I'd like to know how the MAF actually works - how is it estimating the data? Anyone know where to get any info on this very dull subject?

 

I suspect the poor MAF would at best misread and at worst fail if you removed the mesh- it would make it very susceptible to damage. The hot wire MAFs work by heating a wire and seeing how much it is cooled. Not sure about the hot film.

The STi inlet temp probe is interesting, but there is a boost pressure compensation map using it which is full of $80 everywhere - ie does nothing. I am not aware of it being used otherwise.

 

Ah, OK, the MAF isn't actually a very clever bit of kit then Faster moving air - but a lower volume - would actually be seen as a higher volume (and so produce a higher voltage). I can see room for error here...
Anyone know what the flow pattern is like from the standard filter malarchy? I'm guessing here that it's rather centre-orientated - the spread throughout the cylinder isn't very good (basically behaves as if a heavy boundary effect), and the MAF is calibrated for this. When a bit of kit comes along that is designed to fill the tube (rather than the just the middle section of it) with moving air (in other words simply creating a better/more efficient flow), there is better flow 'cos the whole diameter of the tube is used (rather than just increasing the flow around the MAF). So the actual velocity of air is slower to produce the same volume relative to the resonator doobrie, hence the MAF underreads.
Which everyone probably knew already. So sorry for the waffle.
Anyway - the quest is to find a way of accelerating the airflow in the small area just in front of the MAF.
Or just reprogram the ECU, which would probably be a lot easier

 

There is a tool in the EcuTek Delta ECU software where the MAF can be calibrated. Probably for our application Nom. I don't think the tuners have played with this feature yet, but it looks like Merv will be giving it a go soon.

As for the log comparos, I believe my injector duty cycle coincides with Nom's for the airflow and boost I was running for that log. I usually run 17 psi, but have lowered it ever since I found that my 02 sensor readings were lowish. So I too can confidently say that the APS kit is the cause. It is a top piece of kit though and can be sorted with a map.

Cheers,

Wrexy.

[Edited by WREXY - 7/15/2002 2:35:55 PM]

 

Yep, agree with everything there
The two maps could be, well, peas. In a pod, that is.
As similar as.

Yes, I think I should go now as well, but I can't for another couple of hours

 

I may play with the MAF calibration if I run out of MAF signal - at present it saturates possibly a bit early but this can be changed in the table.

 

John - at what voltage does it give up?

Richard

 

I posted the table in another thread - if you can find it you will see. I think it was one of WREXY's lean threads. If not I will look later on.

 

The MAF scaling table is here.

http://www.scoobynet.co.uk/bbs/threa...hreadID=102042

Cheers,

Wrexy.

 

4.64V then but it can be altered - I guess I will be in the 4.5 to 4.6 range when done whilst presently in the 4.4 to 4.5 range.

 

Cool, thanks all. Two weeks to go, then maybe I'll stop asking stupid questions....maybe

Richard