Maf Hz reading maxxed out, what to do?

[lateshow]

We have now reached a point where the logged Maf Hz (request 1A) is 1593 Hz which is 255 multiplied by 6.25. Ecuload doesn't seem to rise at all after that point . It seems to maxx out at 5500 rpm and 250 and after that point Maf Hz is maxxed out

This either tells us

1. Vr4 MAF is maxxed out?
2. There is actually a second byte for Maf Hz somewhere ? like for ecuload?
3. Maf can be rescaled for greater flow?


We have now two cars with td04 turbos. 13t and 19t. They both share identical ecuload diagrams. They both share the same max IDC and same mixture. BUT the car with 19t has bigger injectors...

[Confused]

airflow2byte.PNG

[lateshow]

Will this request work on Kenneths rom (which our final mod is based on)????

[lateshow]

Already tried that and wouldnt work...gives strange values :/

[Kenneth]

2 byte load and 2 byte RPM should be 00 and 02 respectively.

The 4 bytes in the MUT table should be 0xF0CE, 0xF0CF, 0xF0A8, 0xF0A9
For the 2 byte MAF, try 0xF0D2, 0xF0D3

[lateshow]

2 byte load and 2 byte RPM should be 00 and 02 respectively.

The 4 bytes in the MUT table should be 0xF0CE, 0xF0CF, 0xF0A8, 0xF0A9
For the 2 byte MAF, try 0xF0D2, 0xF0D3

The following I have now MUT00=F0D8 MUT01=F0D9 MUT02= F0A8 MUT03=F0A9 MUT04=F225 MUT 05=F245....2byte load from MUT00 and 01 seems to work with that combo.
If I understood correctly I should put MUT04=F0D2 MUT05=F0D3 and 2byte airflow should work with standard request and standard scaling?

Greatly appreciated!

[Davezj]

I need to measure mass air flow in some kind of units other than Hz. To be able to calculate the actual volumetric efficiency of my engine.
Is there a conversion from Hz to grams/second or lb/minute or m3/second or something like that.

I am using the actual mass air flow/theoretical mass air flow
To calculate VE

I just need to be able to measure the actual air flow.

If the 2 byte mass air flow mod works then i will implement this in my MUT table.

Thanks for any help given


Sent from my space-aged gizmo

[Kenneth]

0xF0D8 seems to be more closely linked to MAF frequency than calculated load. Its really up to you, but 0xF0CE is the compensated load which is used for fuel, ignition and boost control.

You might find that 0xF0D2 fairly closely matches 0xF0D8. I haven't looked at it closely enough to determine which does what, but there are a number of places where they are both set to the same value.

It might work with the default scaling. I would have to disassemble the Evo ROM to check if its effectively the same variable. The thing you need to realise is there are MANY variables used in different parts of the firmware, while they look to be very similar, there are variations based on compensations, logic decisions and other hard to determine factors. Whether one or another is the "correct" one is really hard to determine. In the case of Load, its a bit easier because load is directly used for fuel and timing lookups.
In the case of airflow, what do you mean? There is raw MAF Frequency, then it is scaled numerous times based on various compensations (IAT, Baro, MAF Scaling, injectorScaling etc).
0xF0D2 is used in the same function as the Load calculation, so its probably reliable.

[Kenneth]

There was a spreadsheet developed, but the site that had the instructions for it (geekmapped.com) seems to be down.
You need to log a few parameters, I think RPM, load and MAP (you need the MAP sensor installed and connected to the rear O2 input).

I have the spreadsheet still, but no idea how it works
Attached here:
http://www.clubvr4.com/forum/attachm...chmentid=75670

I need to measure mass air flow in some kind of units other than Hz. To be able to calculate the actual volumetric efficiency of my engine.
Is there a conversion from Hz to grams/second or lb/minute or m3/second or something like that.

I am using the actual mass air flow/theoretical mass air flow
To calculate VE

I just need to be able to measure the actual air flow.

If the 2 byte mass air flow mod works then i will implement this in my MUT table.

Thanks for any help given


Sent from my space-aged gizmo

[Davezj]

Thanks Kenneth that is interesting spread sheet I will look at it at lunch time on my PC rather than my phone.
Thanks again


Sent from my space-aged gizmo

[Davezj]

As i said above looks interesting but it is just a bunch of numbers, no offence meant to you kenneth i know you are only posting something you though might be useful.

Having looked at the spread sheet a bit more closely.

there is no info about where the VE data came from.

was it a modified car (had inlet or head work done or stock) what car the info is for.

Map value in what units, it looks like load% similar to the timing and fuel maps to me but i can't be sure. MAP would be in psi or bar surely.

It looks like the spread sheet has been developed to show on a given power run what the volumetric efficiency is through the rev range. where the numbers come from who knows.

I suppose if you did multiple power runs at different boost levels and hence load% values you could get a general trend for where your engines sweet spot is for VE and target that area for the boost to be in when at WOT.
I suppose it could help you pick a boost pressure and hence pressure ratio to aim for when choosing a compressor wheel from a compressor map. you would want you boost pressure to be in the highest VE area of the table and the resulting PR to be in the middle of the highest efficiency island of the compressor map.

[c0xxy]

If it's the spreadsheet I'm thinking of, you need to fit a map sensor to 2nd o2 sensor input on ecu n log that with evoscan to fill in the map values. When all the values are in, you press the button and it calculates ve for you

sent from ash

[Kenneth]

The spreadsheet was developed specifically for going from MAF to MAP in Evos. The pressure is kPa, which is Bar / 100.
Anyway, this is the wrong thread for this discussion. Start a new thread please, or PM me a link to an existing one.

[Davezj]

yes i have the map senor fitted to rear O2 pin on ecu and i can monitor it on request 3C in evoscan.

kenneth the MAP sensor is saying the boost pressure is 2.6 bar, is that 1 bar atmospheric + 1.3 bar boost or 2.6 bar of boost.

OK i understand what you are saying about starting a new thread.

here is a link to a thread i started a few days ago about the VE of a 6A13tt.

http://www.clubvr4.com/forum/showthr...ric+efficiency

[Joe90]

Use a frequency counter hooked up to the AFM wire, you can read the Hz independent of the datalogger. You should see over 2KHz before the injectors are maxed out.

[lateshow]

Back to subject:
0xF0CE is truly the right address for compensated load. Now it would be very nice to know if 0xF0D2 was actually the the non compensated load. 0xF0D8 could be Maf Hz but seems that evoscan function should be changed? Does anyone have any idea. It was about 10 times too small compared to the actual maf Hz. This was using the stock 2byte maf function in evoscan.

It seems rather strange that my car has been proven to have about 450 horsepower from the crank and still compensated load is about 200 all the way to up there.

I will propably take the car back to dyno this week. Seems to be some issues, maybe the engine is finally dying.

[lateshow]

I still think that F0D2 and F0D8 can't be MAF Hz readings since they seem to form a same kind of plot as load compensated.

2byte load (if I read address F0D2) is just higher than compensated after a certain load.

[lateshow]

More info:

FD02 and FD03 are master loads...at least in my case. 2-byte airflow is F0FC&F0FD
2-byte load uncomp F0C8&F0C9

My rom is originally Kenneth's 1.03 with our own flexifuel mods and maybe SD in the (not so distant)future....

Standard vr4 reaches about 1100-1300 Hz, mine reaches nearly 2200 Hz. There is a point at 5500 where the maf Hz doesn't rise so quickly anymore. But still it rises all the way to the redline.