprayed starter fluid on everything after I found no leaks. The only thing that has changed is that I don’t leak oil and I changed spark plugs. I went from bpr8 to br8. Is there anything else I can check or does anybody have any ideas or experience with this situation?

03 evo 8
110,000 miles
93 octane
aem series 1
speed density
fp red Ss and jb
gsc s2 and gsc valvtrain
Fic 1220cc injectors
walbro 400 pump
turbo back 3 inch exhaust
3.5 inch fmic and piping
ams fuel rail

 

Bump

 

Do some logging and see what the fuel trims are doing. Also I would try changing back the plugs and see what that does. Did you change the gap when you went with the new plugs?

 

Ok I’ll try to do some logging tonight. Any fuel trims in particular? And no I run at .018, should I change gap a bit since there not as far into cylinder?

 

STFT, LTFT Mid and LTFT low. I would try opening it up a bit .020-.022 should be good. .018 seems a bit smaller then i usually see recommended.

 

Ok thanks and yea I know I got them pretty closed but when I first started boosting over 25psi I kept getting spark blowout so I kept closing them till it stopped and that’s where they landed.

 

I would not be afraid of a small gap if its making power. .016-.018 works well.

I'd rather not deal with spark blow out with cylinder pressure.

 

I wasn’t worried about it when I was using the bpr8 plugs but I’ve never ran the br8s so wasn’t really sure. But whatever was wrong has returned to normal function because on my way home from work everything was back to normal which is good/bad I guess.

 

I didn't mean to say it was a problem, just a little tight for what I usually see people running at 25psi. I do 26psi all day long at .024, but everyones setup is a little different. Ideally you want to run as much gap as you can get away with and since OP added that he came to that gap through testing I agree with you that you should do what works for your setup.

 

That's good, maybe the ECU just needed to relearn the trims and top up the battery. It might be a good idea to take a peak at the Long term fuel and ISCV trims to make sure they don't seem way outta whack but if everything checks out I wouldn't worry too much about it.

 

Incase anybody stumbles across this, I have found and fixed the problem. It turns out it was a bad crank sensor. The cable had slipped Out of small metal bracket that hold it to the block and had been rubbing against the timing belt. And it didn’t become obvious until it made it most of the way through a wire and was actually showing up in misfires and stuttering. Hope this helps somebody