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Long Term Fuel Trims

Predator support for GM gas vehicles

Moderators: mikel, 06MonteSS

Post Mon Mar 18, 2013 9:08 pm

Posts: 55
Location: Roaring Spring, PA
After reading alot on this forum, I was wondering if having my injector slope set at -17 is too much? I followed the instructions about data logging, put over 100 miles on each time before logging. Just want to make sure I'm not going to far.
Shootin for the moon

Post Mon Mar 18, 2013 9:11 pm

Posts: 55
Location: Roaring Spring, PA
By the way, my truck is a 2003 GMC Sierra 2500hd, 6.0 litre. I have dual thrush glasspack exhuast, volant cai, and granitelli motorsports maf sensor.
Shootin for the moon

Post Tue Mar 19, 2013 2:51 am

Posts: 16990
Location: CT

holy crap yeah! going -17% on slope means you are making it 17% richer...

that's a LOT man!

get rid of that crapatelli MAF sensor! aftermarket MAF sensors fool the pcm into thinking the engine is running leaner than it really is, and throws off the fueling... and then when trying to tune the vehicle, it will never be correct trying to get the fueling dialed in, because that MAF is not reporting true/accurate info...

PLUS...

the stock MAF sensor is good for 500/600hp anyway, so there's no reason to change it...

get rid of that Crapatelli MAF sensor, and I bet your fuel trims come back in line, it will idle better, etc....

if you have a cold air intake, make sure everything is tight on that whole setup too so there are no air leaks anywhere....
Image
2014 Camaro SS - 2SS, RS pkg., short-throw shifter, NPP perf. exhaust, BMR strut-tower brace, Cold Air Inductions cold air intake
www.diablewtune.com -- www.diablocustomtune.com -- www.diablocustomtunegm.com

Post Fri Mar 22, 2013 7:23 pm

Posts: 55
Location: Roaring Spring, PA
I switched back to factory maf sensor and got everything settled back in. My ltft's are at 16% still. Should I adjust my slope according to this?
Shootin for the moon

Post Sat Mar 23, 2013 1:22 am

Posts: 16990
Location: CT

that's still high man...

check all the clamps/bolts from the air filter back to the MAF sensor, back to the throttle body, etc... make sure everything is TIGHT so no air leaks anywhere...

do the same for any/all exhaust work... make sure no air leaks anywhere....
Image
2014 Camaro SS - 2SS, RS pkg., short-throw shifter, NPP perf. exhaust, BMR strut-tower brace, Cold Air Inductions cold air intake
www.diablewtune.com -- www.diablocustomtune.com -- www.diablocustomtunegm.com

Post Sat Mar 23, 2013 2:26 pm

Posts: 55
Location: Roaring Spring, PA
Okay, just spent 4 hours going over the exhaust, air intake, and intake manifold making sure I have no leaks. Everything is air tight. I went for a 2 hour drive down the highway and still getting 16% ltft's. Any other ideas? I forgot to mention I also have long tube headers.
Shootin for the moon

Post Sat Mar 23, 2013 8:49 pm

Posts: 16990
Location: CT

headers are all bolted in TIGHT, sealed up with the gaskets, no air leaks around them??? connected to the exhaust tight, no air leaks there???

dunno man, other than that, if you say everything's good, then just roll with it I guess.. still shouldn't be that high though - you're more than half way up to GM's threshold of 25, heh...

but I wouldn't be adjusting the injector slope that much... you need to get a custom tune done so the MAF sensor table (for the stock GM MAF sensor! hehe) can be adjusted instead....
Image
2014 Camaro SS - 2SS, RS pkg., short-throw shifter, NPP perf. exhaust, BMR strut-tower brace, Cold Air Inductions cold air intake
www.diablewtune.com -- www.diablocustomtune.com -- www.diablocustomtunegm.com

Post Wed Sep 06, 2017 3:25 pm

Posts: 2
just wondering what parameters are needed to be logged to adjust the MAF sensor table? similar to how the procedure was written to adjust LTFT's. thanks

Post Wed Sep 06, 2017 5:12 pm

Posts: 16990
Location: CT

you can not adjust the MAF sensor table with the tool.. would need to get a custom tune done..

and predator's are loooong dead and gone.. haven't been supported for 7+ years now..
Image
2014 Camaro SS - 2SS, RS pkg., short-throw shifter, NPP perf. exhaust, BMR strut-tower brace, Cold Air Inductions cold air intake
www.diablewtune.com -- www.diablocustomtune.com -- www.diablocustomtunegm.com


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