Is a smooth 3-D VE table desirable?

[SSbaby]

Hi, thanks for a great forum. :)

I have a cammed LS1 M6 with a MAFless tune. I was wondering whether it would be desirable to have a smooth VE table when viewed in 3-D graph format (similar to the spark smoothing table) using Flashscan?

Thanks,
SSbaby

[SSbaby]

I guess, judging from the overwhelming response :shock: , the answer is dependent upon the LTFT reading within each logged MAP LTFT cell value that would have a direct influence upon the VE table values!

e.g. If the LTFT value for the MAP LTFT cell is 12% rich, then you would subtract roughly 12% from the corresponding VE table value to attempt to get the ideal theoretical 0 (zero) value for LTFTs (assuming you have a WO2 A/F meter connected to your PCM).

[SSbaby]

OK. I'll answer my own question. A smooth VE table combined with a smooth Spark table(s) will give you good driveability.

It is possible to get your LTFTs down to near 0 (zero) across all the cells and have a smooth VE table as well.

I've finally had the chance to test my theory... no more lumpy on/off throttle engine responses.

[mnotx]

I would love to see a picture of your VE table.....and spark table for that matter. I am a novice interested in learning.

[SSbaby]

I would love to see a picture of your VE table.....and spark table for that matter. I am a novice interested in learning.

I'll try to post it up within the next few days...

Smoothing the spark table is easy thanks to the smoothing/blending feature in Flashscan.

[mnotx]

Thanks! This forum has been a great learning experience.

[SSbaby]

As promised, here are my VE and Spark graphs... (I run MAFless, cam 224/224 110 lsa)

http://images5.theimagehosting.com/VE.1.jpg

http://images5.theimagehosting.com/Spark.1.jpg

[johnsZ06]

What are the advantages/disadvantages running MAFless?

[SSbaby]

What are the advantages/disadvantages running MAFless?

Adv:

The MAF restricts airflow by a small amount ~ 5 rwkw. Therefore running MAFless = more power! :)
Don't need to tune the MAF table. More attention to VE table is required.

Disadv:

MAP sensor cannot sense air density, therefore cannot adjust fuel accordingly when adding things like cold air intakes, etc... You would need a retune for every modified item that alters the incoming air density.
The PCM can only read from one spark (Lo-Spark) table unless the PCM's OS is reflashed.
Small fuel economy penalty (not worth worrying about).


Other than that, much of a muchness as both configurations can be tuned to compensate for changes in altitude (barometric pressure).

More reading from popular hotrodding online mag, for those interested: http://www.popularhotrodding.com/tech/0403phr_hemi/index.html


Unlike an LS6, which has a mass air system that allows the computer to adjust the fuel flow for any given airflow so that the mixture is always right (theoretically at least), the Hemi has a speed density system. This means that any increase in airflow into the engine goes unseen by the rest of the system. If a modification is done that increases mass airflow, such as a cold-air package, the computer has to be reprogrammed accordingly.