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REFERENCE: VE Table Comparison Stock vs. Modified: Why Tuning Matters

KANE

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Mar 2, 2002
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Dark Blue 1982 Trans Am(s): Polo Green 1995 MN6
VE stands for volumetric efficiency. Maximum VE follows right after peak torque... and the VE table is the base document to tell the ECM what to do for fueling. Everything else that happens is a modifier to that base document. Cold outside? Add to the VE table through multipliers. Still not the right commanded AFR as reported by the O2 sensor? Add to the VE table through multipliers. The VE table is critical.

The stock CFI engine cranks out 285lbs-ft of torque at 2,800rpm. So, we would expect the highest VE to occur just after that point- which would be at 3k rpm on the VE table. The image below shows what this would look like and was the base VE table for my previous combination (stock TBs, Renegade, 65lb injectors, 14.5psi, Comp Cams Computer cam .425"IN/ .440"EX). No VE tables are available to the best of my knowledge for either the 82 or 84 CFI ECMs, so I had to come up with my own.

My .465"IN / .488"EX cam is a bit of a departure from stock... so tuning is required. The engine I have hits peak torque much higher than stock- at 3,800rpm. So peak VE hits at 4k on the VE table.

Attached is a comparison of VE tables.

To get the tune from the bottom table to the top table... takes tuning. The stock ECM can't make changes that big all on its own. It needs an intervention- which is tuning.
 

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  • VE compare.jpg
    VE compare.jpg
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