Safe to lean out my trims?

[boiseDSM]

CAR: 91 gsx, 16g, fmic, walbro 255, stock 450cc's, 3" maf-t...*

*The important items being the 255 walbro pump with the stock FPR and stock injectors. Now I know there is a big debate over this setup and people saying the pump will over run the FPR but I've ran with it for a long time and it seems to run fine.

THE CHANGE: My 1g mass sensor was giving very erratic readings so I had decided to do the GM-MAF-T conversion. Car runs MUCH better, smoother, no knock, instantly idles perfectly, behaves exactly like I had hoped with the MAF-T on. Best money I have spent!

THE PROBLEM:For tuning reasons, I have my wastegate hose going directly to the boost pipe without a boost controller so it opens at about 9 psi or so. Driving it around with by mtn bike in the back (so the hatch is open a little), my car smells awful (still with cat) like it is running REALLY rich. With my setup, I can see why this might be. With the MAFT zeroed out to the base settings, the MAF-T should act like exactly like the stock Mass sensor right? So why the overly rich condition now? My fuel trims look off (trying to get lean), is it safe to lean it out a bit? I've done some math and it seems with the stock FPR, injectors, and the walbro 255, I could lean it out about 8%. What are your guys thoughts? I believe even in stock form, they tend to run rich, so add in a high pressure walbro to the mix and it should be pig rich. One bad thing I've noticed is that spoolup takes FOREVER! I am not blaming the translator at all, I think it is due to the overly rich A:F ratio now. I'm a little nervous about tuning and just need someone to say "Lean that pig out!" All I have is a pcoket logger, and the MAF-T right now for tuning. Should I adjust the settings a little now or just wait for a wideband and lean it out then?

Anyone else out there running a similar setup? I am really sold on the MAFT now and think that there is quite a bit more power I can get from my car. I don't think I would touch the low, mid, or WOT setting yet, just the base settings (set for slightly larger injectors).

 

[GVR4592]

Get an adjustable regulator, it might seem like it's running fine, but it's really not. As for the tuning, it's pretty much the same for every piggyback device out there. Get your fuel trims as close to perfect as you can, then start playing with the wot tuning.

 

[My96AWD]

I second the adj regulator.

 

[boiseDSM]

Any suggestions on the AFPR? I've seen a lot of them don't have gauges for fuel pressure. Is a guage nessesary when dealing with an AFPR? I did end up leaning out my base setting and the car feels much faster. Sharper throttle and quciker spool. I've had my car for 5 years now and I think I am getting addicted to it all over again!

 

[tkelly27]

Excessively rich is bad. You may be able to compensate for overruning the stock FPR with a tune, but it will be better to have an adjustable one and less tweaked base maps.

You do need a gauge, but if you've already got one you can either put on, or somewhere else, it's not a huge deal. The previous owner put mine on the filter, very nice to have around!