Speed Pro VE Overlay/Correction in Closed Loop?


New Member
I saw this on the Corral:

"One of the most difficult parts is trying to predict your VE at different RPM and boost points. One thing that really helps, mostly for street tuning, is the letter "L" key on your laptop. You can drive all around and have someone hold down the "L" key and the computer will automatically overlay the correct VE numbers in the cells effected by looking at your predicted A/F ratio cells and your wide band O2 readings. "

I'm a rookie here and I didn't see anything about this in the documentation. I take it this would only work while directly connected to the ECU. Do you have the VE table open when pressing 'L'? What's the proper procedure? Looks a very helpful feature!



I too am very interested with this answer. I bought a car with the sefi8lo system on it already. Supposedly tuned by ANS. The car was pinging while on boost. I have rid it of that and have a decent A/F ratio while cruising, but at 3896rpm and 195 kpa the A/F ratio is way rich 9.19 to 1, injector dc is 49.5, and O2 correction is 0%. Like Blown98Rt I think my VE map is way off but not sure where to change it to. I am new to this system and the turbo cars in general as I have only owned the car a week. I just bought the lap top last night and started working out the pinging on the way home from work.

Craig Smith

That was easy!
Many people who know of the "L" key think it is more powerful than it really is, so I'll take this opportunity to explain what it does.

Pressing the L key while online with the VE table open will apply the current O2 sensor correction to the cell you are currently operating in. So, if you see the blue oval floating over a cell and the ECU is reporting 10% O2 correction, when you press the L key, the ECU will add 10% to the value in that cell. At that point, you should see the O2 correction approach zero. It works well for steady state tuning, one cell at a time.

I won't sugar coat this because I want everyone to be clear on it - simply having someone hammering on the L key while driving is a very bad idea and you are asking for trouble if you do it. As the blue oval travels through a range of cells, even the transition from a cell of high value to low value can cause the O2 correction to go sky-high while at that instant, it is in a perfectly calibrated cell. Rich or lean spikes associated with quick changes in throttle position or manifold pressure can also produce the same result. By just leaning on the L key, you could be applying corrections that may be skewed by a rich or lean spike. The results may just be a bad tuneup, but it could prove fatal to your pistons. Why take that chance?

The L key is a cool thing if you know exactly what it is, and what it will or will not do. I just want to make sure that everyone who reads this is clear on what it does.




New Member
Thanks for the clarification Craig. Do you care if post your message in it's entirity to to the Corral? Would like to prevent others from making a mistake!