J Chen

Has anyone taken voltage measurements of the
MAF at idle, 2000 rpm, 3000 rpm & so forth ?
Can you share your findings ?

Thank you.

RKD in OKC

Idle is going to be the same, but at any other RPM is really is a matter of whether you are cruizing or accelerating, on boost or off.

My idle is around 1.23 to 1.3 at 1000 rpm.

fast951

The voltage depends on the MAF calibration even at idle.

Tom M'Guinn

I've never measured the raw MAF signal, but have monitored the conditioned input going to the DME pin 7. Seems like lots of variables affect the signal needed there -- chips, O2 feedback, injectors, air temps, etc. I've had my car idle well as low as .2 volts and as high as .8 volts.

daniel951

mine read as high as 1.7 at idle

awilson40

Thats a heck of a diff over the stock. Mine is .6 v at idle on the Zeitronics
No wonder you need custom chips or a signal massager

J Chen

Thanks guys, yes I know that even the setting of
of the TB will affect the readings at idle. Now if
we were to collect voltage readings for every 500
rpm increment of a specific MAF combo, will a tuner
be able to use this data to mapped a chip that performs
spot on & only needing a little fine tuning there after ?

Sam Lin

It's very inaccurate to use on-engine measurements for this since it's a crapshoot of factors. What you're talking about is building a voltage table for a given MAF - this is very common, all of my MAFs come with charts. If you're reverse engineering, then you need to use a flow bench. Chart X flow vs Y voltage, and you've got something that any tuner can then use to map accurately.

Sam

Lorenfb

The output voltage from a MAF or AFM (0-5 volts) is a function of engine load
(air mass/flow) and not just engine RPM. The propose of either is to provide the
ECM (engine control module) the key parameter of engine load used to determine
the required fuel quantity injected.

special tool

Loren - this is the 951 board - we are about 25 steps ahead of you ,man. This isn't the carrera 3.2 board.

If you start saying your "chips do nothing" **** in here, they are going to flame you like you won't believe.

jimbo1111

You can't use a maf signal directly. Unless you use a piggy back with a conversion table built in or a maf chip that Vitesse sells. Both ways work well up to 72 lb injectors. After that the injector duty cycle gets to low at Idle. Most of us will never get to the point of using larger injectors than 72lb. Unless of course your over 480 to the wheels.

The easiest and most economical way is to use afm chips with a properly sized maf meter and a piggy back with a conversion to afm signal. This will not throw off the timing as some believe.

Tom M'Guinn

That was my first reaction to this post too, but re-reading the question, it did seem to call for someone to point out the basics of a MAF -- i.e., that its output is not a direct function of rpm (as the question seemed to assume) and is rather a function of all the variables that contribute to overall load (e.g., uphill at WOT in the snow at 4k rpms will produce a much different MAF voltage than feathering the throttle downhill in the summer at 4k rpm).

J Chen

Hi Tom,
Yes I understand clearly what's involved. What I'm curious about
is what Sam said. Is it possible to map an accurate chip by just
having a flow chart when theres so may vatiable invovled ?

J Chen

Jimbo,
The easiest and most economical way is to use afm chips with a properly sized maf meter and a piggy back with a conversion to afm signal. This will not throw off the timing as some believe.

What if you're using larger injectors ? Would that mean a custom chip ?

daniel951

I thought 72lbs injectors maxed out before 480?