ITBs and a MAF sensor

[irishtwincam]

Ok,

Normally aspirated 4AGE on ITBs, mild cams.
Currently mapped on AlphaN 0-8500rpm.
Pressure correction DOES NOT seem to work since successive street runs between motorway intersections
into a head wind/with following wind, whos varying air fuel ratios.

Example of problem:
East to west, tune for stoich
West to east, runs lean, retune for stoich, (headwind = supercharging)
East to west, runs rich, retune for stoich (tailwind so we run rich)
West to east, runs lean. (headwind again)
Cycle repeats.
Barometric correction in engine bay not working.

Would using a MAF sensor allow one to distinguish load between 25 and 100% throttle?
With MAP and AlphaN/SDblending, 25% throttle and 100% throttle both read 100kpa so tuning is impossible.
And as mentioned, the supercharging effects of driving at speed arent being factored by VEMS?

Update: VEMS DOES NOT SUPORT MAF SENSORS:
Is MAF the solution?
Surely 25% throttle will less air than 100% throttle?
Can vems run AlphaN with MAF correction or something?
At speed the increased airflow WOULD be detected by the MAF fixing this east-west-east pressure/airflow issue.

Would using velocity stack into the pressure sensor work?

Another idea:
Map engine on a dyno for AlphaN only.
With no massive 100mph airflow (except cooling fans) we would get a fuel table and spark table for when the engine is underload without high speed supercharging effects.
Remap the car on the road and we will get, I suspect, same fuelling but different spark and lamda.

Can the differences in ve/spark and lambda table be used to improve VEMS algorithms to support corrections?
Note: Speed would be a cheating way of doing this as it would be a related to the pressure increase.
If we are at speed on an oval circuit or between motorway junctions, the pressure IS different!


Another symptom of the alpha N limitation is that on a dyno the car runs INCREDIBLY rich since there
is no increased airflow as when is was street mapped, so no idea of what power the car is making :-(

[gunni]

Baro in the intake trumpets used a pressure correction and you should be good.

using the latest firmware you can adjust the MAP scale to be only from 90-120kpa
And thus below that sort of pressure in the trumpets you´ll run alpha-n * baro correction

Cause baro/ram air correction done right will work..

[irishtwincam]

So put map sensor pipe NEAR the ITB intake?

or

Put map sensor pipe into side of the velocity stack of the ITB?

Can you illustrate with a picture please?

[gunni]

You´ll have to measure the pressure inside the trumpet.
so above the throttle plate.

[irishtwincam]

I understand.

So if this is done, there should be no variation in air/fuel ratio on the dyno or travelling in different directions between motorway juntions?

[gunni]

If you set things up right then yes there will be no variation as you´ll be compensating for ram air effect.

How big of a variation are you seeing now in the mixture?

Also you might want to use a pitot tube in the trumpet angled outwards to get accurate readings of higher pressure due to vehicle direction and speed(i.e ram air effect compensation)

EDIT.
Just to point out I´m not 100% sure on if the application of a simple pitot tube into a pressure gauge would be adequte.
But I´d personally be into finding out

EDIT again.

http://www.texense.com/?p=espace&produit=32&espace=1&lang=uk
http://www.engineeringtoolbox.com/pitot-tubes-d_612.html

[Sprocket]

The pitot tube i think would work.

The Austin Metro Turbo used the age old SU HIF44 carb. The plenum had a restrictor that generated a slight pressure drop in the carb producing a pump effect on the fuel jet. Some one built a new plenum but never realised this. after seeking advice, he installed a pitot tube in the plenum to replicate the same function, and it worked a treat.