MAF types (Draw Through/Blow Through) and config

[noshine4mine]

So I am learning about Draw through versus Blow through MAF sensors. From what I can guess the factory air box will use Draw through? I assume my Turbo setup is setup via Blow through.
What does it take to convert from one to the other? Is it just an ECU change in the tune? Does anyone know where that is in HP Tuner's VCM suite?

I ran into alot of trouble with one of my tunes idling like shit. I didn't know about this at the time or I would have asked. Currently I have a good tune under boost but it still does wierd shit. Sometimes dies when the RPM gets too low as im slowing down and the transmission hasnt down shifted yet. The tune also surges when cold. I also wonder if this can affect the transmission causing it to do odd things. If I drive in anything other than normal mode and low RPM the transmission will shift back and fourth from 4th to 5th and 6th to 7th, causing it to clunk when it takes all the lash out of the drive line. Also I watch my AFR gauge in the car when I drive normally it is all over the place sometimes and even at Idle I see the AFR bouncing around more than I would expect.
One tuner kept bringing up something being wrong with the MAF sensor. But I had an old tune that had no drivability issues.

Sponsored

 

[engineermike]

It’s all in the maf period vs mass airflow translation table. You can calibrate that in hptuners if you compare (LTFT + STFT) vs maf period.

 

[ProChargerTECH]

You can't easily do draw through, unless you vent the BOV back into the intake.

Blow through MAF's are perfectly fine until you peg them.

 

[markmurfie]

Vent the BOV back into the intake is one thing, you would also have to have a break out for the IAT and move that into the manifold to get a "post intercooler" accurate air temperature reading.
Pretty much the things PD blower setups do to keep draw through MAF.
Draw through with bad filter placement is prone to cooling fan wash or grill turbulence.
Blow through is prone to compressor fan turbulence which has to do with BOV size and placement.

In both cases you want all the air going into the cylinders to pass by the MAF sensor in smooth laminar fashion to be metered properly. This is where good idle and drivabiity comes from. If you are planning on doing any tuning of the MAF transfer, this makes it easier to know what you are doing and not have your changes come out of noisey data. Digital frequency based MAF sensors have much better consistency in a larger range in different tube sizes compared to older analog voltage based MAF sensors. Pegging an old voltage MAF ment you need a bigger MAF tube and the idle area was going to be sacrificed some with increased turbulence. With digital MAF its not really like that any more as frequencys can get really high to compensate for a small tube. Its still a benefit to match the tube size to not have to use these exetremely high or extremely low frequencies(from an overly large tube), its just not required.

 

[noshine4mine]

Thanks guys,

Just trying to figure out why one tune surges on cold start up and the other tune doesn't.

I had one tuner tell me something was wrong with the MAF sensor. But I could load a previous tune and it had no surging issues.

 

[Angrey]

Thanks guys,

Just trying to figure out why one tune surges on cold start up and the other tune doesn't.

I had one tuner tell me something was wrong with the MAF sensor. But I could load a previous tune and it had no surging issues.

Which tuner?

 

[wish i was fast]

you can built a histogram and tune your maf with hp.tuners

Sponsored