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GM MAF & MAFT Question!

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92EagleAWD

15+ Year Contributor
394
4
Jan 7, 2008
Vero Beach, Florida
Ok, so i have a 3" GM MAF, With a MAFT. Only mods are 2 1/2" turbo back exhaust, and B16g turbo, i dont wanna put anything else on till i figure this out. Im not that familiar with the MAFT yet, ive read through some of the tuning procedures, and im having some problems, My car will idle and run fine, but when i drive it, it will get up to about 3k and start bucking and running like poop, i have a Palm with MMCD for logging. and ive been trying to find out why its doing it, but the only strange thing is that right before it happens the o2 voltage drops to 0 for a second. But i will keep doing this for about 500 rpm and then when it gets closer to 4K the MAF Signal drops to 0hz and stays there and then my FT02 goes right to 100% and it runs great, untill i shift, then it starts all over again. and there is no knock, maybe 2-3 counts sometimes, while this is happening. :banghead:

MAFT setting are Base:2
rest of knobs zero'd out.
 
whats your boost set to? and have you done a boost leak test? sounds to me like fuel cut and your ecu is over compensating for not enough fuel. i could be wrong but if your on stock boost id find someone with a BLT and check for leaks
 
Boost is set at 10psi. last BLT i did was 6 months ago, i found one and fixed it, but i havent had any problems idling or in boost with the stock maf, but ill do another one just to be sure. I also think the sensor may be bad, at idle my FT02 is right @ 100% idling with the stock 1g MAF, and right at 167% @ WOT. But with the MAFT and GM MAF, it bounces around alot, between 90-123% at idle. Same with the o2 voltage Stock 1g MAF: 0.00v at idle GM MAFT: 0.05-0.70 at idle.
 
I cant really wire it wrong, it has a 1g maf plug and the plug for the GM MAF, i checked all the wires, they are all right, and the white wire is spliced into the second to last black wire on my CAS. the purple one is just taped up.
 
highly likely that your front o2 sensor is bad. I know it sounds crazy but trust me I literally just went through this a week ago when I used a maft setup ( which im still working on the tune). Mine would do the same thing run fine til it got warmed up and then the o2 sensor started acting up getting alot of 0 readings then my car would start running bad. To fix it we tuned mine on a 3.5 inch mas when im using a 3 inch but be warned once you replace the sensor your tune will be all out of whack and when I was tuning on a 3.5 inch my trims stayed maxed out making tuning a pain. Best advice before using a maft setup is to fix ALL problems even the small ones because unless your using a maft and safc any little issue could really mess your tune up.:thumb:
 
Boost is set at 10psi. last BLT i did was 6 months ago, i found one and fixed it, but i havent had any problems idling or in boost with the stock maf, but ill do another one just to be sure. I also think the sensor may be bad, at idle my FT02 is right @ 100% idling with the stock 1g MAF, and right at 167% @ WOT. But with the MAFT and GM MAF, it bounces around alot, between 90-123% at idle. Same with the o2 voltage Stock 1g MAF: 0.00v at idle GM MAFT: 0.05-0.70 at idle.

With the stock 1g maf, Did the 02 fluctuate while driving? The O2 sensor should fluctuate between .01-.90, Did you hack the 1g maf? The 02 will stay at .00 with it hacked. The FT02 should not be at 167% at wot. that is full lean. It sounds like you have a vacuum/boost leak, Or you are running out of fuel. The Fto2 should fluctuate just like the 02 sensor, Not exactly the same numbers, But it should be moving constantly. I have never used a MAFT setup, But i know that you have to select the correct injectors, And the knobs are for tuning, You have to add fuel , or remove air, Whichever way it works. Do some more research, Dont blow up your engine dude.
 
If my pos computer didnt stop working i would just upload the log, but i dont know how to on my macbook. With the stock 1g MAF, it does fluctuate like you stated, and no it is not hacked. It runs perfect and everything is as it should be with the stock MAF, but as soon as i put the GM MAF on it goes nuts. I had it set for the stock 450's , Base knob @ 2 and the rest zeroed out, with all 4 switches off.

Ok, so i just looked over the log again, and for some reason my MAFS keeps dropping to 0hz at WOT when it gets past 3k rpm? It doesnt seem to affect anything but im pretty sure it shouldnt be doing that....
 
With the 3"GM MAF switch 3 should be set to on. Try it for starters.
 
For starters, get a wideband. One or 2 clicks of one knob in the wrong direction can cause you to run really rich or really lean. Tuning with a narrowband isn't very accurate. If it was, people wouldn't need to be buying widebands. They can be had for less than $200.

Secondly, it could be that you have a misfire which is causing you to buck. Might need to change your plugs and wires. Just a suggestion.

P.S. Not to mention that your tune may constantly change using this thing. Reason I never even bothered using the fine tuning mode. A wideband helped me GREATLY to keep it dialed in. Another thing you might wanna do is move the translator box to the console for easier adjustments.
 
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