VE Table - Normal Driving

[z06corvette]

I'm looking for some guidance. This is my first time to post and my first time to tune...

I have started modifying my VE Table to tune for normal driving to lower LTFTs (LTFTs are 18-20) on my untuned heads and cam 2002 Z06Corvette.

Do I modify the whole VE Table, or just the columns for the lower RPMs, or please advise otherwise. ???

Thanks

[Casey]

The trick here is to drive with an "easy" throttle and try and cover as many cells as you can in the histogram.
That will give you a better picture of where things need to be tuned.

If you changed the cam/heads you will have to make changes across the entire VE table as you have now changed the ariflow characteristics of the motor.

Pick small sections of the VE table to work on. Use the histogram as your guide. If you are +18 in one area apply a +10% change to the VE table. The idea is to make corrections without over shooting your values.

Then go back an log/test again to make sure you are moving in the right direction. An engine is considered well tuned if you are + - 4% on your LTFT.

It will take some time to make all of the needed changes so be patient. Always save the previous calibrations and make notes on what you changed in case you need to go back a step. Within a few hours you should have your VE table very close.


Ken

[ZUKI]

So Ken, you suggest leaving the IFR table stock, and tune off the VE table?

[Casey]

The IFR should reflect the actual injector flow rate.
While some folks use it for a "quick tune" it should be tuned first to the injector mfgrs flow specs.

That table is supposed to take the place of a vacuum regualtor. If there is a vacuum regulator all of the values on that table should be equal.

Then anything else should be tweaked with the VE table.

Lying on the IFR has the same effect as lying on the MAF table. Sure it will work, but the main idea here is to get rid of any mis calibrations after you change something.


Ken

[JCMGTO]

Ken,

So then do you use the histogram averages to set your VE. Since the LTFT's will vary all the way through. Sometimes I will see -8's and -3's but have an average of -5. I also have variences between Bank1 and Bank2. But that flucates as much as the LTFT's do.

Also any updates on the widebands?

[MNR-0]

CAn I use the VE table to manage the LTRIMS at idle even if I have a MAF? Is the VE table used at all other than checking against the MAF? As that point does the VE table override ther MAF?

[Dragman]

The IFR should reflect the actual injector flow rate.
While some folks use it for a "quick tune" it should be tuned first to the injector mfgrs flow specs.

That table is supposed to take the place of a vacuum regualtor. If there is a vacuum regulator all of the values on that table should be equal.

Then anything else should be tweaked with the VE table.

Lying on the IFR has the same effect as lying on the MAF table. Sure it will work, but the main idea here is to get rid of any mis calibrations after you change something.


Ken

So if I understand this correct if I have changed IFR 15% to get my LTFT locked at 0 at WOT, I should do this in VE at the points that are causing the problem in VE table??? Or should I only do this for idle and part throttle??

[Casey]

So if I understand this correct if I have changed IFR 15% to get my LTFT locked at 0 at WOT, I should do this in VE at the points that are causing the problem in VE table??? Or should I only do this for idle and part throttle??

If you are using a MAF, you only need to tune the idle and part throttle VE parts of the table (4000rpm and below).

If you are not using a MAF you have to tune the entire operating area of the table.


Use the LTFT histogram to see where the problem areas are and tune accordingly.

Ken

[MNR-0]

OK. Im a little confused.

I have a MAF.

Assuming stock IFR, MAF and VE tables I have positive fuel trims.

What should I modify to tune the trims?

Do I rescale my IFR?
Do I rescale the VE table?
Do I do both?

[Casey]

Hi MNR-0,

Treat the entire car as small sections. Each table in the editor is used to tune "something". For every component you change or modify, work with it's associated table.

If you made no changes to the injectors or fuel pressure, leave them alone.

If you are using the stock maf, leave that alone as well.

If you changed the airflow dynamics of the engine (headers, cam heads, etc) make your changes to the VE table.



Does that make things a little clearer?
Ken

[MNR-0]

Hi MNR-0,

Treat the entire car as small sections. Each table in the editor is used to tune "something". For every component you change or modify, work with it's associated table.

If you made no changes to the injectors or fuel pressure, leave them alone.

If you are using the stock maf, leave that alone as well.

If you changed the airflow dynamics of the engine (headers, cam heads, etc) make your changes to the VE table.



Does that make things a little clearer?
Ken

Hi Ken,

I shall give it a go. I rescaled my IFR to get negative fuel trims. I figured a MAF would invalidate the VE table somewhat. I shall try rescaling the VE table for under 4000RPM instead and see if that makes similar changes.

I would prefer to use the VE table as it makes sense. I want to do it right. Ill post my findings when I have done the work.

Ken,

Very OT, I want to talk to you about HPTuners for the OZ market. I have 2 tuning shops that want to purchase PRO from you. One wants to to become the Eastern seaboard distributor.

Pop me an email.

[MNR-0]

OK. Some feedback. Reset my IFR and PE back to original and modified the VE table.

1st adjustment +5% across the board
result: no effect on LTRIMS

2nd adjustment +15% up to 4000RPM
result: no effect on LTRIMS

In my case they just done seem to work with the MAF. I have to say empirically that its all MAF or no MAF on my Holden 2004 Monaro.

[TT_Vert]

OK. Some feedback. Reset my IFR and PE back to original and modified the VE table.

1st adjustment +5% across the board
result: no effect on LTRIMS

2nd adjustment +15% up to 4000RPM
result: no effect on LTRIMS

In my case they just done seem to work with the MAF. I have to say empirically that its all MAF or no MAF on my Holden 2004 Monaro.

i have an 00 C5 and i have the exact same problem. At idle my Ltrims average -7 or so, i changed ve drastically to see if it;d even affect anything and it did not. ANy ideas?

Dave

[Screamn03]

Treat the entire car as small sections. Each table in the editor is used to tune "something". For every component you change or modify, work with it's associated table.

If you made no changes to the injectors or fuel pressure, leave them alone.

If you are using the stock maf, leave that alone as well.

If you changed the airflow dynamics of the engine (headers, cam heads, etc) make your changes to the VE table.



Does that make things a little clearer?
Ken

Ken,
I couldn't agree with you more. This was my inital tuning aproach because it's the logical one. My problem is that the VE table seems to do nothing at all in my case as far as affecting fuel trims. I seem to believe that there is something different between cars or years because I hear that some people have success with this approach and others do not. The VE does seems to affect throttle response, almost like in my case the VE table is like an accelerator pump. I'm willing to do whatever it takes to resolve this as I see it will greatly benifit the community.
Thanks
Mike

[SideStep]

:lurk:

[Screamn03]

What happened, did I kill this thread? ??? ;D

[MNR-0]

I dont think so. I reckon no-one know the answer. I will get around to doing my own VE tuning and go MAFLESS one day when I get a cam. The MAF just owns too much of the tuning.

[marc_w]

I have the same results when tuning with VE vs the IFR table...... VE doesn't seem to respond in the LTFT readings.

You guys are resetting the fuel trims, right?

I *honestly* don't remember if I did or not when I was tweaking things.

[AnotherUser]

I dont think so. I reckon no-one know the answer. I will get around to doing my own VE tuning and go MAFLESS one day when I get a cam. The MAF just owns too much of the tuning.

My mafless hotcam car runs sweet.

[Screamn03]

I have the same results when tuning with VE vs the IFR table...... VE doesn't seem to respond in the LTFT readings.

You guys are resetting the fuel trims, right?

I *honestly* don't remember if I did or not when I was tweaking things.

I've tried it both ways and the LTFT always settle in the same spot. The only way I can get the LTFTs to change is by adjusting the IFR which I've always thought was a dumb idea because I haven't changed anything to do with the injectors.

Need the MAF disconnected