Ltft ?
Thread Starter
On The Tree
Joined: Nov 2007
Posts: 110
Likes: 0
Ltft ? Ok, here is something that is bothering me. I was a Ford tech(please don't give me hell) for years and have many years of racing. BUT, this is my first
LS1 car. When I read about LTFT everyone says you have to drive the car for 30-45 min, to get them correct. I have not tested this with my car yet, but on all the Fords I have worked on over they years, they change fast, and often. Lets say I created a vacuum leak, it would charge LTFT in less then a minute or two. If a car has a small leak it may move LTFT +5 to+9 but at idle but at cruise would be back to + or -3. Ford said + or - 3 was normal. Are GM LS1's slower to change? I am going to do some research on mine, but was just reading some tuning info, and got me interested. Thanks
LS1 car. When I read about LTFT everyone says you have to drive the car for 30-45 min, to get them correct. I have not tested this with my car yet, but on all the Fords I have worked on over they years, they change fast, and often. Lets say I created a vacuum leak, it would charge LTFT in less then a minute or two. If a car has a small leak it may move LTFT +5 to+9 but at idle but at cruise would be back to + or -3. Ford said + or - 3 was normal. Are GM LS1's slower to change? I am going to do some research on mine, but was just reading some tuning info, and got me interested. Thanks
Last edited by quik406; Mar 30, 2008 at 11:42 AM.
after you re-flash the pcm it takes a little while for the pcm to re-learn some ltft's. i've noticed it doesnt seem to take 30 mins more like 10-15mins at most with varying the throttle/mph in my experiance.30-40 mins is a bit too long imo,
quik406: Our LS1 cars change just as fast as the Fords. It takes only about 1 minute while being in the same Fuel Trim Cell (FTC) for the LTFTs to be updated. However, we have 16 FTCs while cruising around and several other special purpose FTCs, like idle (warm & cold) and WOT. I think that whats important is for you to know is a specific driving routine that visits your most likely FTCs. For my 402 on a short driving cycle, I am in FTC 7, 11, 6, 10, 15 the most. Warm idle is 19, cold idle is 20, and WOT is 22.... I run Autotap while I drive this routine and watch the FTC and LTFTs as I drive (w/o taking my eyes off the road too long). When I think that most of the updating is done, I then start a data logging session and get the PCM into these FTCs so that I can continue my tuning efforts on my new 402 LS2 transplant. Hope this helps.
