Back to basics... VE tuning

[ferocity02]

Last week I installed an aftermarket fuel pressure regulator that is vacuum referenced like stock. I also used it to lower my base fuel pressure to 48 psi to make my injectors "smaller" since they are a little oversized for the amount of boost I'm running now. I re-scaled the IFR table and decided to retune the VE table.

I've tuned the VE table before but was never very happy with it. It always comes out really bumpy, had some odd trends here and there. The low MAP cells are driving towards zero due to a rich decel issue, which may be due to bad injector data. I think the voltage offset table is adding to much pulsewidth so it's hitting a minimum value around 1.7ms, even with all of the min pulsewidth setting set to zero, including B9021.

I've been using solely my wideband to create the BEN/correction factors, with the following equation:

BEN = (Commanded EQR) * (Wideband lambda)

I've adjusted the VE table at least 100 times now to the point where its not recognizable, and would like to start fresh with the stock VE table and retune from there.

My question is, should I use the STFT's to tune stoich cells and wideband for enriched cells, or use the wideband for all cells? I've been told that since the NBO2's are more sensitive to stoich that they should be used to tune any cells that are commanded stoich. Wideband is obviously required for non-stoich cells.

I am running COS5 speed density, LS1B PCM, vehicle in sig. Thanks!

[statesman]

I would suggest trying to get your fueling tables sorted out first, then do your VE tuning.

[joecar]

There will always be some small amount of trim, and VE table will always have some ripple...

you can do both separately (wideband only, or STFT) and compare the results.

post screenshots of your VE and of a map of trims.

[ferocity02]

Thanks guys. I definitely want to fix the injector issue first, but unfortunately I'm using the data as it was sent to me. I am hesitant to go and start modding the injector data because then nothing else in the tune will be realistic. Or am I overthinking it? If I drop the voltage offset then it should fix the issue with it being super rich on decel.

Either I have to find the correct data for these injectors or get new injectors with reliable data. My current injectors are Bosch 60lb/hr from Fuel Injector Connection. The voltage offset at 14V is 1.03ms which is high compared to other similar injectors. These are the ones I have: http://fuelinjectorconnection.com/sh...p?productid=25


If I were to use the NBO2 STFT's to correct the VE table, would the BEN be as follows?

BEN = (STFT1 + STFT2) / 2

I have LTFT's disabled at the moment.

[joecar]

The BEN would be (STFT1 + STFT2)/2/100 + 1 to make it a multiplier .

[statesman]

If I drop the voltage offset then it should fix the issue with it being super rich on decel.

It might fix the issue but I don't think it's the right way to do it. You were given the voltage offset data for those injectors so you have to assume that it's right. You said that you hit a minimum pulse of around 1.7ms and your voltage offset is 1.03ms, so there's nearly 0.7ms of pulse coming from somewhere else. I think you should try to find where that extra 0.7ms is coming from before making arbitrary changes to a table which you have data for.

If you can post your tune, maybe somebody will be able to spot what's causing this.