GM MAFT WOT Hesitation

[latvianrkey]

I have most of my mods in my profile, but the quick, short list is as follows:

Built 6-bolt
Stock head
255 LPH pump (no AFPR)
680cc injectors
MAFT setup in blow
SAFC in cabin
Datalogger
FMIC
Big 16G

The problem I am having is that when I downshift into 3rd gear and go WOT to accelerate from a cruising speed, my car hesitates until I get boost and then it takes off like normal. I have a narrow band A/F gauge, and I notice that it is reading "lean" (extreme left) while the car is hesitating. When I get some boost built up, it goes "rich" and the car takes off. If I roll onto the throttle, it reads rich (like it should) and it does not hesitate.

I believe I am running version 2.1 MAFT, is this a known problem?
Is a bad GM sensor to blame? (bought it used from a local DSM'er I'm assuming it is good)
If someone could please offer up some help it would be much appreciated.

Thanks,
Andy

 

[latvianrkey]

anybody? any ideas? I've heard that contrary to what my gauge says I may be running extremely rich effectively "choking" the engine. Any thoughts?

 

[playa2334]

Have you had any luck with figuring out this problem??? I have the exact same problem with my maft setup...

Please let us know if, and how, you fix it.

Thanks.

Chris

 

[JessesTalon]

richin it up 5% on your mid'


What are your fuel trims on your logger?

 

[JessesTalon]

narrow bands aren't anything worth even looking at, sorry

Have you done anything recent to make this problem, or did it just occur overnight?
Have you checked your tps voltage to make sure its pretty smoothe ?

You might be having a problem with your FPR getting overran by the walbro.

680s are pretty big to be going off just the maft for tuning. I read their board a bit, and they say max 'safe' with their maft is 660s.

you can tune maf-t for any sized injectors, what do you mean by this...

 

[JessesTalon]

I have most of my mods in my profile, but the quick, short list is as follows:

Built 6-bolt
Stock head
255 LPH pump (no AFPR)
680cc injectors
MAFT setup in blow
SAFC in cabin
Datalogger
FMIC
Big 16G

The problem I am having is that when I downshift into 3rd gear and go WOT to accelerate from a cruising speed, my car hesitates until I get boost and then it takes off like normal. I have a narrow band A/F gauge, and I notice that it is reading "lean" (extreme left) while the car is hesitating. When I get some boost built up, it goes "rich" and the car takes off. If I roll onto the throttle, it reads rich (like it should) and it does not hesitate.

I believe I am running version 2.1 MAFT, is this a known problem?
Is a bad GM sensor to blame? (bought it used from a local DSM'er I'm assuming it is good)
If someone could please offer up some help it would be much appreciated.

Thanks,
Andy

Andy I would buy a AFPR right away... it will help you out. have you had a chance to dyno tune...

What is your base fuel pressure?

also I would zero out your s-afc for now...

 

[latvianrkey]

i do not know what my base FP is, but I know it is probably too high. However, I can not get the car to even idle without richening up the low throttle setting by like 30%. The highs are down 35%. With this I get 0% +or- 5% on my fuel trims, and I get decent tuning at WOT. I also have the POT mod in my car to combat the misfire problem with the swap, and that baro. sensor "trick" I think messes up my low trims, hence the compensation with the AFC. My MAFT also will not even idle without setting it on 550cc size. If I put it on 680 (which i have) It just starves itself......all this with high base FP too.....go figure....

 

[latvianrkey]

also, to even get the car to rev at WOT I have to richen up the 1000, 2000 and 3000 RPM settings to like -5%, and then transition it to -35% by the time I hit 7000 RPMs. Very strange. If i didn't have a Tial BOV I would go back to the stock MAS....

 

[blackGSX2g]

I know this may sound simple, but is your turbo spitting out any oil, or is there any in your IC or IC piping? I had hesitation at WOT when I first installed mine too and it was because I put a new turbo on and it blew all the oil onto the wires of the MAF and it wouldn't run right. Not sure if thats your problem, but I figured I'd put it out there anyways.

 

[latvianrkey]

Actuall, I am burning oil right now because of valve stem seals, but I know for a fact that my IC piping and turbo are good. Good Idea though, I'll check anyway again to be 100% sure.

 

[jfdid]

I wouldn't trust that gauge ALL that much, but keep it in mind, for sure.

Try goin both ways with it...richer first obviously. Then lean it out a bit to see the difference.

Good luck.