God Forgives I Dont

Are the tuning guides incorrect or do we just not have the ability to see a stored LTFT averaged learned table?

Meaning that if the PCM truly holds a LTFT average table to use the next time the car starts up, then why can't we just view the table to see what’s there?

As opposed to the current method, where we drive around and just record current LTFT and then average out what we recorded.

If the PCM isn't storing a LTFT table from the last time the car was driven then someone really needs to change all the Tuning Guides to say "Drive your car for 100 Miles (or until LTFT get stable) and then start logging and at no time during that drive should you turn off your car or you have to start back over again as the PCM will have to relearn an average from driving it around".

To me when I read all of the various guides they say to drive the car 100 miles so the PCM can relearn LTFT then log, but the way it's worded it sounds like you could just drive the car like normal and after a couple of days make a log and it would be averaged out by then which wouldn't be correct as it would be solely dependant on how long you drove with out turning the car off for it to stabilize before you start logging data (with out turning off the car).

Also there would be no point in resetting the LTFT in between runs or after flashing the PCM because the PCM isn't holding a LTFT table when the key is turned off.

If it does hold a table why wouldn't HPTuners give us an option to view it as it would make life so much easier to get VE tables perfect and wouldn't take as much logging sense the PCM is automatically storing the log for us.

Someone please correct me if I'm totally wrong here!

JNorris

iTrader: (4)

You can with EFILive. Below is the text of the result. When you look at it in EFILive it is in a nice graphical format.

Cell# MAP/RPM boundaries Bank-1 Bank-2
0 MAP 0.00..10.9 inHg/RPM 0..900 -0.98% 0.00%
1 MAP 0.00..10.9 inHg/RPM 900..1400 0.00% -1.95%
2 MAP 0.00..10.9 inHg/RPM 1400..2200 -2.93% 0.98%
3 MAP 0.00..10.9 inHg/RPM 2200+ -1.95% -1.95%
4 MAP 10.9..16.8 inHg/RPM 0..900 -1.95% -0.98%
5 MAP 10.9..16.8 inHg/RPM 900..1400 -1.95% 0.00%
6 MAP 10.9..16.8 inHg/RPM 1400..2200 -2.93% 3.91%
7 MAP 10.9..16.8 inHg/RPM 2200+ -0.98% 3.91%
8 MAP 16.8..22.7 inHg/RPM 0..900 3.91% 0.00%
9 MAP 16.8..22.7 inHg/RPM 900..1400 0.00% 4.88%
10 MAP 16.8..22.7 inHg/RPM 1400..2200 2.93% 5.86%
11 MAP 16.8..22.7 inHg/RPM 2200+ 1.95% 0.98%
12 MAP 22.7+ inHg/RPM 0..900 0.98% 0.00%
13 MAP 22.7+ inHg/RPM 900..1400 -0.98% 0.00%
14 MAP 22.7+ inHg/RPM 1400..2200 0.00% 0.00%
15 MAP 22.7+ inHg/RPM 2200+ 0.00% -0.98%
16 P/N: A/C On 0.00% 0.00%
17 P/N: A/C Off 0.00% 2.93%
18 In gear: A/C On -0.98% 0.00%
19 In gear: A/C Off 0.00% 1.95%
20 Cold idle 0.00% 0.00%
21 Deceleration -0.98% 4.88%
22 WOT 1.95% -0.98%

God Forgives I Dont

[QUOTE=JNorris]You can with EFILive. Below is the text of the result. When you look at it in EFILive it is in a nice graphical format.


So you can pull this data with out having to drive around and record a log to get averages? In other words I'm asking if this is a stored table in the PCM verses one that is just temporary while the car is actually running.

Thanks for responding I've been wondering about this for some time.

RedHardSupra

iTrader: (1)

umm...anyone knows how to do it in HPT?

gameover

we support this at the current time, it is on the list for a future release. The thing is, it works for the first time but then you go and change something and you'll want to reset the fuel trims and go driving anyway. Also you can only report the fuel trims on a per cell basis, so depending on your tune you may have issues within cells that are causing problems.

IMHO, zero and disable LTFT's and tuning with the STFT's, or use a WBO2. Much faster.

Chris...

JNorris

iTrader: (4)

You will still have to drive around so the PCM can gather the values. These are the average per fuel trim cell that the PCM uses.

John

Fetumpsh

This is what the screen looks like -

YellowToy/A

iTrader: (1)

Ok let me ask this question. As I watch my logs of STFT and LTFT it looks like the STFT update in MS and the LTFT update in Seconds(not many). Why do people say to drive a long time. I look at he data from a 50 mile trip and the trims do not change as long as the MAF air flow is the same.

Long story short. GAMEOVER how long does it take to update LTFT and STFT?

horist

LTFT = Long Term Fuel Trims
STFT = Short Term Fuel Trims

LTFTs update off of the STFTs, they're an average basically

I usually leave the LTFTs disabled, and then view the average of the STFTs, then update my VE table off that

mike s.

iTrader: (2)

how do you view the averge of the stft's?

horist

in HPT , in the histogram right click, and change it to average... it'll then print the average value in each VE vs RPM cell

gameover

The STFT move very rapidly with the O2 sensor readings to move the fuel to a point where the O2 sensor is oscillating about the rich/lean switchpoint. Think of the STFT as a "fast" learn.

The goal of the LTFT is to make the STFT = 0. It is a longer term average, it updates in the order of seconds. It usually takes less than 20secs for the LTFT to learn in each cell. Think of the LTFT as a "slow" learn.

The sum of the LTFT and STFT at any time is the actual closed loop fuel correction applied to the fueling calcs.

Peopl say to drive 50 miles of highly varied driving to get a good indication of the LTFT's becuase it is very difficult to hit all the RPM/Load points for a sustained period in a quick trip around the block. If you use STFT's it is much faster. However, you must make sure LTFT's are disabled and reset to 0.

The STFT is not stored in NVRAM in the PCM nor is it cell based. It is a constantly varying number and when you enter openloop conditions (eg. WOT) it sets to 0.

Chris...

God Forgives I Dont

Excellent Info do you think that feature will be in 2.0?

Good point using the short term only when you’re getting close to dialed in.

I'll be doing that this weekend and then go back to work on my MAF, it's not an easy task but I'll get it there eventually.

I need to bust out the $$$ to get the upgrade cable so I can hook up my WB. But cash always seems tight these days.....

Thanks again for the info