As I continue to tune VE for SD mode, I am having a few questions come up...

#1 - does increasing VE table values add fuel or subtract fuel? I was thinking subtract, but now I am thinking the opposite. Silly me. Which is it?

#2 - what would cause MAP values to stay < 30 while revving car in neutral. Shouldn't they pass 30 (idle MAP)?? I am getting a weird stutter on light throttle, doing it this way. If I give it more gas, the RPMs increase, the MAP stays the same and the stutter remains too.

Is this a product of VE or spark? How can I fix this stutter/low MAP reading?

#3 - I'm also getting a slight stutter/bog if I give it a hard punch off-idle. I'm thinking this is from VE tables being off, but I'm not sure if it's too lean or rich. I'm "leaning" towards too lean. Any thoughts?

Thanks!

 

Can someone help me at least with #1? Upping VE values leans or fattens?

 

Have you tried using VEMaster to help you out.
It will only work if your BLM's are not to widely split.

Check out this link for details:
http://www.akmcables.com/vemaster.htm

Edit: Just saw another post that you are already using it.
I'll leave the link for others to use.

I was under the impression that increasing the value fattened up the fuel ratio but you have me second guessing myself now.

 

Jeff, thanks for the help. Yes, I'm using VEmaster and it's helping a lot. But I still need some fine tuning.

I discovered that raising the VE values does indeed fatten it up. Basically it's telling the PCM that the engine runs more effeciently, that it can take in more air, thus it would need more fuel...

I still need help with #2. I am getting MAP values of like 22-25 in Freescan, which is lower than the idle value of 30--simply by applying very light throttle. I am wondering if this is an artifact of timing, but don't know whether to add or subtract it advance.

Can anyone help?

 

What is your BAR? MAP should be roughly 30% of your BAR reading.
So if your MAP is reading 22-25 then your BAR should be 73-83.

My BAR reading stays at a pretty constant 1.02....AKA 1 atmosphere.
This is the normal reading for the BAR.

I wonder if an exhaust leak could cause that problem.
Hmmm...I guess timing could cause that but I'm not sure.
What type of cam are you running if any?