LTFTs going negative

[aleco99]

Hi all,

I'm in the process of adjusting my LTFTs. I got some negative values ~-7 and reduces the VE table accordingly. After getting back on the road and logging some more data the LTFTs are getting more and more negative.
What is going on here? Shouldn't the LTFTs get closer to 0?
I read somewhere that the LTFTs can be reset. I havn't done that. Do I need to do that and how do I do it?

Thanks Alex

[macca_779]

Hi all,

I'm in the process of adjusting my LTFTs. I got some negative values ~-7 and reduces the VE table accordingly. After getting back on the road and logging some more data the LTFTs are getting more and more negative.
What is going on here? Shouldn't the LTFTs get closer to 0?
I read somewhere that the LTFTs can be reset. I havn't done that. Do I need to do that and how do I do it?

Thanks Alex

Are you still running the MAF. If you are don't even bother trying to adjust VE as you will be chasing your tail all day long.

[aleco99]

Yes, I still use the MAF. I have my wideband sitting at home but not installed yet.
Anyways, is the result I got normal?

[stigmundfreud]

get that wideband in and dont bother tuning without it. You could monitor the o2 voltages to see if they keep around the switch point but thats fruitless.

Dont alter the ve if using the trims and the maf. You want to get things static so that you are working with the commanded fueling table b0101. Things like dfco, stft and ltft will always skew things if you start by just altering your ve.

Get the ve tuning done in OLSD to get your bens at 1.00 +/- -0.01 then if you wish to use the MAF (like I do) you can go OLMAF. If needed you can then alter the maf scaler (lot of debate on whether or not to do this) then once you have your ben's for your MAF map to 1.00 +/- 0.01

Once you have OLMAF scaled you can move onto CLMAF (where I am at but having strange issues but think that is due to my AD port not being correctly calibrated!)

Test your wideband out of the car by setting a constant low voltage then a constant high voltage. Test each with a multimeter then reset to factory default before installing (in fact do your free air calibration at this point). Then when plugged into the car and all wired to the scanner do the AD calibration to ensure the tool accounts for any signal drop off (this requires two static outputs as in your pre-install test)

If you have a 5 wire MAF you could look at http://forum.efilive.com/showthread.php?t=5459&highlight=b5001 to potentially avoid cutting/splicing a new intake sensor

[SOMhaveit]

I have the opposite thing happening after AutoVE and MAF calibration. My LTFT's are positive. Some as high as 10%. I have adjusted the MAF curve and the VE table concurrently to start getting the LTFT's down.

If I were to simply adjust MAF values, I would loose shape of the parabola I thought you were supposed to maintain. Is that wrong? Should the MAF curve end up with spikes and dips or be a smoothe curve transitioning up?

I will say the car is not running as well trying to get the LTFT's to go slightly negative.