Ve done is more than 10% maf scale normal?

[Stonewall]

OK I'm pretty much a new guy to electronic tunes. I've done the VE tune and all trims ltft and stft look good running open loop. I've re-enabled closed loop and tuning my MAF based on the open loop tune. Been reducing MAF table in 2% steps from 4000Hz to 8000Hz and my LTFT's are slowly moving down. I have now reduced the MAF table by more than 10% and my ltfts are still - 2 to - 9%. My question is, is this normal? I'm wondering if I'm doing something wrong here. Why do I have to reduce my MAF table by this large amount to get my LTFT's in order.
Thanks,
Jerry

[bigbrian442]

Did you read Russ K's post on MAF tunning for the V6 cars? HE leaves the VE table alone and just tunes the MAF. It works quite well.

[Stonewall]

Yes I have and don't agree. So I guess I'm on my own. Not that that method isn't a good one. I just feel that modeling the MAF in the VE table is the right way to do it. After all if your MAF does fail you would at least know the car will still perform half way descent.

[98gtp]

OK I'm pretty much a new guy to electronic tunes. I've done the VE tune and all trims ltft and stft look good running open loop. I've re-enabled closed loop and tuning my MAF based on the open loop tune. Been reducing MAF table in 2% steps from 4000Hz to 8000Hz and my LTFT's are slowly moving down. I have now reduced the MAF table by more than 10% and my ltfts are still - 2 to - 9%. My question is, is this normal? I'm wondering if I'm doing something wrong here. Why do I have to reduce my MAF table by this large amount to get my LTFT's in order.
Thanks,
Jerry

you need to reduce it that much because the tuning you just did to your VE table is being ignored, and your maf table just needs that much work. aslong as there is no mechanical issues, this is normal behaviour.

[Stonewall]

OK that makes sense thanks.

[bigbrian442]

you need to reduce it that much because the tuning you just did to your VE table is being ignored, and your maf table just needs that much work. aslong as there is no mechanical issues, this is normal behaviour.

Whats the point in tunning the VE table then?

[Stonewall]

Tuning the VE table in open loop is actually creating a profile of what the MAF should be. Once you know that the stfts and ltfts are in line using that table without the MAF you now enable PE and scale the MAF table to get the ltfts back in line. Once your there you know for sure the MAF table is correct.

[98gtp]

Whats the point in tunning the VE table then?

the only benefit i see is that if the MAF fails your car still is driveable.

[MMGT1]

I know I've said this WAY too many times but, a tuned ve table will save you a 200+ dollar tow if your MAF fails. Happened to me guys

[Phantom]

Without a wide band you should not tune above 7500hz. Add the filter ([SENS.121]>14.6) and when you have some of the trims getting closer to -1 to 1 and others that are much higher copy the histogram results to a spreadsheet twice and then delete the the larger values and multiply by half. For the larger values delete the smaller ones and then multiply by %.

[JerryH]

The why or why nots of VE tuning are well discussed. The yes or no's of if it works are also well discussed. The answers are known simply as "it is car make/model/year specific".

The amounts that the VE varies is simple to answer... it depends on the car and mods. The more you mod, the further off the stock VE tables are. Mine are off by as much as 24% in some areas. The basic same precept can be applied to MAF tables. A turbo with LQ4 MAF would be easily off by as much as 40%... why? Becuase it could in theory flow as much as 40% over stock under extreme conditions.

Its not black magic if you think about it a few seconds.

[Stonewall]

Without a wide band you should not tune above 7500hz. Add the filter ([SENS.121]>14.6)

What does this filter do and why is it needed? I see it's commanded afr above 14.6 can you explain please.

[Phantom]

That way it will not have Performance Enrich in the histogram throwing the LTFT and STFT off since it will command a richer than 14.7 AFR.

[Stonewall]

Oh I see. I just disable PE all together. Set pe enable % TPS to 100 across the whole table, then copy the high octane timing table to the low octane table because I think when in open loop it uses the low octane table. Then unplug the MAF.

[johnh]

VE table is being ignored

My GTP doesn't ignore the VE table--it makes a difference. Some GTP PCMs ignore it, I know the 04 doesn't. My car won't run with a zero'd out VE table, other years do--apparently GM in its infinite wisdom has changed a few algorithms...

That being said, you really don't need to mess with it much unless you're fairly modded (rockers, headers, cam etc.)

Are you using a Wideband? You don't need to disable PE if you are...

[streetcar]

VE has the largest affects on AE and DE...

On 98s it apparently is used as a sanity check - drive the car a few miles with a zerod VE table, it will cut out, set a MAF DTC, and will not start until cleared.

[JerryH]

My GTP doesn't ignore the VE table--it makes a difference. Some GTP PCMs ignore it, I know the 04 doesn't. My car won't run with a zero'd out VE table, other years do--apparently GM in its infinite wisdom has changed a few algorithms...

That being said, you really don't need to mess with it much unless you're fairly modded (rockers, headers, cam etc.)

Are you using a Wideband? You don't need to disable PE if you are...

On my '99 it also is being heavily referenced and used. I see a 4 MPG difference between having a tuned and untuned VE table. Car idles and starts better as well.

[Stonewall]

Hi John,
No my wideband is not installed so I'm trying to make the best of what I have at the moment. Disabling PE seemed to be the best way to go.