Quick Dyno - LTFT Question
Thread Starter
Launching!
Joined: Aug 2002
Posts: 231
Likes: 0
From: Ontario, Canada
Quick Dyno - LTFT Question Hey guys.
I've got my VE tables in good shape down low. All showing pretty darn close to -5 to 0. Problem seems to be the few 0's I've got lingering around are actually slightly positive on me on the drivers bank.
On the night I dialed in my tune the car ran hard and great. Trims 0'd at WOT and I saw 12.8:1 AFR. Wicked. This morning (a few days later) the car hit me with +4 trims at WOT. I was pissed needless to say.
I've got a dyno booked tonight. I've got a wideband. If I turn off LTFT for the dyno pulls will that 0 them for me at WOT so I can just use PE to get myself on track? The car has a good MAF cal in it and the VE was tuned using trims instead of a wideband (don't have an EIO setup yet).
Any/all responses are awesome! I just want a quick way to get some unmolested numbers out of the car tonight. I'll fix the tune the "right" way afterwards and massage the VE more so it stops doing this to me.
I've got my VE tables in good shape down low. All showing pretty darn close to -5 to 0. Problem seems to be the few 0's I've got lingering around are actually slightly positive on me on the drivers bank.
On the night I dialed in my tune the car ran hard and great. Trims 0'd at WOT and I saw 12.8:1 AFR. Wicked. This morning (a few days later) the car hit me with +4 trims at WOT. I was pissed needless to say.
I've got a dyno booked tonight. I've got a wideband. If I turn off LTFT for the dyno pulls will that 0 them for me at WOT so I can just use PE to get myself on track? The car has a good MAF cal in it and the VE was tuned using trims instead of a wideband (don't have an EIO setup yet).
Any/all responses are awesome! I just want a quick way to get some unmolested numbers out of the car tonight. I'll fix the tune the "right" way afterwards and massage the VE more so it stops doing this to me.
3~4% swings are slightly above average, but can still be considered normal. Ideally, most of the tune is in the MAF if you're still using it. Only low airflow situations refer more to the VE table. Even then, the MAF will have a decent influence. Figure out where you're seeing the positive fuel trims in your MAF table. Then add in another .25% to that area of the table. In other words, say you notice your STFT's start leaning more to the positive side inbetween 3,000 and 4,000 Hz. Multiply that part of your MAF table by 1.0025 and reload the tune into the car. I dialed in my MAF table by making decent changes at first and then making minimal adjustments (1/8 of a %) as needed. Now, the only time I see positive fuel trims is during idle when IAT's are in the 130's. The lowest I see is -4.8% on the passenger side usually.
BTW, if the dyno has a wideband, ask them to hook it up too. Last time I was on one, there was a whole AFR point difference between my LC1 and the shops wideband. Now, I need to find a 3rd one to see who's was right/wrong.
BTW, if the dyno has a wideband, ask them to hook it up too. Last time I was on one, there was a whole AFR point difference between my LC1 and the shops wideband. Now, I need to find a 3rd one to see who's was right/wrong.
Thread Starter
Launching!
Joined: Aug 2002
Posts: 231
Likes: 0
From: Ontario, Canada
Awesome info buddy. Thanks. I'll load up my previous "good" tune and just play with the MAF. The car ran like a champion at WOT and mid/part throttle so I know it's a good tune. The upper VE could be closer with a wideband but it was pretty okay.
I was commanding 12.2:1 and I was seeing 12.8:1. Pretty close. Better when I do an AFR% I know.
The dyno we are going to tonight does the same thing! Buddy of mine had a full point different (.85 or so) between his and the dyno's. Go figure eh? I'll see what I come up with.
I'll leave LTFT enable alone and get that MAF where I need it. Gotta load the MAF tune back in and go through Case learn again. Joy...
I was commanding 12.2:1 and I was seeing 12.8:1. Pretty close. Better when I do an AFR% I know.
The dyno we are going to tonight does the same thing! Buddy of mine had a full point different (.85 or so) between his and the dyno's. Go figure eh? I'll see what I come up with.
I'll leave LTFT enable alone and get that MAF where I need it. Gotta load the MAF tune back in and go through Case learn again. Joy...
