VE tune

[jackal2000]

how can i do a VE tune with my MAF disconnected if my car wont run? lol sounds silly but its the issue i have.

[AaronGTR]

It should run with the MAF disconnected. It just goes into speed density mode. It won't run very well and you may have trouble keeping it running at idle, but it should be able to drive at low throttle and cruising speeds. Thats is where you would be doing your scanning in order to make adjustments to the VE table.

I did have problems doing this myself this year though. I've changed so much on my engine that affects VE (cam, heads, SC, headers, etc) that my stock VE table is nowhere near where it should be, so I can barely keep the car running if at all while in SD mode. The closer you are to stock, the closer that table will be and easier it will run, and conversely the more mods you have the more it will need adjusting. The trick is to try and get your fuel trims as close to zero as possible first before VE tuning. Plus or minus four either way should be close enough. If your trims bounce around a lot though and go +/- 10 for example and go positive and some places and negative in others then it will be harder.

I found I could get my trims close while at idle in one Kpa cell in the IFR table, but while idling in gear or cruising the engine would be under load so the Kpa cell would change and the VE would change and my fuel trims would be off. I could get one but not the other. This might require me to make some minor adjustments to the VE table before even being able to do a full VE tune... I don't know yet. I've been reading on the subject but I need more time and testing. Unfortunately I didn't have much time to test since I had to put the car in storage for the winter, so I won't be able to figure it out until spring. :(

[lvemy3100]

I read in your post on gmv6pcm that you had your VE table modded by some "tuner" that you swear to never go to again.. my suggestion to you is to put your VE table back to stock and see if that allows you to be able to run the car without the MAF connected... and I guess for s&g save the current file that is in your PCM if for some rediculous reason it wont run with a stock VE... if you CAN get it to stay running with a stock VE well then bingo you should be all good...

HTH

[jackal2000]

i'll have to try reverting the table back to stock because i cant get the car out of park without it dieing.

[Sprucegagt]

The trick is to try and get your fuel trims as close to zero as possible first before VE tuning. Plus or minus four either way should be close enough. If your trims bounce around a lot though and go +/- 10 for example and go positive and some places and negative in others then it will be harder.
(

Also, IFR tuning is not required nor recommended except in specific circumstances. Yes, it was the first method used for tuning, but it has since fallen out of favor since MAF and VE tuning do a much better job. Keep your IFR table stock if you have stock injectors or adjust it only if your using larger than stock injectors.


EDIT: Jackal2000: Your about 2 hours from me depending on traffic. If you want to meet up one weekend, I wouldn't mind helping you out with your VE tuning.

[jackal2000]

WRONG. VE tuning must be done starting with a stock MAF and VE table. Doing preadjustments only produces errors in your tables. When doing VE you must follow the procedure in JerryH's Tuner notebook. If you follow it you won't screw up your table.

Also, IFR tuning is not required nor recommended except in specific circumstances. Yes, it was the first method used for tuning, but it has since fallen out of favor since MAF and VE tuning do a much better job. Keep your IFR table stock if you have stock injectors or adjust it only if your using larger than stock injectors.


EDIT: Jackal2000: Your about 2 hours from me depending on traffic. If you want to meet up one weekend, I wouldn't mind helping you out with your VE tuning.

that would be excellent, i didnt realize we were that close. i'll PM you...

[jackal2000]

i went back to the stock VE table, still no luck. it'll only idle for about 10 seconds, not nearly long enough to scan.....

[Sprucegagt]

EDIT: You know what forget it. I'm cleaning up this thread.

[jackal2000]

i got it to idle last night for a while, had to hold the throttle open a bit. im gonna reduce the rpm cells 800 and below by -.1 (each kPa cell) and see what happens. it locked in at -30 LTFTs last night....

[Sprucegagt]

Yeah your going to have to work on it. I do want to see what I can do with it.

[jackal2000]

Yeah your going to have to work on it. I do want to see what I can do with it.
as do i lol

[mfuller]

Out of curiosity, what is your commanded idle set at? That cam lessens maifold vacuum I'm sure....

[jackal2000]

Out of curiosity, what is your commanded idle set at? That cam lessens maifold vacuum I'm sure....
850rpm

it sure does, i idle at 60-70kPa

[jackal2000]

VE tune complete....Andy ownz at teh tuning. i couldnt have done it without ya man!

[Sprucegagt]

No problem Jon. That cam is NASTY!!!!! It doesn't sound like a V6 AT ALL!!!!

[xonelith]

Awesome! How much of a difference did you notice with and without the MAF? I hope to do this in the spring:) Hopefully, if all works out, I can get a good VE tune that is good for Winter and Summer (maybe high hopes).

[jackal2000]

the only difference after the VE tune is that the car will run with no MAF, it doesnt really care for decel though. with the MAF plugged back in it is a hair lean which shouldnt take much to correct. during the tune we never went above 40% tp (IIRC) which is below my powerband so i cant really say if there is a power difference.


good luck getting yours done, im sure you will have the same headaches we had. lol

[Sprucegagt]

One other thing I noticed is the LTFT's were very consistent between FTCs. Plus previously the car was a little rich and is now lean with the MAF plugged in. Some MAF tuning will fix that though. But getting PE straightened out will be the fun part. Also, the car does not like decel enleanment at all.

[jackal2000]

But getting PE straightened out will be the fun part. Also, the car does not like decel enleanment at all.

i think i'll do the driving while YOU hold the laptop for that! lol

[Sprucegagt]

i think i'll do the driving while YOU hold the laptop for that! lol

Oh come one, just once! PLEAAAAASSEEE!!!! lol

[eric99gt]

Andy wanna drive up to NEPA....I'll pay your way in beer lol. I've just been so busy with school and crap can never get around to tuning this thing. Dumb question but why would you want to run the car without the MAF?

[jackal2000]

Andy wanna drive up to NEPA....I'll pay your way in beer lol. I've just been so busy with school and crap can never get around to tuning this thing. Dumb question but why would you want to run the car without the MAF?

you dont and probably wont, but if your MAF fails you want a driveable tune. on a stock engine the MAF is really just an extra part that is not needed really. thats my understanding anyways.

[Sprucegagt]

VE tuning sorta lays the ground work for the rest of your tuning. Yeah it allows the car to run without a MAF but it also makes MAF tuning easier by keeping your LTFT pretty constant between fuel trim cells. You don't get the big + then - (and vice versa) swings just from going from idle to cruise to heavy load (aka WOT).

Eric99GT: As for my tuning help, I would be glad to give it. But you'll need to come to me. But thanks for the beer offer.