PCM Diagnostics & Tuning - Is this safe?
03-21-2006, 11:59 AM
Is it safe to disable the LTFT's and drag race using only the STFT's? I'm going to E-Town on Saturday and don't have my VE table completely dialed yet. I'm not going to have the time to get it in and re-enable the LTFT's and let the car "learn" the new fueling. Also, I would think that without LTFT's getting in the way you could make changes at the track that would take effect immediately rather than having to drive the 1 hour hundred mile thing.
03-21-2006, 12:19 PM
Are you bringing the laptop and tuners with you? Id keep your LTFTs active while youre driving down there and back, however at the track you can upload a race tune that has them disabled so you dont have to worry about the LTFT's interfering with your WOT fueling. Remember to reset your trims with the scanner otherwise itll hold on to your last known LTFT's.
By the way, we're neighbors, I live in medford.
I've been driving with no longterms for over 1 year, without any issues, and no noticable negative effects.
03-21-2006, 01:36 PM
Thanks for the input guys! GuitsBoy, I think I've seen your car around. Mine's a black Z-28 with a Suncoast SS hood, SS wheels, silver racing stripes, and center mount exhaust (w/ 4 outlets, not the factory two). I always bring the laptop to the track and log every run w/ HPTuners to watch the trims and for KR. They're having the first GM EFI race on Saturday. Have you been to any of them at all? I think I may have talked to you at one.
03-21-2006, 01:51 PM
Slow - Its fine to drive with LTFT's disables once you get your VE in order and the LTFTs are close to 0 anyway. I think fast01 is still in the process of getting to that point.
Fast - Nope, havnt been to english town since well before I had a license. Its a long way to be from home when something breaks. Im always cruising up and down sunrise highway and the SSP. Im at the occasional LIFBA function. Ive got the same exhaust as you, so Ill keep an eye out for ya!
03-21-2006, 01:58 PM
And an added tid bit, the LTFTs do not require a certain ammount of miles to update the cells. You can drive a thousand miles and if you dont drive agressively, you wont update those higher cells.
Once the STFT's pass a threshhold (usually 4) for a certain ammount of time (dependant on engine load) then the computer makes a change to the LTFTs for the cell youre in. If you knwo how to hit all your cells, you could have allthe LTFT's leveled out in under 5 minutes. The easiest way to tune the VE is to simply turn off the LTFT's and log the STFTs in the histogram and past it into the VE. When you get your STFT averages in the histogram even, your LTFTs wont stray too far. Dont forget to reset your fuel trims every time! That is ultra-important!
03-21-2006, 02:14 PM
GuitsBoy, thanks for the info! I'm gonna try and get dialed before Saturday and see what happens. I just added MAC Mids and catted Y along with 3.73's and an Eaton, so I'm hoping for very low 12's to high 11's. Do you know what kind of #'s your car's running?
03-21-2006, 02:20 PM
Do you know what kind of #'s your car's running? As far as times? Nope, havnt had her at the track. As for dyno numbers, those were a bit unflattering since it was an AWD dyno. Lets just say I pulled within 2 HP of a 5# supercharged ls1. :) On the other hand, a 17# s/c 346 had me by 210 HP!