OK, someone please tell me exactly what is a MAF translator? I know what a MAF is, and I bought a Granatelli MAF, so do I still need a translator? Just trying to get the most out of my 2000 Hardtop without doing any engine work, just bolt, non-permanent mods, so any advice would be greatly appreciated. I already have a Blackwing, power duct, MAF, 160 degree t-stat, and SLP Loudmouth's. Thanks! :flag

 

Take a look at this page first for a good writeup on A/F ratios:
http://www.vetteguru.com/mods/howto/

Then, take a look at this page on what the MAFT does and how to set it up:
http://www.c5forum.com/diy/ltft.php

If I was on the fence between the GMS MAF and a MAFT, I would be returning the MAF to GMS so I could buy the MAFT.

I'm at 330/340 with the below mods and the MAFT.

F


[Modified by Flintstone, 5:53 PM 5/21/2002]

 

I was ALOT closer to 0 on my LTFT's with the GMS MAF as opposed to the stock MAF with the screen removed.

you may want to keep the GMS MAF until after you get the MAF translator and see what it does for you. :cheers:

 

Thanks guys, I really appreciate all the info and the links! :cheers:

 

You don't really want to average 0. If you look at the power/AF curve you want ride the curve on the lean side for greatest power increase. Your LTFT average should therefore be on the lean side.

 

Removing the screen works for some people, doesn't for others. In my case, it totally hosed up my trims, and caused a lot of headache. It will tend to lean out your A/F ratios, as will adding an intake, headers, or any other mod that changes the airflow into or out of the engine.

RPOZ4Z, Your GMS MAF was probably one of the ones calibrated at 5% rich. If this is the case, then this is why your LTFTs were closer to zero. If you were using the stocker with your mods, you'd probably be a little lean.

jawski, I agree with most if not all of what you said. I don't look at the overall average of the LTFTs at all. Cells 20, 21, and 22 are more or less of no use to us, so I look at the average of 1-19 for a baseline. What really shows you what is going on is the breakout, by cell, and by cell count of cells 1-19. For example, I average about 5+% RICH in cells 1 and 2 (LTFTs read -5 to -8), but LEAN in 11 through 14 (LTFTs 5 to 7). If you look at the counts of the cells, there are usually only 3 or so that the PCM spends most of it's time in (in this case 5 thru 7). I need to adjust the LTFTs for the cells I use the most, not the overall. The averages will work themselves out because of the high counts. The lean cells are the ones I'm using for most of my 50-80 mph driving, and when I go WOT, guess what, I get detonation because the PCM freezes the trim setting as soon as I hit it. The MAFT does a decent job of addressing this. I've found that the PCM occasionally "learns out" the MAFT tuning, and I'm still playing with the best procedure for getting things back to normal when this happens.

You do want to ride the lean side of the curve. When your A/F is fat, you are wasting fuel and wasting cylinder volume. In my case, I fear the pinging more than the fuel efficiency so I keep it a little fat.

I modified an excel spreadsheet someone had posted a while back for analyzing the LTFTs, O2 voltages, etc. I added formulas for computing individual cell LTFTs as well as cell counts, set it up to change the font colors for WOT and knock retard records, and so on. It's on my home system and I'll get it posted tomorrow night.

I'm nowhere near an authority on this - so take all this as opinion. I have logged probably 300 hours with Autotap though :D

 

Wow, with all that said, do you think I would be better off to just run with my stock MAF with screens or the GMS MAF? I think I will avoid the MAFT, as I don't have regular access to a dyno, and my car is basically a daily driver that I spoil and take to car shows, so I am not looking for race car type performance at the sacrifice of daily drivability. Just looking for some simple added horsepower that I can take advantage of without doing any major tuning. I think I have already given up on the idea of a ported TB as it seems like little gain for a lot of cost, but what do you guys think? Again, I appreciate all the advice! :chevy

 

Flintstone,

you're probably right about my GMS MAF being 5% rich, I was running about 5% rich before I installed the MAFt. but, I was 15% lean with the stock MAF and no screen. so the tuning is a little better with the GMS MAF.
I am on the "fat" side of the LTFT's.

I would really like to try out your spreadsheet just to see where I am at now. :cheers:

 

[QUOTE]Wow, with all that said, do you think I would be better off to just run with my stock MAF with screens or the GMS MAF? I think I will avoid the MAFT, as I don't have regular access to a dyno, and my car is basically a daily driver that I spoil and take to car shows, so I am not looking for race car type performance at the sacrifice of daily drivability. Just looking for some simple added horsepower that I can take advantage of without doing any major tuning. I think I have already given up on the idea of a ported TB as it seems like little gain for a lot of cost, but what do you guys think? Again, I appreciate all the advice! :chevy [/QUOTE

Return the GMS, pull the screen and get a MAFT. Just the simple HP you're looking for. :yesnod: You don't need to dyno but you'll need an OBDII analyzer (autotap,etc.). I was impressed with the boost I got after discussions with Kewlbrz and his white paper.

 

Here's the Excel template I was talking about:
http://forums.corvetteforum.com/zerothread?id=307147

Good Luck,

F