2G tuning advise needed

Midnightride · 03-25-2008, 06:25 AM

I have searched, but I'm second guessing myself now. Here is my mod list:

2g
7 bolt rebuild with ARP head studs, new gaskets, 14b ported, exhaust manifold ported, O2 housing ported, 3" full turbo back exhaust w/ hight flow cat. 550 injectors, 190 pump, using a logger and SAFCII to tune. Balance shafts were removed. FMIC with all hard piping, 1G bov.

I had a MAFT setup but just put the stock MAF back in. The stock MAF the side cones taken out. With the stock MAF and cones taken out, before I put the MAFT set up on, the car ran fine running 20psi. I had someone help tune the car at that point.

Now since I installed the old MAF again I want to get back to that tune. I've decided to try and tune it as much as I can myself but ran into a little issue.

When I first start the car, the car idles a bit ruph( with the SAFC setting at 0, no correction). The blinky light stayes in red.

So I started to do the low settings, started of with 800, then 1400, then 2000 and stopped there for now.

at 800 I had to go +42 and for 1400 I had to go +32 or +38 to ge the STFT and LTFT to hit or be close to 0. That to me shouldn't happen right. Since I should be taken fuel away not adding right. The + means I'm adding fuel right? When I put those setting in, the blinky light show started to act normal at idle and go back and forth and not stay in red. the car also idle fine and sounded normal. Wasnt pulsating. When I took the setting in the -, the car started running rupher.

Thoughts suggestions? What could cause the car to run lean with the 550's and the 190 pump all of sutton? If that's what is going on.

RED TREAD 97 · 03-25-2008, 07:40 AM

try running it with a different confirugatoin on the honey combs. I had some strange surges after my fuel mods and found, that running the car with out the long comb on the bottom helped to resolve the problem. I hope this is what you are having issues with, cause like all things electrical issues are the worst.

Midnightride · 03-25-2008, 08:11 AM

why would it be way off though. From what i have been reading, most everyone on here with close to the same mods is adjusting it -15-18%, I'm in the +30%. Plus the honeycombs were removed before, I guess perhaps the setting were in the posetive when my buddy had it tuned. I'll have to get with him and see if he remembers what they were or if what i have now is in the right direction.

Would anything else cause this?

I guess I'm just surprised that at idle the car would be seeing that much more air or less with the side cones being gone. Maybe it was the top and bottom, I cant remember. Either way that realy surprises me.

As long as the STFT and LTFT are close to zeroed out, doe it matter what percentage I am at?

turboglenn · 03-25-2008, 10:32 AM

It would be way off because the honeycombs are meant to stabilize and keep the airflow coming in equally through all orifices so you are probably getting a lot of air that the MAF isn't seeing, thus forcing you to add fuel. I would put the sides back in, pull the little one out of the bottom if you want to have one of them out for some reason and then try and see if your fuel trims don't change to allow you to take some fuel out (-) digits

Other things that could cause this would be intake leaks (very unlikely if you take good care of your car) OR, a BOV that's open under idle vacuum. If you BOV is open at idle, just tighten it's adjustment screw to where it just seals up while idling. That will stop more un-metered air from entering and causing you to add fuel.

Honestly though, i think the only time having to go to the (+) side will hurt you is at WOT where it will cause you to go into a different timing table because it thinks it's getting more air, this could also cause early fuel cut.. So as long as you're only in the (+) side at low throttle you should be fine as long as it's in the (-) range at WOT

Midnightride · 03-25-2008, 10:37 AM

I dont mind having to add fuel, I just want to make sure I was doing everything right as far as setting and such. Adding 43%, is that bad or is there a point where I'm adding to much even though the STFT and LTFT are good?

thanks for the help by the way!

turboglenn · 03-25-2008, 10:47 AM

43% increase is kinda getting near the edge of the scale IMO. I would at least put the honeycombs back in to see if that's what's causing it, but you really shouldn't have to correct for near half of your total airflow, even if it its at idle. But by matching the trims you are doing it right for the low throttle/cruising areas.

Midnightride · 03-25-2008, 11:53 AM

I was thinking the same.

Thanks, I'll try that.