Tuning the VE table safely

[The Granny]

Finally got my car ready to test out, and I've got a base tune from Cal. One of the first obvious things I'm seeing on my 93/alky combo is the need to get the VE table more accurate, i believe my first pass in the car it was rich the entire time (O2 Corr. around -10%). I messed with some of the cells a little bit, I didn't want to make too much of a drastic change and rich pulling too much fuel, so I made small subtractions and am ready to test again. I want to reduce the possibility of any knock while I'm trying to dial in my actual a/f to reach its target numbers, so one thing I just thought of doing to help that would be to pull timing. I was thinking about trimming the entire timing table 10-20% to achieve this, but I am unsure if the method I'm talking about is logical. Once the VE table is more accurate and O2 Corr is within +\- 5%, I'd add the timing back in.

One question I have with this approach is will the retarted timing have an affect, if any, on the actual a/f? I couldn't see it happening but who knows. I'm out of town so can't take my car out to test any of this out, so I figured I'd post about it and see what you guys think.

I'm also only running 17 psi boost, my combo should be in my signature.

Giancarlo


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[HighPSI]

Pulling timing can effect your air fuel ratio. You say it's pulling fuel, but is the actual air fuel close to the target? If so, you can tweak the'VE table if you want or let the adaptive learning take care of it for you. As always, you can contact me on my cell number printed on the ECU i f you need anything

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[The Granny]

Pulling timing can effect your air fuel ratio. You say it's pulling fuel, but is the actual air fuel close to the target? If so, you can tweak the'VE table if you want or let the adaptive learning take care of it for you. As always, you can contact me on my cell number printed on the ECU i f you need anything

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Gotcha.. The actual a/f is richer than the target, I cant remember by how much but I know it isn't anything crazy, nothing more than 1.5x (units?) off from the target. I've got the adaptive learning feature on, I haven't messed with any of those parameters you provided in the calibration file. But after multiple hits in the car I noticed the actual a/f is still richer than the target, so I figured I might need to do something on my end. I wish I had my laptop with me so I could look and let you know exactly how far the a/f is off from the target. What would you say is an acceptable % error in a/f ratios? Or rather, how many units should I let the actual a/f differ from the target at any given time? I do understand that as the car is under more load at higher RPMs and MAP that tolerance should be tightened up some more. That's why I'm wanting to get the fueling from 0-17 psi precise before I increase the boost.

Thank you Cal, if I ever do find myself in a jam I know I can contact you and you'll help me out. But I'd like to see what I can learn on my own at the same time, this stuff is very interesting to me


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[HighPSI]

Duplicate post

 

[HighPSI]

Gotcha.. The actual a/f is richer than the target, I cant remember by how much but I know it isn't anything crazy..... What would you say is an acceptable % error in a/f ratios?

It should be within about 1/4 of an A/F. A ball park fix, since we're posting back and forth vs talking on the phone (real time), I would remove 10% fuel from about 200kpa on up and around 5% from 150kpa up to 200

 

[The Granny]

It should be within about 1/4 of an A/F. A ball park fix, since we're posting back and forth vs talking on the phone (real time), I would remove 10% fuel from about 200kpa on up and around 5% from 150kpa up to 200

Thank you, I'll take another look at my latest log once I get back in town and double check to make sure those changes line up with my readings and see where it lands me at. Thanks again Cal!


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