MAF Scaling - Open/Closed Loop Fueling info

[s2d4]

Originally Posted by solidONE

It looks like the computer makes too much compensation for temps in the base fueling causing the AFR to go rich in lower temps but lean in hotter temps. Once the AFR registers fueling adjustment is made via fuel trims.

Bleh, brain fade moment of not realising increasing fuel trim because it is running lean. Have you tried changing the temp compensations?

[solidONE]

Originally Posted by s2d4

Bleh, brain fade moment of not realising increasing fuel trim because it is running lean. Have you tried changing the temp compensations?

Not yet. I only discovered this recently, so I'm just going to keep this in mind while I continue to dial in the maf scale. I'd want the fuel trims to be a bit in the + side on hot days and a little in the - end in cooler night temps across the board aside from idle. Since idling IAT's tend to be high even when IAT's while the car is moving are on the cooler side. Once I have the MAF scale to where I like it I'll start to mess with the temp compensation. Just curious if anyone has done anything about it. Also if you didn't know that there was this variation in fuel trims due to temperature change you'd never be able to get your MAF dialed in and chasing your tail until you realize this.

[Kodename47]

Originally Posted by solidONE

Not yet. I only discovered this recently, so I'm just going to keep this in mind while I continue to dial in the maf scale. I'd want the fuel trims to be a bit in the + side on hot days and a little in the - end in cooler night temps across the board aside from idle. Since idling IAT's tend to be high even when IAT's while the car is moving are on the cooler side. Once I have the MAF scale to where I like it I'll start to mess with the temp compensation. Just curious if anyone has done anything about it. Also if you didn't know that there was this variation in fuel trims due to temperature change you'd never be able to get your MAF dialed in and chasing your tail until you realize this.

The simple solution is to zero out the IAT compensation table while scaling the MAF. You should really do that to all compensation tables while calibrating for that very reason.

On ECUtek you fill the table with values of 1, RR is 0.

The IAT compensation isn't a simple hot/cold +/- as it reverses as air volume increases too. I would return the stock table when you've done calibration.

[jamesm]

Originally Posted by steve99

Yes noticed similar mostly at idle where iat climhs in traffic fuel trim in lower band moves 4 to5 percent however need to look at if the temp comp is for sensor error at differnt temps or ita actually to compensate for the density change in the air.

the sensor is trying to measure mass of air colder air more dense so it most likely needs to add fuel so moves fuel trim positive.

not sure will have to think about it

This is very important... And why it's crucial that you filter out high IATs when doing the calibration.

[solidONE]

Originally Posted by Kodename47

The simple solution is to zero out the IAT compensation table while scaling the MAF. You should really do that to all compensation tables while calibrating for that very reason.

On ECUtek you fill the table with values of 1, RR is 0.

The IAT compensation isn't a simple hot/cold +/- as it reverses as air volume increases too. I would return the stock table when you've done calibration.

I havent touched the temp compensation table. Unless Vishnu Tuning changed it from stock values, I dont think it has been changed.

[ML]

Well I've done a couple set of CL and OL logs, and input them into vgi's tool (thanks btw for that). and one thing I noticed is my CL corrected MAF scale has hardly any corrections, maybe two points that are barely off. But when I do OL and there are a lot of corrections, and the corrections are mainly in the middle of MAF scale curve where as the CL corrections are only at the beginning and the end. My question is should I be combining the cl/ol corrections together? Also does this sound normal?

[steve99]

Originally Posted by ML

Well I've done a couple set of CL and OL logs, and input them into vgi's tool (thanks btw for that). and one thing I noticed is my CL corrected MAF scale has hardly any corrections, maybe two points that are barely off. But when I do OL and there are a lot of corrections, and the corrections are mainly in the middle of MAF scale curve where as the CL corrections are only at the beginning and the end. My question is should I be combining the cl/ol corrections together? Also does this sound normal?

Yes sounds normal.

might be worth just applying the CL corrections, then check the OL again after that. Yes sometimes you have to average them.

The CL corrections should be somewhere around what your LTFT are the OL corrections will be the difference between the AFR measured and AFR commanded (in OL fuel tables).

Make sure you do the logs at similar temperatures, wide temp variations will cause problems. If you could do them around 20-25 C this is ideal as that is where their is no temp compensations applied not always possible though.

[ML]

Thanks, I have been using Airboy's spreadsheet to find my AFR error %, what are you using for that? And unfortunately I have been doing all my logging after work when its about 32C, so maybe I should redo everything in the morning. After I get the MAF scale down is it worth looking at injector scaling with stock fuel system?

[steve99]

Originally Posted by ML

Thanks, I have been using Airboy's spreadsheet to find my AFR error %, what are you using for that? And unfortunately I have been doing all my logging after work when its about 32C, so maybe I should redo everything in the morning. After I get the MAF scale down is it worth looking at injector scaling with stock fuel system?

Initially I used the "Yikes" spreadsheet for CL scaling and just calculated the OL manually.

When VGI utility came out re-did some more logs and just imported them into his utility (tactrix logs) with the OL fuel tables and MAF values , in less than 5 minutes it did what took hours and came up with same results.
now I'd just use vgi utility for both ol/cl its magic.

As long as you do logs at same temps it should be fine, just not some at 10c and others at 30c for the one calculation.

[Kodename47]

Can I point out that to ensure you add the max/min correction % into the OL section. You will always get a big error shortly after the throttle opens and you do not want this to be used for corrections. The tool is set to 200% by default, what I'd do is load in the log like that, look at the data at the top of the columns and have a quick check over what seems a good limit to set. Clear the run data and load in the same log with the limit set to a sensible value, I usually shoot for 7.5-10%. That should help with the lump you get around 3v.

I also set OL min and CL max to 3v.

[Kodename47]

Seeing as this is most relevant thread I thought I'd add this here. For those that have been wondering how to do the PI/DI scaling. This is a spreadsheet tool I've put together:
https://dl.dropboxusercontent.com/u/...libration.xlsx


If you have any form of MAF scaled maps, use that to create 2 identical maps. 1 with 100% PI and the other with 0% PI, although I leave the standard ratio above 5200. Go and log data on each as if you were doing CL scaling.


On my tool, input the MAF scale and use this for @vgi's tool as well. Then copy the corrected MAF scale (only the g/s with no smoothing) into my spreadsheet for both DI and PI results into the New PI/DI columns and voila....


As the MAF tool adjusts all values below the lowest recorded MAFv by the same correction factor, I find it's best to remove any duplicate error values in the low RPM range. Then use the % difference chart to work out where to set the max and min range as to avoid erroneous data having an impact on the injector scalar. You then can select which injector set to adjust if necessary. I would choose the range with the most positive trims/error, or whichever is the higher line on the graph. I would always look for the ideal correction to be at the higher voltage range as at lower voltage the PI system can have latency error as well. This will become obvious if the lines drift apart or get closer the nearer you get to 0v.


I've also included a couple of columns for you to paste the DI fuel rail pressure for any adjustments you may want to make later.


The last 2 tabs are for you to keep an eye on how much MAF variation your map has from the OEM map. This will allow you to see if there are other issues, like if you're bumping up the whole curve etc. Paste your MAFv range into the OEM adjusted column and it will calculate the correct g/s. Then paste your current scale into the current ROM columns.


Any questions then please ask.

[Turdinator]

I just went and took a nice hour long log to start scaling my MAF and then went to use Vgi's java app only to find I didn't log RPM. It might be worth noting that in the first post under procedure @steve99
It was stupid of me but I literally just logged what you had listed.

Also can someone confirm what does OFT call the commanded AFR? Is it Equivalence RC?

[steve99]

Originally Posted by Turdinator

I just went and took a nice hour long log to start scaling my MAF and then went to use Vgi's java app only to find I didn't log RPM. It might be worth noting that in the first post under procedure @steve99
It was stupid of me but I literally just logged what you had listed.

Also can someone confirm what does OFT call the commanded AFR? Is it Equivalence RC?

If you oft is calling it equlivance ration you need to opdate the oft and template file make sure your open flash manager is 1.07.1 as well

[Turdinator]

Originally Posted by steve99

If you oft is calling it equlivance ration you need to opdate the oft and template file make sure your open flash manager is 1.07.1 as well

I updated to OFM 1.08.0 last night and then did my log today. Could it be it just hasn't been updated on the 700G roms? Or do I need to download something extra?