How to tune lowest load row in VE Table?
 

Gents,

MLV wants me to put in a sh!t ton of fuel in the 20 kPa row, 25% more in places than in the 30 kPa row when I analyze a track log. However, when I scroll through the log, those settings produce ridiculously low AFRs. What's the general rule of thumb for tuning that lowest row for the track?

Thanks,

are you talking about the bottom most decel row? If so, that can be leaned out as it's vacuum. I go 15-16:1 on my car for daily driving however i've read of some people going as lean as 18:1.

You can also activate over run fuel cut. As the name implies this cuts all fuel on decel/vacuum and essentially turns the injectors off.

I'm sure the pro's will chime in with much better answer than I.

I'm still a total noob when it comes to tuning, but I found I would get some bucking transitioning back to throttle from decel on the track, and adding fuel in those low kPa cells smoothed things out.

I would pay more attention to the behavior on the track than the absolute numbers, as long as they're not ridiculous.

Problem is, they are ridiculous. I had guy one tell me I was shooting flames out the exhaust on downshifts. No one ever said that before, but I see it a lot on other cars. Good thing the cat is gutted.

I do have ORFC active, but the transition during shifts is not long enough to have it come on.

I have 14.7 in the bottom row now, but I was seeing 9s when reviewing the log and I was still way short of what MLV wanted. For example, for the 4800 rpm, 20 kPa box, it wanted 125. I put in 100 as an experiment--I think I had 80 in there before--and still saw really low AFRs between shifts.

I assume then, there's no actual reason MLV is suggesting these numbers and I should go back to something a little lower than the 30 kPa box above for each?

Thanks,

Just linearly extrapolate VE numbers from the next 2 rows. Take a log and see if it's reasonable. Self tune if MLV isn't giving useful results.

you never tune the bottom row with ve autotune.

you always set the lower kpa threshold for autotune to something like 40-45kpa, then dial it in by hand. just like you never should tune idle with autotune.

You can pull tons of fuel out of there. In the same way that the car doesnt have trouble getting going again after over run fuel cut, it wont have any trouble going from a tiny bit of fuel in super high vacuum back into cruise or higher load cells.

No autotuning going on. MLV just consistently was telling me to add fuel there when I analyzed a track log, and I tried it. Before I had been using a little less in each box than the one above it, but there was no "method" involved.

Mlv is megalogviewer. It doesn’t tell you anything. Ut shows you your logs.
What do you mean by “telling me”

I open my logs with MLV. When I run VE Analyze within MLV, it gives me suggested fuel numbers. Those numbers are gynormous for the lowest load row at the track rpms, say above 3900 in my VE table. Isn't that how it all works?

lol you tune your car, not let some random number generator tell you how to do it. just like people should never use the "map generator" function.
I bet mlv doesn't account for overrun and is trying to compensate

That's how I do it. When you open the VE Analyze window there are options to filter the analysis. Filter anything below ~30kpa and below 1200rpms. You can go more or less aggressive with the filters to find what works best for you.

You also want to watch higher rpm, low load cells. Those +4000rpm cells below 100kpa always want to lean out really bad for me, as a result of data collected between shifts I believe. If I let MLV do what it wants when I do end up cruising pretty quick on the highway it'll be super lean.

That makes a lot of sense.

I look over the suggested numbers from the MLV analysis and make my own decisions. I think it would be difficult to do it any other way with just one person since I don't like what I get from VEAL.

Thanks,

Something that might help is to use the 3D view. I used it to get my bottom row close, just by making it a “smoothed landscape” based on the rows above. After that, I fine-tuned via MLV and watching the gauge.