MAFT Gen 2 - Anyone?

[David_J]

What are your plug gaps? Stuttering (not knock) at high boost or high rpm is usually too rich or blow out. Since your fuel curve is fine for 15psi, you can discount the too rich part.

[twinturbvr4]

I havent checked the plugs in a while.. I believe i gapped them for almost the lowest tolerance a while back... I think I have my coppers in.. so they could probably use a swap.. I noticed also this morning at probably 90% WOT around maybe 4500 rpm I was running around 11 AFR.. if I went 100% WOT it went to 12.2 SOLID didnt budge until I let off.. I think I have my AFR tracking set somewhere around there.. possibly raise it up? I was thinking ~12 isnt too bad for WOT with that kind of boost.

thanks for the info.. ill get some logs and see what kind of knock I have.. when I was first making some boost adjustments (on my mbc) I had it up around like 18psi.. (-19 mainscale still) and my exhaust farted a lil (too much boost farting..lol).. so i backed it down and it stopped..

[twinturbvr4]

Hey guys, I'm having some major trouble running at 16+psi.. anytime I go over 15.. the car starts sputtering and stuff.. seems like it has moved from doing that at 17-18 psi, down to 16psi.. weird. I have my AFR tracking across the board set to ~ 14.7 and at WOT it runs pretty good around 12.. -19 on the mainscale... I "believe" I zero'd all the Hi/Mid/Low settings.. I just installed my new fuel pump last week, maybe not getting enough fuel? I pulled a 2nd and 3rd gear log a few days ago, but my palm freaked out.. I had like 81.2% fuel across the board for both pulls... that seemed a bit weird, especially that hi/mid/low were all the same... and that it seemed a bit low.. any suggestions?

[Drweldin]

Originally Posted by twinturbvr4

Hey guys, I'm having some major trouble running at 16+psi.. anytime I go over 15.. the car starts sputtering and stuff.. seems like it has moved from doing that at 17-18 psi, down to 16psi.. weird. I have my AFR tracking across the board set to ~ 14.7 and at WOT it runs pretty good around 12.. -19 on the mainscale... I "believe" I zero'd all the Hi/Mid/Low settings.. I just installed my new fuel pump last week, maybe not getting enough fuel? I pulled a 2nd and 3rd gear log a few days ago, but my palm freaked out.. I had like 81.2% fuel across the board for both pulls... that seemed a bit weird, especially that hi/mid/low were all the same... and that it seemed a bit low.. any suggestions?

Yes - set the AF tracking to something richer than stoich! More in the 11.5 range....that may help. I say may becuse the Max Lean function would have prevented whats happening (I would think). Also check your fuel pressure.

[TurboBob]

trims that read 81% are not unusual, and are not a problem. I set my car up that way intentionally. Watch the O2 trim while driving (part throttle) to make sure its not bottoming out (32), try to keep it in the 80-90 range.

I agree that 11.5 is the proper AFR to start with at WOT.

I missed what injectors and turbos you are running.....?

Post a log, that will help a lot

Bob

[twinturbvr4]

Thanks as always for the help guys!

I originally had my AFR trackingn setup down around 11.5 too.. but was gettin way rich at like 75%-100% WOT.. like 10.5 and lower!

Im running 16t turbos and 450 injectors with a new walbro pump.. (not hotwired yet) (I will be going 550s possibly next month)

I'm also in blow through now with a 3.5" GM MAF (yes I remembered to change from 3.0 to 3.5 in the settings ) lol

Unfortunately my Palm took a poop on me like right after I pulled the log and didnt save it.. the only thing I can remember is the 81.2 fuel trims and I had a couple knocks, like 3 at one point and 6 at another (neither were at redline) I have to actually re-download the software BACK on to the palm.. all this and I'm hitting opening day at the track on saturday! ahhh!! lol

If all my hi/mid/lows are in fact 0'd out should I just try to make the AFR tracking adjustment and keep it at -19 and try from there? or should I reset and start over? I don't think much else has been changed..

CORRECTION: After going out and setting the AFR to 11.5 across the board, I checked my low/mid/high fuel settings.. I didn't realize not everything was 0'd out... I had +2.0% pretty much across the board in the LOW.. and +5.0% across most of the low to mid rpm ranges in the MID, and mostly 0 in HIGH except for a high rpm -10.0% setting.

Is there anything in the AFR tracking I should also set.. Gain, Aux %, etc? I have not adjusted anything other than the RPM range desired AFRs..

[twinturbvr4]

Alright.. I duno what the hell happened.. did all that.. was boosting fine all the way to 18psi at -22 on the mainscale and 11.5 AFR across the board (running about 12 AFR at WOT) Then as I was boosting up a hill in 2nd.. hit full boost, started sputtering and actually bucking, after that as I would approach 15psi it kept doing this and will not boost past 15psi anymore, MBC still set at 18psi..

NEVERMIND: the trans had no effect on this, just conicidentally happened at the same time. Still having problems with the trans in working condition. Going to switch the plugs, I believe I still have coppers in, so they need to be changed.

BINGO: Plugs definitely saw the end of their life.. heavy burning, and gapped way out. almost .40... got new NGK coppers .30.. working very nice now

[Drweldin]

Figured I'd post this question here 1st (TurboBob?)
My car still runs very good, but one thing has me confused:
If I am sitting still, and hold throttle at 2000 rpms (or anywhere close)
I go lean, and get mild popping, etc (17-19 afr)....is this normal?
Car drives great...just this no load manual "high idle" is lean....

[TurboBob]

it sounds like the ecu is entering lean coast-down mode.

what are your trims (all of them) doing when this happens?

Bob

[Drweldin]

Originally Posted by TurboBob

it sounds like the ecu is entering lean coast-down mode.

what are your trims (all of them) doing when this happens?

Bob

I'll have to post back on that one.......