Gm maft tuning

Spool'n Spyder · 04-28-2005, 08:50 AM

I just got my gm maft setup on my car and was trying to get it tuned but i'm having some trouble. Here's a log from last night...

rpm timing o2v

1736 10 .94
2128 8 .98
2604 4 1.00
3200 8 .96
3888 13 .90
4520 8 .96
5200 11 .96
5832 13 .98
6284 15 .96

Why does this look so crazy? I had gotten pretty confident with my safc
tuning skills, but I never saw the numbers jump around like this. If I
understand right, the 3888 point is the only part i'm running good a/f
ratio?

Thanks, Nathan

drivemusicnow · 04-28-2005, 11:53 AM

You're running very rich, which may be causing "rich knock" i don't know if the ECU would pull timing for that though... either way, lean it out a bit.

Spool'n Spyder · 04-28-2005, 12:05 PM

Do you think I should lean it out with the wot knob on hte maft or start the tuning from here with the safc?

whitegst97 · 04-28-2005, 06:27 PM

I'm guessing your turbo gets full boost at around 3k, that's where it took the biggest dip in timing, but the 02 volts where extremly high at that point too. Can you give us more info, what turbo, fuel mods, MAFT settings?

Stapl3 · 04-28-2005, 06:30 PM

Lean it out a tad in the middle.

Up top doesn't look so bad. timing at 15 on a 2g isn't unusual. What size injectors do you have?

Spool'n Spyder · 04-28-2005, 10:46 PM

I'm running a evo III b16g turbo, mani, and o2 housing. I have a walbro 255, 450's on a stock n/a spyder fpr. I now have a sbr 2g fmic j-pipe, so the boost source is t'ed into the bov vacuum line and I get boost spike up to 14 psi. My maft settings are aux-4 base-0 idle-5 mid-2 wot-c. Remeber now, i'm a 2.4L sohc with a turbo ecu, knock sensor, and 450's.

Thanks, Nathan

Stapl3 · 04-29-2005, 02:41 AM

Yeah, you're fine then.

Lean it out a bit in the middle and repost the log.

Spool'n Spyder · 04-29-2005, 12:52 PM

I did a little tuning with the safc and here's the latest...

rpm timing o2v

3160 9 .94
3912 13 .84 I dont know what happened here, my tps was 95%
4632 9 .94
5308 12 .94
5816 13 .96

I was hitting 1600 on my egt gauge by the end of that run (not even to 6000 rpm's). Sorry about the spot where I let off the gas, I dont know what happened. What do ya make of this?

Thanks, Nathan

1fast97gsx · 04-29-2005, 08:45 PM

You need to post a 3rd or 4th gear log from 2000 rpm to redline at 100% throttle the whole way.

Spool'n Spyder · 04-29-2005, 11:23 PM

Here's another one....

rpm timing o2v

2356 13 1.00
2848 7 1.02
3440 11 .96
4132 14 .92
4744 9 .98
5368 12 1.00
5952 16 1.00

Still looks like i'm running rich, right? I've leaned it way out from where I started. Could something be going wrong here or am I just running THAT rich.

Thanks, Nathan

1fast97gsx · 04-30-2005, 11:03 PM

In all your logs you are getting mad timing pull between 4000 -4500 rpm. When do you reach full boost? You appear to have a boost leak or some sort of fault with the O2 sensor from what I can tell. Although the translator alone is not the best way to tune, it should still be fairly linear as far as your a/f goes. You have the dip in timing around the same rpm in all your logs which doesn't make sense. A turbo like mine hits full boost around 4300 - 4500 so I should see the timing curve you are seeing, but not you. Overall you are rich, however at that timing pull point you are on the borderline of stoich and lean imo. I suggest doing some rpm mode tuning and just leaning out the upper rpms since that's what's really important at wot.

andymoraitis · 05-01-2005, 12:50 AM

Quote:

Originally Posted by Spool'n Spyder

I have a walbro 255, 450's on a stock n/a spyder fpr.

Somebody please correct me if I'm wrong, but running a 255 on a stock FPR will overrun that thing big time and likely make it run pig rich. If there's no way to turn down the fuel pressure then you may be chasing your tail when it comes to leaning it out.

Hope that helps,

Andy

Spool'n Spyder · 05-01-2005, 08:07 AM

Yeah, I was thinking the boost leak thing too. I have'nt had a chance to do that, i'll probably do that today. The last log was leaning it out with the safc and I do see that stoich/lean timing pull. Should I richen it up right there or leave it alone and lean it out in the other places. Is it knocking really bad or is it ok (I know that NO knock is good), but is it like toasted engine knock?

Thanks, Nathan

Spool'n Spyder · 05-02-2005, 07:14 PM

Ok, here's another from today......

rpm timing o2v
1820 12 .98
2276 8 1.02
2800 6 1.02
3484 11 .96
4192 12 .98
4908 12 1.00
5540 13 1.00

Correct me if i'm wrong but doesnt it look like i'm still rich, but i'm not getting a whole lot of timing.