VE table and LTFTs

[S2002S]

I have been tweaking the VE table only to bring down the LTFTs. In general, I can see a trend in the LTFTs towards zero, however I'm concerned about the magnitude of change to the VE table. I've been able to reduce the LTFTs by about 4% but in order to do so, the VE table has been change by over 10% in some areas. Is there a maxium limit on reasonable changes to the VE?

What VE table maximums have others ended up with?

Thanks,

Brad

[ZUKI]

1st ,if you have a MAF, make sure it's clean. It also will depend on your particular car. There are times that your VE table may be over 100( I think parts of Keiths VE is). I think the limit is around 140 or so.

[Screamn03]

If you are editing your VE table with the MAF sensor still plugged in it will take alot of VE change for it to show up in the LTFTs. You will most likely end up with too high a VE number than what the motor actually wants.

[S2002S]

The other factor is that I'm at >5000 ft altitude.

I saw a suggestion that the MAF should be unplugged for LTFT tweaking. The help file in V1.5 did not mention this.

Sooo...is the process:
Uplug MAF
Tune LTFTs via VE table
Plug in MAF
Check LTFTs and if they are not correct, then ????

Thanks!

[killer01ws6]

Do you have to turn off any codes while you do this?
Unplug the Maf as you tune the LTFTs with the VE that is.

[S2002S]

1st ,if you have a MAF, make sure it's clean. It also will depend on your particular car. There are times that your VE table may be over 100( I think parts of Keiths VE is). I think the limit is around 140 or so.

Thanks!

The MAF is clean as I use a paper element. My VE table is up to 105 in some areas and I still need to reduce the trims. The MAF is stock and no other tuning parameters have been changed.

[Screamn03]

Here's one way of doing it:
http://www.ls1tech.com/forums/showthread.php?t=219947

Sooo...is the process:
Uplug MAF
Tune LTFTs via VE table
Plug in MAF
Check LTFTs and if they are not correct, then ?

That's pretty much how I did it. I'm using a Granatelli MAF so when I plugged the MAF back in everything shifted about 10% correction for lean (+10 LTFTs) so I just multiplied my MAF by 10% and it brought them back in line. WS6snake-eater's posted method will work better and is more accurate but I haven't done it yet because I will be installing headers and removing the cats soon. I just wanted to get everything in the ballpark. I just ignored the SES light while I was doing this but you can set the p0102 code to "SES Enable On Error Code #2-No MIL reported" if it bugs you. Do not disable it as the computer will then think the MAF is ok and the car won't run (remember you have it unplugged, no flow is registered). Another thing the computer will do when you unplugg the Maf sensor is run on the low octange spark table. You can just copy the high octane table into the low ocatane table while you have the MAF disconnected and return it back to normal once you're done.

[S2002S]

Forgive the dumb questions, but isn't SD tuning for MAFless setups? Also, doesn't the Granatelli MAF provide built in scaling on the MAF outputs?

I've seen recommendations to leave the MAF scaling alone, unless you modify the MAF in some way.

Can I just unplug the MAF and ignore the SES light, and later clear the codes?

Thx!

[AnotherUser]

Forgive the dumb questions, but isn't SD tuning for MAFless setups? Also, doesn't the Granatelli MAF provide built in scaling on the MAF outputs?

I've seen recommendations to leave the MAF scaling alone, unless you modify the MAF in some way.

Can I just unplug the MAF and ignore the SES light, and later clear the codes?

Thx!

No, SD tuning is needed because your PCM uses SD mixed with MAF readings up to about 4k rpms. The PCM also uses the SD (VE) to sanity check the MAF readings. Additionally, aftermarket MAFs are often wrong. Tuning your MAF is not as easy as porting it out and tossing in a resistor. But somehow Granatelli thinks it is, and has a bunch of people conned into spending their money on their MAF units. You can unplug the MAF and ignore the SES light (as long as you don't have other problems), but your VE table needs to be within the range where your fuel trims can correct your fueling.

[S2002S]

No, SD tuning is needed because your PCM uses SD mixed with MAF readings up to about 4k rpms. The PCM also uses the SD (VE) to sanity check the MAF readings. Additionally, aftermarket MAFs are often wrong. Tuning your MAF is not as easy as porting it out and tossing in a resistor. But somehow Granatelli thinks it is, and has a bunch of people conned into spending their money on their MAF units. You can unplug the MAF and ignore the SES light (as long as you don't have other problems), but your VE table needs to be within the range where your fuel trims can correct your fueling.

Sooo....
Unplug MAF.
Copy high octane timing table to low octane timing table.
Modify VE to acheive LTFT.
Reconnect MAF and restore low octane table.
Recheck LTFTs and if they are wrong then what? Continue VE table tweaking? Tweak the MAF tables (I have a stock MAF)?

Thanks again for the good advice!

Brad

[luv2spd]

Once the ltft's are in line with the maf disconnected, plug the maf back in and multiply the maf table to get the trims back to slightly negative. Keep the ifr stock unless you changed something with the fueling (injectors).

[xssive]

Can this method be used on an a4 car?

[Screamn03]

Forgive the dumb questions, but isn't SD tuning for MAFless setups? Also, doesn't the Granatelli MAF provide built in scaling on the MAF outputs?

A proper VE table is a must either way, maf or mafless, but it's more important mafless because that's all you got for airflow. It works like anotheruser explained.
Yes Granatelli does some stupid *%&* with their MAFs and it's a tuning nightmare but I've managed to get it somewhat figured out and the car has picked up power without suffering drivability. What I like about it is the smooth open design and that I got it real cheap doesn't hurt either. I wouldn't go and buy one new, ever.

I've seen recommendations to leave the MAF scaling alone, unless you modify the MAF in some way.

This is true but if you modify something that affects the way the air flows across the MAF then it will also be slightly inaccurate. Different lids and induction parts can throw the MAF off slightly. So scaling it within a reasonable range is ok.

Can I just unplug the MAF and ignore the SES light, and later clear the codes?

Yes, and don't forget about the the spark table issue.

[killer01ws6]

I also think adding Ported TBs and such mess with the Maf.

I have told you guys forever that My LTFTS would not go Neg......


Well some of you may remember I have posted about my car having a slight stumble and then my MAF failed.......

well I ordered a new one yesterday and for kicks and giggles I unpluged the Maf on the way to work today BOOM!!!

-6 to -16 across the board.......

she was still in heavy learn mode (stfts in the 20's) but I am going to drive her this way, tweek the VE and when the new Maf gets here if it does not read the same tweek the Maf table.

for me it may have been a dying maf for sometime, but we will see.

[checkmate]

With 1.5 can you disable LTFT and just go off of STFT???

This has been a very helpful thread.

[Dirk_Diggler]

You dont want to diable LTFT's until you get your trims greater than -10

[S2002S]

Thanks for all of the excellent advice. I'm waiting for my EIO package exchange to try this out.

Brad

[TT_Vert]

You dont want to diable LTFT's until you get your trims greater than -10

why? Mine were +6 to +10 when i first disabled Ltrims.

Dave