New to tuning? Step inside

[blue_falcon]

Max best timing is Max best torque/power

If you add too much timing the car will fire too soon, and you aren't gaining anything and could obviously damage the motor

[tomaSS]

A couple questions regarding the VE portion:

1. Should the VE table be smoothed after each "round" of changes? I did this after the first two logs and might have just created more work for myself.

2. Approximately how many logs and changes to the VE table before the trims are between -4 and 0?

3. I noticed that the VE cell values increase as the MAP and RPM's increase. If one cell is considerably greater than the surrounding cells, should I decrease it to more closely match what is around the cell?

4. What is the "typical" maximum VE cell value you should see?

Thanks in advance.

[JimMueller]

I used a wideband, but this is what I did:

1. I personally smooth each time, but I don't think it's necessary. I don't stick with the raw polynomial results, however. I have a spreadsheet which compares the poly value to the range the value should be within to stay within my AFR range. I don't let the value fall outside of these bounds.

2. I had a real hard time getting mine to be consistent. Things seemed to be better after I re-attached the loose PCV tube on the passenger valve cover : Probably 6-10 complete logs to be comfortable they are stable.

3. The adjoining cells should be smooth not spikey. If it's a dip, it should look like a U, not a V. You should tweak the spike and the values around it to smooth it out.

4. I'm guessing that the max VE cell value you'll see for a stock vehicle would be ~100-110. I think I've seen VE tables from FI cars which are in the 150+ range.

[Tony766]

Newbie questions concerning LTFT tuning,

1) when tuning your LTFT's, do you need to drive 100 miles each time you edit the VE tables? I turned off my MAF sensor,reset my fuel trim and drove 100 miles as suggested. I did my first edit, dumped changes to VCM, and drove/logged for approx. 15 minutes. MY LTFT's were still very positive, wondering if changes need more time to take effect or if car is very lean, and needs more added to VE tables.

2) do you need to reset the fuel trims each time you dump new VE tables to the VCM?

3) do you average the LTFT readings on the histogram display or use last value?

Am I correct in assuming that by editing the VE tables (+), we are increasing the pulse width on the injectors, ie adding more fuel.

please help.

[BQuicksilver]

Tony 766,

I'm a newbie as well, but I think I've got a reasonable grasp of part of this. If a vet disagrees with me, listen to them.

1) You'll need to make several rounds of changes to get the LTFT's right. You'll likely drive 20-40 miles just logging between rounds, which is good enough. However, once you feel you have the LTFT's where you want them, them do a full 100miles afterwards before moving to the next step in your tuning, that way the car is not still learning the LTFT's while you're adjusting other areas. Of course 100miles is optimal between each round with LTFT's, but why make sure the car is totally adjusted until you think that this round may be your final LTFT tuning shot.

2) Yes, I reset each time, that way your data only reflects the most recent tune. You don't want the scanner to show high LTFT's because the numbers are a reflection of a previous edit. You want your data to reflect your current state of tune.

3) Average, otherwise you may just be looking at transient values. You don't want to edit on a transient LTFT of +9 when the average of your tuning run was +3.

Hope this helps.

[BQuicksilver]

A few questions of my own:

1) Why exactly do you need to unplug/disable the MAF for tuning?

2) I seem to have done okay adjusting my LTFT's with the MAF unaltered. I'm sure I made an error here, but I need to know why.

3) How much does temp/humidity affect the LTFT values? In other words, will I need a separate tune for 40deg,50deg,60deg,70deg80deg,90deg, etc....or will I only need tunes for 40deg,70deg, etc? Just curious what the rule of thumb is here.

[WS6FirebirdTA00]

ok so say i have a stock MAF and i unplug it and get my fuel trims right where i want them. then i plug the maf back in, what will that then do? do i need to adjust anythign else or no? will that change any numbers?

[ozorowsky]

once you get all your ltft's slightly negative you will need to scale maf table until ltft's are back approximately where your ltft's were before you plugged the maf back in. But why would you want to plug the maf back in?

[WS6FirebirdTA00]

i have been reading about the maf and how it accounts for the air. what are the advantages of leaving it off. honestly i dont really understand why i should keep it or get rid of it. if it is gone wont it effect my tune in different weather? that is what i read on ls1tech. i am no expert on this im just trying to get things figured out before i start to tune

one more question, i keep reading about having to change something about the o2's with headers? what is that about. you can email me or pm me on tech or im me on instant messanger.

ws6firebirdta00 sn and user name on tech and @yahoo.com is my email. i do have some real good basic concepts, i have been using predator to tune my car so i know what things are and what they should do but know i know what and why i need to change things. thanks

[mediumrareintexas]

One newby to another....eliminating the MAF allows more air to enter the engine and is one less item you have to consider when tuning. The down side of this is that if you live an area that requires an emissions test, you will fail that test.

You could have different tunes. One that you use for the emissions test with the MAF installed and one without.

[WS6FirebirdTA00]

i have no worry for emission inspections, i do them. all that emission stuff is off my car. i know it lets more air in, right now i have ported ends. but if i tune everything else and the i can go to the maf tables and scale it and get it back to being right im not seeing the hard part there. plus i dont have to worry about having different tunes for different weather. if all i have to do is go back through and make sure the ltrims are all right i dont see the big issue. however from everyone talkin it seems to be a bigger deal than just going back in and tuning and scaling. from what i keep reading it really doesnt seem to much to do just more difficult. im up for that challange if it is jsut somethign that takes up time, i have pleanty of it. i liked telling the guy at predator what to tune on my car after mods, but after doing research i think he did it wrong. i think the maf tables are not done right at all which could be the reason for my dealy sometimes in my car and inconsistancy to different days. we will see

[A2000SSinJersey]

Great info............especially for a newbie

Its making sense already and I dont even have the Package yet..LOL

Tanxxxxxxxxxxxxxxxx

[V-10_Killer]

Open up your editor and go to Edit>Engine>Airflow and look under MAIN VE click on Primary VE vs RPM vs MAP. Click on that.

Question. If the computer drops to using the secondary VE tables when the MAF is unplugged, then why are you modifying the Main VE table. Shouldn't you be modifying the secondary, then when done, saving the secondary over the primary?

[12secSS]

Question. If the computer drops to using the secondary VE tables when the MAF is unplugged, then why are you modifying the Main VE table. Shouldn't you be modifying the secondary, then when done, saving the secondary over the primary?

The tables from the histogram and the Primary VE table both match exactly, so it is better to make you changes to the Primary first, then copy the needed rows over to the Secondary. Otherwise if you do it the other way around and need the Primary VE table, you will have to guess the rows that the Secondary table is missing from the Primary. Better to have the Primary dialed in and copy the needed rows over to the secondary after making changes. This is how I do it on our 1998 Z28 race car and it has worked out excellently.

[bmfcamaro]

i believe its 2 no mil light

[V-10_Killer]

The tables from the histogram and the Primary VE table both match exactly, so it is better to make you changes to the Primary first, then copy the needed rows over to the Secondary. Otherwise if you do it the other way around and need the Primary VE table, you will have to guess the rows that the Secondary table is missing from the Primary. Better to have the Primary dialed in and copy the needed rows over to the secondary after making changes. This is how I do it on our 1998 Z28 race car and it has worked out excellently.

But doesn't the PCM use the secondary tables while the MAF is unplugged?

[12secSS]

Yes, but when you use the polynomial smoothing, it is better to use the primary table for that (IMHO). Then just transfer the corresponding (every other) row from the primary to the secondary.

[Screamn03]

Hey Oz,

I have a good link on disabling the rear 02s if you want to add it/quote it:




-Mike-

[ozorowsky]

Updated. Thanks guys keep the tips coming!!!

[matts_222]

If you guys haven't see this yet, check it out. It's a lot like the guide in this thread.

http://www.ls1tech.com/forums/showthread.php?t=284479