VE tune with MAF ??

[Bruce Melton]

Ok, I spent lotsa time, gas and risked my license getting my AutoVE done.
The results are pretty good esp. the cam idle and low end performance.
However, the correction from day to day (fall weather?) is enough to mess up idle and cause drivability issues leading me to want my MAF back.
The air added by MAF is really contrary to the VE tune and stock MAF calibration as we know.
Is it possible or a good/bad idea to do AutoVE tune with MAF enabled?
For those of us intent on going back to MAF, why not?
Thanks for your critique--
Bruce

[Dirk Diggler]

I did this and went back to the maf becasue of what you are seeing. What I did was dial the ve table in first and on the same day dialed the maf in and I havent looked back since. I wouldnt do a ve tune with the maf enabled because you will soon see that you have to move the ve table almost like 4:1 (4 parts for the ve table to see any changes) and then when you unplug the maf you will end up with a super rich condition.
I actually got tired of fooling around with the tune on different days so I cant tell you how much the weather has swayed my maf tune because i have no desire to hook my WB up LOL. It was the onset of OCD for me

[tirekillinss]

got the same problem here in colorado, i set the B0120 table to 400 rpm, had to tweak a few spots in the MAF freq table to get fuel trims in order, but now all is good, atmospheric conditions change very fast here and don't want to reflash twice a day just to go for a cruise.......:beer:

[TAQuickness]

Or, if you'd rather stay in SD, you can use A0014 {OS3 or OS5}. I'm in OLSD and haven't touched my VE tables in weeks.

[Bruce Melton]

Or, if you'd rather stay in SD, you can use A0014 {OS3 or OS5}. I'm in OLSD and haven't touched my VE tables in weeks.

TA,

God created, topography, weather and climate changes so he allowed the MAF to be created to appease us.

Houston is likely more SD friendly.

Just my perspective from WI. where the weather sucks and you have to store your car 6 months of the year.
Bruce

[tirekillinss]

thank you Bruce, unfortunetly some of us live in cold winter snow/hot summer states, and everything in between, BY NO MEANS IS THIS A DISRESPECT TO TA(i've read a lot of his posts, 97% of the time, he's on the money), i spend a lot of time at BANDIMERE SPEEDWAY (not in my car), most of the people there have 4 different settings for race cars.....early spring....mid spring/summer...summer....fall... fall being the best air(most compettitive racers set up for richer condition in fall here).......i have not tried the custom OS yet, but plan on it....soon, EFI LIVE, imo, has been the best tuning tool available....PROPS TO THOSE RESPONSIBLE FOR EFI LIVE.... by the way TA, nice post on "GOOD KILL", you should have laid pipe on him, not your problem he bought the wrong car...............:cheers:

[TAQuickness]

TA,

God created, topography, weather and climate changes so he allowed the MAF to be created to appease us.

Houston is likely more SD friendly.

Just my perspective from WI. where the weather sucks and you have to store your car 6 months of the year.
Bruce

Know what they say about Houston? If you don't like the weather, wait 5 minutes.

The MAF has it's place and purpose. The biggest advantage it has is it offers a higher resolution for fuel tuning (think EPA).

My Dodge Dakota rolled off the show room floor MAFless...

Not trying to sway you either direction, just food for thought.

[bink]

Or, if you'd rather stay in SD, you can use A0014 {OS3 or OS5}. I'm in OLSD and haven't touched my VE tables in weeks.
okay, TAQuickness :D...what's A0014 ??

Hey Dirk!!! :wave:

[TAQuickness]

{A0014} IAT VE Multiplier
This value is multiplied with the values in the VE table, based on intake temp.
For example, if the VE Table value is 3.000 Grams*Kelvin/kPa, and the value in this table was 1.00 then the final VE number will be 3.000
But if you entered a multiplier of 1.01 the value will be 3.000 Grams*Kelvin/kPa X 1.01 = 3.030 Grams*Kelvin/kPa.

[Bruce Melton]

So I just can't get it going and damn I tried.

Completed SD tune now want to bring MAF back on so:

Created MAF log>
982

Then tried to do do a copy with labels and paste and multiply onto MAF table>
983

Will not paste and multiply.

Did a manual multiply which increased the MAF table values and took the PLX AFR to ~15.5>17. except on PE end where it was ~13.

So please, what can you tell me?
Thanks,
Bruce

[TAQuickness]

your labels don't match between the log and calibration. Change the log column from 8000 to Value.

Other than that, I can't help much. Where's Dirk?

[Bruce Melton]

TAQ,
Spot on. The changed table works. Column changed to Value,Value. It was a table that Sinister posted and I see widely copied> http://forum.efilive.com/showthread.php?t=671
With the change you suggested it pastes and multplies (PLX)>
987

Anyone have any ideas on correction factor. It almost seems like it should be inverse?

[NewV]

Anyone have any ideas on correction factor. It almost seems like it should be inverse?

I did my first MAF correction tonite and it appears the same to me. I tried it once with just standard BEN correction and another with SSpdDmn's spreadsheet at 80% of correction. Both times my BENs went from 1.03-1.04 to 1.09-1.11 and I went way too lean.

Bruce - Did you finally get your MAF dialed in?

Anybody else have any advice, I'm assuming I can use the same BEN calc I used for VE tune.

[Tordne]

BEN factor should work... Just thinking about a single cell in the MAF table (cause that's all my brain is capable of):

If the value in a cell (for a particular Hz) was say 6 grams/s and you were 10% lean on average in that cell, meaning a resulting BEN factor of 1.10. This applied and multiplied to that cell would make it 6.06 grams/s meaning that you are actually getting more air at that Hz than you had and therefore more fuel is required to maintain commanded AFR.

Sounds good to me - but I never tried this.

[Doc]

NewV, are your fuel trims off and zereo'd?


Just a few thoughts, observations related to MAF tuning that I have noted with the RR...

The pcm is as with the VE table (and many others) sampling the cells in the MAF table. You can litterally watch it happen realtime with the RR. As an experiment you can get the vehicle in one steady state, say idle and increase the value in a cell right next to the cell that you are getting readings in and you can see the effect.

[Alvin]

Anyone read in tutorial or help guide about "death valley" tunes? You can sorta overtune your VE to where the car is sensitive to weather changes.

I got my start in this buisness with 92-93 LT1 tuning. They are factory speeddensity cars. I made a few caculators with some good help from Mr. Moates on software end that would take TTS Datamaster log exports and do sort of a auto tune. By using these calculators it was very easy to see that if you targeted 0% exactly the car would feel off from day to day. The best way we found to get around it was to tune to say -5%. The idea was a lean car drives bad, where a slightly rich car still maintains pretty good drivablitly.

Prehaps you would see better results if you targeted say -5% w/ autotune.

[NewV]

NewV, are your fuel trims off and zereo'd?


Just a few thoughts, observations related to MAF tuning that I have noted with the RR...

The pcm is as with the VE table (and many others) sampling the cells in the MAF table. You can litterally watch it happen realtime with the RR. As an experiment you can get the vehicle in one steady state, say idle and increase the value in a cell right next to the cell that you are getting readings in and you can see the effect.

Yep, don't they (fuel trims) get zero'd out with every reflash?

Actually ran it today and it looks good now even made another small tweak at it seems to be working.

Just gotta get WOT done so I'll have VE and MAF done, whats next?

[Tordne]

The effect your seeing Doc is the way the PCM interpolates between rows/columns in a table. It does this to try and balance between cells and derive a more accurate metric for the actual position your RPM, Hz (or whatever the scale may be) is.

A good example is the VE Table. Say for simplicity sake that your car is currently sitting at 2200 RPM and 77.5 kPa MAP. Because this doesn't sit right on a row/column intersection the PCM interpolates between the urrounding cells. In this case it will uses values from the 2000 and 2400 RPM rows, and the 75 and 80 kPa MAP columns to provide the actual VE value used by the PCM for fueling.