I just changed over from 36 lb injectors to 42.5 lb injectors. I changed the injector constant by 16.4% like intense told me to do. I am now running into the whole long term fuel trim running too high. Does anyone on here know how to lower this via hp tuners? I'm still new to the whole hp tuner thing so please be as specific as you can. Thanks, Joe
You need to raise it more if you have posotive LTFT's. I think you should be on a wideband when you do it though. How high are they?
Vaccuum leaks can also cause this, so check for those too.
-Geoff
wouldnt you want to lower it? He probably multiplied the starting ifr table by 1.16 which would tell the computer hes got larger injectors...but it obviously overcompensated and now needs more fuel needs to be put back in...i usually adjust in 5 or 10 % increments till it gets to +/- 2 and then get it dialed in minimally after that.
It doesn't have to be perfect, it just needs to be done in two weeks...
A wise man once said "google it"
shouldn't I be able to drop the ltft down to zero at idle too? I have been messing around with the numbers under fuel control and at idle it keeps on reading 16.4 percent until I start moving in the vehicle (98 GTP). I'm getting the numbers closer to zero when I'm cruising but no luck in changing any idle figures. Thanks again, Joe
Yea, you're right, he has to lower it - I'm dyslexic as hell when it comes to LTFT's and which way to move the injector constant. :POriginally Posted by foff667
To get the LTFT's dialed in comlpetely, you have to play with the slope of the curve too. I usually dial in the WOT end of the curve with a wideband (move the entire curve up or down to get the A/F correct). Then move just the part throttle and idle end around until my fuel trims balance out. It takes a lot of iterations, but you can usually get them pretty close to zero all the way through.
-Geoff
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