GM MAF tuning problems---?

[jfdid]

Ok guys, here goes (fairly long, but please read!).

1g talon, 16g, new 680's, GM MAF, MAFT V2.xx, Walbro 190(rewired), laptop w/TMO.

So I installed these injectors, "65 lb" injectors, basically working out to 680's or so. Got the GM MAF off the 'net. Turns out one of the wires on the MAF was broken, so I soldered it back on. Now this is the scenario:

I haven't found the right place to set my BASE. I tried the 680 setting, but the idle was garbage, and I was knocking all to good heaven.

Played with a bunch of stuff, WOT, etc for an hour or so.

Bottom line from what I can tell:
a) my 02 sensor is garbage, but nevermind that now

I'm knocking at WOT in the mid-high rpms: 4000-6000 or so. About 20 on the knock count. So what do I do? Richen the settings up via the WOT setting. Now, depending on the BASE setting, this either doesn't richen enough, and I'm still knocking or even worse---------FUEL CUT????

I say Fuel cut because I don't know what else it could be. It's weird...currently it's happening at 4600RPM or so. My boost is set to 11PSI? I didn't think a 16G could create fuel cut at a mere 11psi? Anyways, so what happens is it will climb up to about 4600 RPM and then it will studder for a SPLIT second(only noticeable to the keen senses of a driver, not to the passenger, that's how short the studder is) then it will totally just go bam and send your head into the steering wheel.
Now I'm not an expert on fuel cut by any means, but it is a 1990 talon with a stock ECU. The logger says the Air Flow Hz doesn't even reach 1600hz, so could it still be fuel cut?

Any direction as to what could be happening would be greatly appreciated!
My only thought(other than fuel cut) is the 190 not producing enough fuel? But can that really be? 11PSI on a 16G maxxing out a 190lph pump? Fuel filter?

Thanks again!

 

[Talonman]

you need to click this link here: http://www.fullthrottletech.com/forums/forumdisplay.php?f=6 and look in teh dsm maft tuning forum. I dont have a maft but reading thru the setup thread you must tune the 4 base knobs correctly before even attempting the wot settings. The thread is MAFT Version 2.0+ Tuning Guide.

 

[Nos~4G63]

Are you able to log airflow? My car had similiar symptoms when I had a bad MAF.

 

[jfdid]

An update: The car now does it at around 5000rpm today. It was warmer today by quite a bit...would that have a difference, or is it something fuel(pump/lines) related.

I am also thinking the MAF may be faulty. Anyone else with any ideas?


Thanks Talonman, I've checked out that site....not much helping me. I'll try tuning everything else first, but in theory, you shouldn't have to...as long as the BASE is set up.

Thanks guys, keep the ideas coming.

 

[latvianrkey]

mine is doing the same thing. THe stutter you talk about is also happening to me, and the BAM like getting shot out of a cannon is also there. I look at my a/f gauge, and it goes dead lean then when boost picks up it goes full rich and takes off like a bat outta hell. Im assuming that the MAP sensor is taking over at WOT and dumping fuel. If you find it to be a bad GM MAF sensor, please let us all know.....Im still trying to tune it with no luck.

 

[jfdid]

An update on this:

I got a new O2 sensor, and it goes full rich(.99v) when it bucks....SO

I leaned it out and the car pulls really hard. I was just putting too much fuel in it.

The downside: My knock sensor shows hella-knock most of the time, but I'm thinking it's phantom knock, so I'm not too worried about it, except it's ruining my timing...DAMN

 

[FASTSPOOLINGST]

I have 680cc injectors and to get my trims in a good range, i had to set my base to the "580cc" setting with Aux 1. My trims are all 98-101% in the low mid and high.
Try it out, richer is better anyways to get a idea, if your trims are really really rich you can always lean it out bit by bit. I checked on full throttle and it seems everyone else is kinda in the same boat, their injectors don't match up to their base in the instructions. Some guys are 50cc's off, some 100cc's, it all depends i guess. Well that's my .02 cents dude, I hope it will help you out.