SS125

iTrader: (1)

I have studied all the information on the C5 Forum about the LTFT's and reasonably understand it. I have a couple of questions. In the article on C5 Forum, he states there are fuel cells 1-22, with 22 being wot, 21 being deceleration, and 20 is idle. When you get the data into the data table, do you eliminate all the lines with any of these in the fuel cell column? And finally, I ran atap today and I get a 0 in the fuel cell column, lot's of 0's. What are these and do you remove these also?

Team ZR-1

Too bad everyone uses that webpage and excel file, esp if they are just begining for it is not correct.

There are 0-22 cells, cells 17/18 are A/C idle, 19/20 are A/C not on ( cold/hot), 21 is longer lift time off g-pedal, 0 is used with auto trannies from what I have seen,
cells 1-5 are lower MAF Freq. shorter lifts on g-pdeal and cells 15 and 22 for high load conditions.
Cell 6 I see used when cruise is on at highway speeds/70 MPH

That excel sheet you speak of averages all cells of 1-19 which skews the "ON g-pedal" / load cells so that LTFT averages are not totally correct.

It also has WOT being when only greater then 99% of TPS when it is more like greater then 80%.

It also only considers knock a issue when greater then 3 degrees, yet that could be enough to drop the timing from hi to low octane timing tables.

It also does not consider, injector pulse width/duty cycles, delivered torque and misfires,
which effect performance and tuning.

SS125

iTrader: (1)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Team ZR-1:
<strong>Too bad everyone uses that webpage and excel file, esp if they are just begining for it is not correct.

There are 0-22 cells, cells 17/18 are A/C idle, 19/20 are A/C not on ( cold/hot), 21 is longer lift time off g-pedal, 0 is used with auto trannies from what I have seen,
cells 1-5 are lower MAF Freq. shorter lifts on g-pdeal and cells 15 and 22 for high load conditions.
Cell 6 I see used when cruise is on at highway speeds/70 MPH

That excel sheet you speak of averages all cells of 1-19 which skews the "ON g-pedal" / load cells so that LTFT averages are not totally correct.

It also has WOT being when only greater then 99% of TPS when it is more like greater then 80%.

It also only considers knock a issue when greater then 3 degrees, yet that could be enough to drop the timing from hi to low octane timing tables.

It also does not consider, injector pulse width/duty cycles, delivered torque and misfires,
which effect performance and tuning.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thank you for your response. Tell me then which or what and how I should analyze the data I get from autotap, and what information should I look to get (what variables) when running autotap. Oh, and by the way, I have an M6 not an A4, if that makes a difference

Thanks

Bill

<small>[ May 23, 2002, 09:16 PM: Message edited by: SS125 ]</small>

Sparky

I agree with John, that info (which I used faithfully for a year) is not totally correct.

Are you trying to tune for a maft? If so, give me a call, I'm local and would be happy to help!

Mark

Vettepartz

On my 99 C5 with A4, cell 0 seems to be only used for coasting with no g-pedal pressure. when the MPH gets to zero, it flips to the cell 19. For averaging the LTFT's, I have been only using cells 1-16. John from Team ZR-1 has this figured out to a science, and I would go by what he says.

MelloYellow

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"><strong>Originally posted by Team ZR-1:
That excel sheet you speak of averages all cells of 1-19 which skews the "ON g-pedal" / load cells so that LTFT averages are not totally correct.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">If Cells 1-19 skew the "ON g-pedal cells", what are the correct "ON g-pedal cells" to average?

Thx!

<small>[ July 08, 2002, 09:00 PM: Message edited by: MelloYellow ]</small>

Team ZR-1

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SS125:
<strong>[QUOTE]Thank you for your response. Tell me then which or what and how I should analyze the data I get from autotap, and what information should I look to get (what variables) when running autotap. Oh, and by the way, I have an M6 not an A4, if that makes a difference

Thanks

Bill</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Your welcome Bill,

I hate to say it but you have to learn how to use Excel so that you can write the math conditions so it can make the correct decisions in the data you exported from your scanner.

You might do a search on this forum since there is a lot of content about this subject also my forum has over 400 techie detail about all this tuning stuff.

Keep in mind the OBD-II protocol puts a lot of load onto the PCM and remember the computer in the PCM is less then 17 Mhz so the more PCM functions you ask the scanner to babysir, it can slow down the PCM and its internal buss from doing it's normal tasks which get real busy at higher engine loads.

If you already have scanned and have found that B1 (left head) and B2 ( right side) are about equal in values then there is no need to have scanner record both thus pick B1 functions and not B2 reduces PCM OBD-II load.

Not needed all the time but consider the PCM goes by what STFT has to say and it functions across a range of plus or minus 10% fuel trim. sO just because LTFT says one that does not mean STFT is only 1%, it may be 9% itself so I would suggest if you do 5 scans, at least 1 of them is recording STFT of at least 1 head until you understand how LTFT supports STFT and it feeds PCM as to how the engine will function for 10 minutes at a time.

You want, knock, total misfire, timing, trim cell, TPS (position angle), RPM, IAT, one LTFT, one s1 ( 02 before cat) heated 02, one heads avg injector pulse width, and if using a compliant OBS-II scanner it will properly support delivered torque.

ALWAYS have them in the same order of your recording so when you import it into excel your custom template can do the proper math to each parameter alsways found in the same column every time.

Team ZR-1

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MelloYellow:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"><strong>Originally posted by Team ZR-1:
That excel sheet you speak of averages all cells of 1-19 which skews the "ON g-pedal" / load cells so that LTFT averages are not totally correct.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">If Cells 1-19 skew the "ON g-pedal cells", what are the correct "ON g-pedal cells" to average?

Thx!</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Since I do PCM tuning I use MAF freq as my guide marks for they tell me which cells were used.
Each cell uses about 700 Hz.
By having my template chart by MAF freq it shows me for each cell what the engine load was, knock count, delivered Tq and LTFT, thus I then go into about any tuning table and converting ( or recording MAF in grams) I can tune for how each cell is functioning.
This way if I see cells 9 and 10 are lean, I know what freq that function in and then make the changes only to those MAF freq ranges.

As I mentioned bust down the cell matric to

Cold/hot Idle sub AC on and off
cells 0 to 5 slight lift of g-pedal
6-10 about highway speeds,
11-14 engine going into PE and
15 and 22, at this time MAF freq is hauling ***, about 8,000 Hz and going to 12.5K Hz.

Its all in the math decisions you make within your excel template.

Now you can see each groupings answers and make much better choices in your tuning.

Consider cell groups, each as a cell for getting on g-pedal ( higher freq), lifting G-pedal ( low freq) and if A/C is on or off since EPA thinks A/C on means more fuel needed and cause engine needs to deliver more current load to support load of A/C on.

I assume people tune for they want performance, not what happens when they lifting off g-pedal so as a minimum average cells 6 -15
and a compare of 15 and 22 for PE but at the minimum get rid of the TPS being greater then 99.6 in that template and at least make it 80% and greater.

Engine load and delivered torquw in your scans will show you via sorts that cells 0-5 are less then 10% of engine load being used.

Also if cruise control is on you'll notice at same speed lets say in 5th gear is not the same cell when cruise control is off.

We need a PHD today to understand all this stuff :-)

<small>[ July 09, 2002, 01:25 AM: Message edited by: Team ZR-1 ]</small>

ToplessTexan

Here we go again... <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />

The good stuff at C5 Forum is correct for MY 97-98, incorrect for later years. The original author put that together using his 98 as a reference some time back (a couple of years now?) so it's hard for me to be too critical. John seems to always forget that the meaning of the FTCs has changed in later model years, dismissing people's interest in understanding thier FTCs as worrying about FTCs too much and to just use the MAF. <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

The LTFT cells are functions of RPM and MAP along with the oddballs like WOT, idle a/c on etc.

Do a search if you're interested, there are some more thoughtful discussion of FTC and LTFTs here.

Jadeeglide1550

Great information John and Texan. I too was off and using the recommendations from the C5 Forum. I did however no use the 99.6% for WOT and had lowered, but not down as far as 80%, which I will now do. I noticed after tuning the car with the information from the C5 Forum that it did not seem to be as powerful, but I attributed this to my imagination. I also noticed that the car feels much more powerful when cold than when it goes into the Closed Loop Mode. LS1edit is helping to clarify things for me. I have also ordered the EFILIVEV5 which I will use rather than my Autotap. They show when scanning more paremeters, with EF..5 you get more scans per second.
Thanks for clearing up things for me and I am sure others appreciate it also. It is always a challenge to sort the misinformation from actual information that works and is correct.

MelloYellow

Thanks. I'll average cells 6-15 from now on for LTFT's. The 80%+ comment was aimed toward WOT runs, not avg'ing LTFT's, right?

Would it be true to say -10 to -15 LTFT's would have worse off idle and part throttle response than LTFT's closer to Zero?

MelloYellow

Thanks much! That's great info.

Any general recc's for my mods?
216/224 .558 114 Cam
Stock Heads
Long Tube Headers
LS6 Intake
9.6:1 C/R via thicker gasket
900rpm idle

Florida Heat & Humidity
Tricking the PCM via IAT @ 57* for more Timing

No KR in gears 2-5
I do see a good bit of KR in 1st gear with my old +15 -2 MAFT dialed in. Unsure how the +10/+2 may have changed that.

1st gear KR casued by being too rich?
Too much timing in 1st at RPM's below 4000?
Again, only about 3* KR in 1st below 4k and no KR in other gears. Seems tp be induced by 1st gear load? Only happens 50% of the time in 1st.

Thx!

<small>[ July 09, 2002, 02:26 PM: Message edited by: MelloYellow ]</small>

Team ZR-1

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MelloYellow:
<strong>Thanks. I'll average cells 6-15 from now on for LTFT's. The 80%+ comment was aimed toward WOT runs, not avg'ing LTFT's, right?

Would it be true to say -10 to -15 LTFT's would have worse off idle and part throttle response than LTFT's closer to Zero?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Depending on your mods and esp if you have cam and headers will dictate what the idle circuit must be tuned to. You will see a richer idle it A/C is on.
With 11.3:1 engine compression and the cam grind on my '99 C5 the best idle is with LTFT being about +3 lean, this prevents any surging.
Also if using a performance cam you may need to tune idle as to temp.
In my case the colder the engine is, the idle is set a bit higher then is scaled lower as engine goes to normal operating temp.

Yes 80% is a better TPS value to use as your condition for WOT then the 99.6 is when having excel do the math for you.

MelloYellow

ttt

wizkid

iTrader: (3)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MelloYellow:
<strong>Thanks. I'll average cells 6-15 from now on for LTFT's. The 80%+ comment was aimed toward WOT runs, not avg'ing LTFT's, right?

Would it be true to say -10 to -15 LTFT's would have worse off idle and part throttle response than LTFT's closer to Zero?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Why average cell 15 in there if you leave out 22?? Since both cells seem to be WOT cells? Or am I missing something?

ERic

MelloYellow

wizkid:
I was wondering about Cell 15 too for LTFT averages. Someone mentioned it's a high load cell, but not always WOT.

wizkid

iTrader: (3)

Good point. I went back through my latest log file, 24 mintues long with almost 16,000 lines logged <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> .

I noticed that cell 15 was only logged 119 times and of those 119 times it was used above 80% TPS only 19.3% of the time. High load would be accurate too. The maf (grams/sec) averaged 115.8 gm/s when in cell 15.

Compare that to Cell 22 in the same log.

Cell 22 was logged 252 times and of those 252 times it was used above 80% TPS 94.1% of the time. The maf (gm/s) averaged 242.13 grams/sec when in Cell 22.

So, I wonder why even have cell 15 kick in when the TPS is greater than 80% to begin with? Makes no sense to me really.

Eric

Team ZR-1

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by seanr:
<strong>The difference between using cell 6-15 to get a average LTFT compared to using cell 1-19 is very small so does it really matter? I get a 0.2% difference. The same goes for WOT O2´s using 80% or 99.5% I get the same average O2's.

<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That difference would depend how many PCM cycles were recorded, how many cells were load, non load and idle cells, I have seen as much as a 5% difference when they averaged 1-19 over just the load cells in PT.
You may have been in a worse case PT AFR lets say 10% ot the total PCM cycles, thus if that was 10,000 cycles, the sum is divided by 10,000 and the 10% cycles just got washed down in the total average and your unaware of the area that needs to be tuned.

Cell 15 is clearly a high load cell ( area uder most stress and place tuning for performance is needed) and again PE is not based on TPS alone, so again why I do not base tuning by cell but by load ( I use MAF Freq since cells use a certain range of the MAF freq range.
Being most are tuning for performance, cell 15 is more based to WOT load for tuning then it would be for PT and reason why people tend to get LTFTs tuned OK but not WOT.
Driving to work in traffic you'll not see cells like 14 and 15 so why include then for LTFT average as the norm and on the other side why only average WOT in cell 22 at 99.6% when it is the engine load to get you into pure WOT that makes or breaks you of getting best performance tuning.

So again instead of black/white of PT or WOT, how about adding a high load part of your math calculations within those templates ?

<small>[ July 12, 2002, 02:58 PM: Message edited by: Team ZR-1 ]</small>

seanr

Thanks Team ZR1. Your explanation sounds resonable. I will do some more testruns with different amount of load/PT/idle to see how much off it gets.

Why can't someone with the knowledge <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> make a excel sheet and a AutoTap cfg file to help all of us struggling to get the tuning done as correct as possible?

Thanks.

<small>[ July 12, 2002, 03:48 PM: Message edited by: seanr ]</small>

MelloYellow

Thanks everyone. Tuning my LTFT's using cells 6-15 seems to be improving my PT response.

Anyone want to comment as to why I only see KR in 1st gear below 4k RPM's during WOT?
Is this common? Due to load??
Or may the KR be due to over-rich part-throttle to WOT open/closed transition??

<small>[ July 12, 2002, 07:28 PM: Message edited by: MelloYellow ]</small>