Maf Scaling VGI Tool
 

Hey guys!

I'd like to get into MAF scaling, as I'm still getting a bit of knock. I pulled a good amount of timing in some areas (~1.76 degs) on my tables, but I'm still getting knock. I believe this is due to the inconsistencies with fueling, mainly LTFT%/STFT% fluctuating too much. From what I've seen good MAF scaling can yield +/-2% fluctuation.

Basically whats happening is for a week or so I'll get good results from pulling timing in my tables, then a couple days later I'm seeing more timing pulled (IAM slowly dropping). I believe this is mainly due to changes in fueling, I understand that there are other parameters (temperature, altitude etc.) but this seems like the easiest one to control.

So what I'm really looking for is a good guide on how to use VGIs tool, not really understanding how it works or how to load the logs into the tool. I couldn't really find any videos, or good threads will lots of pictures explaining whats going on, even read the wiki a bit. Any other tips are appreciated.

I've read a pretty good portion of this thread so far... http://www.ft86club.com/forums/showthread.php?t=64790

Its probably also important to note, I have a butt load of datalogs.

OFT? If so remove the 1st few lines of the log in excel or similar so the top row is your data headers.

The tool will allow multiple logs to be loaded at once, this is beneficial if you have them. Once you load the 1st log, just click load log again and select another. It adds to the data imported.

For CL I'd then look for your longest 3 or so logs so that you have 30-60 mins of CL driving.

What are you struggling with or don't understand?

Well that certainly helps, I think I just need to keep reading more and I'll understand. I just have some questions :P

I'm a OFT user and I didn't know about the bit with removing the first few lines, that would explain why when I clicked "load log" the headers weren't being properly populated.

So for closed loop, is it pretty much normal everyday driving? Light on the throttle shifting under 4k RPM? As far as I know it only goes into open loop with quick throttle movements and full throttle. So do you want to do a CL log where you slowly redline it or would that not be beneficial?

The other thing I wasn't sure of is, how does the tool work and the idea behind MAF scaling? Is the premise of MAF scaling to have the AFR more closely match the command AFR? If so, how does the tool correct the fuel trims?

For closed loop you want minimal throttle changes but you want to cover as wide of range of voltages as possible, there's no real max RPM however the ECU will switch to OL at set throttle angles so just keep an eye on the tablet The dV/dt setting will remove large changes of throttle. For best results you really want flat road and to almost hold the engine at an RPM. Realistically that's not always possible so the more data you get the more reliable the results. Here's why....

How it works:
Closed loop operation is where it uses feedback from the O2 sensor to hit it's AFR target. On this ECU it's between14.7:1 and 14:1 as standard. The base calculation is done from the MAF, and then adds trims as a result if the fuel mixture is rich or lean. The fuel trims are a percent of added fuel, but can be described as fueling error. If you average out the trims for a given MAFv then this will give you the change required to the g/s value, hence why the more data you have the better result you get.

An example:
@2v the scale shows 35g/s
At that voltage the average fuel trim is +5% meaning that the g/s value makes it run lean and the ECU is adding fuel to compensate. Just for illustration, the STFT max/min could still be -10 to +15.
So we need to increase the g/s value so that the ECU will add more fuel, so if you increase it by 5% then the average error should now be 0%.

Ok, so would going for a freeway cruise and start logging when I get on the freeway make for a good CL log if theres no traffic? From what youre saying you get the best results from just cruising at a constant rate of speed? Flat road is unimaginably hard to achieve so there will be throttle changes, no way around it.

Thanks for the explanation & example on closed loop operation. It makes sense, I just wish my logs would let me take a look in the tool lol.

I'm getting this error, I know I have to change a couple parameters that I'm logging but I was just testing to see if it lets me load the parameters into the tool. This is what I'm seeing after I delete the first 3 rows in the OFT log spreadsheet. Before it was just saying "Procede Data Log" which is the first row in the excel spreadsheet. Hrrm...

http://i.imgur.com/20DpGRc.jpg

are they saved as a .csv format?

Excel likes to resave files as .xlsx unless you force it to save as .csv. VGI's tool only reads .csv files, make sure you're saving as that.

^got beat to that one haha

Thanks gents, its working now.

So I just did a log on the freeway for about 20-30minutes just to throw it in the tool to see how it works. I followed the wiki & that helped a lot, it pretty much does all the work for yah I guess I didn't look hard enough.

The only thing I don't get is whats the point of recording...

30 minutes of general driving
15 minutes of slow speed driving
^ I assume these should be with no sudden throttle changes either

Is the purpose to get a nice spread of different MAFv & g/s?

Yes. Obviously big sudden changes of throttle aren't ideal however so long as they aren't frequent then it's not an issue. I generally have done mine on UK roads in traffic etc. If you reduce the dV/dt value then this will reduce the data from large throttle angle changes but in doing so will obviously reduce the data that can be used. You need to find a fine line and trialing different settings.

I have a general rule on my car.
20 mins or less - dV/dt=0.55
30 mins - 0.5
45 mins - 0.4
60 mins - 0.3
You could use values inbetween etc.

Also try and keep the intake temperatures constant. On the graph screen you can view IATs of the imported data, I would then look to ensure that the spread is minimal (~10C.... I don't do Fahrenheit). You could then go back and reload the data and to trim down the IATs range.

Hi @Kodename47,
about the section of speed density VE tablez i m not able to create a sd table using ecutek logs and data
have you ever tried doing it and if yes do you have suggestions on how to use it?
thanks

I would just use the Log Stats tab. Here's some formulas you can add to your log if you use the EVI to get there. Just copy and paste into the header row.

Non-EVI EcuTek:

sorry i do not understand.. i tried put that into my racerom10 k00g logs
and i don t understand what i have to do in log stats


i wanted to use the MAF VE calc tab to receive a VE table from my logs but all i get is errors and can't even paste my current ve table into the tool
also, SD Cobb or RR for ecutek logs?
MP torr or psi since i have it in bar?

Could be unrelated but I would highly suggest to calculate/visualize your total ignition (base timing b + kca) and look out for rough or unproportional steps.


The engine will benefit from a good, smooth map. Visible knock correction in the log does often not display where the event really occured. It could probably be a result of an adjacent cell and a subsequent faulty approximation of the ecu.


Excuse my bad English.