99whitews6

iTrader: (2)

If you do, what is the CORRECT way to shut off the LTFT's so they dont learn anymore?

Also, when in the tuning stage do you just reset fuel trims and adjust VE table after every 20 minute drive since the STFT's update continuously?

When you were done tuning the STFT did you turn back on the ltft's? Were they the same?

luv2spd

iTrader: (1)

I really haven't had much time to mess with it, but I think you want to turn off the ltfts in the actual tune. Yeah, it doesn't take much driving since they update so fast.

99whitews6

iTrader: (2)

?????

horist

The LTFTs need to be turned off in the PCM to use STFTs for SD tuning.

In HP Tuners , under Engine -> Fuel Control -> Open & Closed Loop

Long Term Fuel Trim Enable, set to off

LTFTs will no longer be used and only STFTs will be used

99whitews6

iTrader: (2)

Can I just tune with the STFT's and not using speed density? Just normal maf tuning.

Silverhawk_02TA

What horist said.

Make sure your LTFT's are within +/- 10 before turning them off and using your STFT's to tune. This is the method I use, and lemme tell ya, it's a hell of a lot quicker and less of a headache.

When using STFT's there is no trim resetting to be done, as STFT's are not "learned". They are a second by second fueling adjustment that the PCM uses based on what the O2's are showing. I will typically log for 10 minutes, then adjust the VE table, then log another 10, etc. Using this method, I was able to get my VE table adjusted so that all my STFT's average between +/- 3 in less than an hour.

When you're done, just re-enable your LTFT's. Once they learn out, they should all be very close to 0.

Silverhawk_02TA

Anytime you are using trims to adjust your VE table, you want to do it with the maf unplugged or disabled. Otherwise your trims are being affected by what the maf is reading, and they will never be a direct representation of the correctness of the VE table. After your trims are brought in line from adjusting your VE table is when you want to re-enable the maf, and then scale the maf table to keep your trims within spec.

405HP_Z06

iTrader: (11)

Do the LTFT's default back to 'on' when you turn off the car or do they stay off if you do this? It looks like they turn back on when I cycle the ignition key.

horist

if you turn them off w/the scanner , they'll turn back on by default... but if you turn them off in the editor, (turn off, flash PCM) they'll stay off until you reflash with another tune that has them turned back on

I haven't tuned my TA w/this in a while (damn winter, and now she's sans a transmission) but when I was doing it, they would stay off indefinetly until I turned them back on (using the editor) ...

Silverhawk_02TA

Again, what horist said.

I've been running with the LTFT's disabled for weeks now. I suppose I'll turn them back on again someday, but right now I'm having too much fun playing with my VE table.

DAPSUPRSLO

iTrader: (14)

Is it a bad idea to tune SD with no MAF from ltfts when starting with a completely new top end (h/c, headers, exhaust)? Should you use the stfts? With ls1 edit how would one go about this? I have EFI Live but no bi directional controls. Thanks.

Silverhawk_02TA

Always start with LTFT's first. This will give your PCM a greater range of adaptability as far as modifying the fueling if your VE table is way off. Think of it as an added safety margin. Switch to STFT's when your LTFT's are within the +/- 10 range.

Not sure how you would go about it with LS1 Edit, since I've never used it.

99whitews6

iTrader: (2)

alright, i am currently tuning my LTFTs using VE(maf is still connected). I dont have time to go SD till the weekend because it seems like there are multiple things to turn off and adjust to go speed density.

After cam install I logged LTFTs(averaged) and the histogram showed values between 0-7. I then increased the primary and secondary VE accordingly and reset the fuel trims. I have driven about 90 miles since and I just got back from a 30 minute log. Now the histogram shows values from 7-10 in those same regions.

Shouldnt the values move closer to zero since i increased the VE table?

Also, the STFTs from this same log are now closer to zero than before (all values are now -2 to 3 with a lot of 0's). Why did the STFT values go closer to zero and the LTFTs go farther away from zero?

Is the car ok to drive until the weekend when I have time to work on it? (i have no KR).

Silverhawk_02TA

Number one, you can't use your trims to accurately correct your VE table without disconnecting your maf. With the maf plugged in, the PCM uses the airmass reading it provides to set fueling. All the VE table is used for in this situation are throttle transitions, and as a sort of sanity check for the maf. Only when the maf is disconnected does it fall back to the VE table to derive the calculated airmass value. Your method is correct, but it will only work in SD.

Second, STFT's close to 0 are just showing that your LTFT's have been learned. LTFT's and STFT's work like this: Say the value of one cell in your VE table is 70. Now, let's assume that the "actual" value of this cell should be 85. When the PCM falls into this cell when you are driving around, your 02's will report a lean condition, causing your STFT's to go to around +15. Now, when the STFT's change the fueling by 10% or more for longer than 10 seconds, the LTFT's begin to compensate by swinging towards +15. How quickly this happens depends on how long the engine operation falls in the cell in question. If it's a cruise cell, then the LTFT's will reach +15 very quickly, at which time the STFT's will drop back to around 0, since the LTFT's have adjusted fueling to compensate. If you happen to log it before it is fully learned, you might see an LTFT of +10, with an STFT of +5. Of course, the math isn't always nice and clean like this, but you get the picture. This is what makes tuning with STFT's alone so much easier; you don't have to wait for them to be learned.

Your car is safe to drive around. It's just showing that the "actual" fueling is 7-10% off from the "mapped" fueling. The PCM has a pretty big range of adaptability with both the LTFT's and STFT's.

And there's actually not much to going SD. Just unplug your maf. You can disable the SES light for the codes it's going to throw if you don't want to see it on. Then just copy your High Octane spark table to the Low Octane one, since the PCM reverts to it if the maf fails. Otherwise, just log and adjust your VE table like you've been doing.

DAPSUPRSLO

iTrader: (14)

Great post man. I guess I'll have my work cut out for me considering I will be using ls1 edit. What's the fun without a challenge though, ha ha.

ty_ty13

iTrader: (42)

can we sticky this?
because ill need it later

99whitews6

iTrader: (2)

WOHOOO

So I unplugged my MAF during my lunch break today and went SD to tune. Before I unplugged the MAF my LTFT's were about 7-11. After I unplugged I watched the STFT's and as soon as i started it up all the values went around 20 ish. I drove, adjusted, drove, adjusted, on and on for about 45 minutes and now all the STFT's are -3 to 2. Car likes me noW!!!!!

So whats my next step?

Silverhawk_02TA

That depends on whether or not you want to plug your maf back in.

First off, re-enable your LTFT's. It wouldn't be a bad idea to log and check them after a week or so just to see where they end up. Shouldn't be any surprises, but it never hurts to double check.

If you plug your maf back in, it's going to queer all your LTFT's again. Then you get to scale the maf table until they come back into line. Conversely, you could remove it all together and turn it into a flower pot or something. Whatever you decide, after that it's time to take it to the dyno and do some WOT tuning!

99whitews6

iTrader: (2)

thanks,

Wideband is being ordered today so no need for a dyno run!

Assassin

iTrader: (3)

"flower pot" .......... LMAO I frikken love it.... hahaha..... I think I will give my girlfriend a nice automotive flower pot for her birthday..... lol