# Z32 maf on charged side of intake?



## Stephen Max (Aug 18, 2003)

Howdy folks,

Has anybody here run a Z32 maf on the charged side of the intake? How much boost can they handle before they go bad?

Thanks!

Steve


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## chimmike (Oct 17, 2002)

why even test that? Put it before the turbo.


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## TheVodKA (Sep 19, 2002)

Chimmy, I think this is referred to as a blow-through setup. There is a person on NICO who did this on a 240 IIRC, but I don't remember the results. Search there to find out.


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## Stephen Max (Aug 18, 2003)

chimmike said:


> why even test that? Put it before the turbo.


The reason I ask is because I have been having driveability problems with the maf placed before the blower.

My particular application is a 95 Maxima with a Stillen supercharger kit, which normally has the maf after the blower. The A32 maf is capable of handling boost pressure, I think some of the turbo guys have run as much as 18 psi with no problems. I recently went to a smaller pulley that is giving me about 11 psi, and as part of the upgrade I sent my ecu to JWT to have it programmed for Z32 injectors (370 cc/min) and a Z32 maf. JWT told me not to have the maf after the blower, so I put it about a foot upstream from the blower inlet. I also ran a recirculation hose from the bov to the pipe between the maf and blower.

This situation works well as long as I'm at more than half throttle, but at very light throttle positions (such as when cruising) the engine is very erratic feeling. It is very sensitive to throttle position right at tip in.

I think this is because I get sufficient backflow from the blower and/or recirc hose to cause it to run rich when backing off the throttle, then when I give it a little gas it bogs for a second. It is very annoying. I think the problem is more severe with the supercharger (compared to a turbo) since it pumps a substantial amount of air even at low engine load, being rpm dependent and not exhaust gas velocity dependent. 

Putting the maf back to the original position between the blower and the throttle eliminated all the problems, but I'm wondering how long the maf will last.


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## 180SX-X (Sep 21, 2003)

try recurculating b4 the MAF, this might solve it...or not sine u say ur running rich...


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## Stephen Max (Aug 18, 2003)

180SX-X said:


> try recurculating b4 the MAF, this might solve it...or not sine u say ur running rich...


That would be equivalent to discharging to atmosphere. I tried that and it works as long as I tighten the bov fully so that it does not release air at idle. But I still get backflow from the blower when shifting or letting off the throttle, and the maf is metering the backflow, causing the engine to run momentarily rich. I looked at my plugs the other day and they were completely covered with soot. So I've gone back to having the maf on the pressurized side. We'll see how long it lasts.


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## Crazy-Mart (Jul 14, 2002)

i run a maf after my turbo on my E15t ... using the original TBI i had to do this ... i think that as long as the temperature of the air is cool enough it should last very long ... and air temperature probe should be moved to... at least to get the correct correction factor for the ECU calculation .... as the wire calculate air flow with the temperature change (resistor type) as much more air cools the wire (maf)... air temp is very important to get the Ecu to know exactly the right correction factor ... so move it with the maf...

my 2 cents


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## Stephen Max (Aug 18, 2003)

Crazy-Mart said:


> ... and air temperature probe should be moved to... at least to get the correct correction factor for the ECU calculation .... as the wire calculate air flow with the temperature change (resistor type) as much more air cools the wire (maf)... air temp is very important to get the Ecu to know exactly the right correction factor ... so move it with the maf...
> 
> my 2 cents


Do you know if the JWT programmed ecu uses intake air temp sensor information?


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## morepower2 (Apr 19, 2002)

180SX-X said:


> try recurculating b4 the MAF, this might solve it...or not sine u say ur running rich...


That would dump metered air and it would run even richer.

Mike


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## morepower2 (Apr 19, 2002)

Stephen Max said:


> The reason I ask is because I have been having driveability problems with the maf placed before the blower.
> 
> My particular application is a 95 Maxima with a Stillen supercharger kit, which normally has the maf after the blower. The A32 maf is capable of handling boost pressure, I think some of the turbo guys have run as much as 18 psi with no problems. I recently went to a smaller pulley that is giving me about 11 psi, and as part of the upgrade I sent my ecu to JWT to have it programmed for Z32 injectors (370 cc/min) and a Z32 maf. JWT told me not to have the maf after the blower, so I put it about a foot upstream from the blower inlet. I also ran a recirculation hose from the bov to the pipe between the maf and blower.
> 
> ...


Swirl and turbulance caused by the compressor can make the MAF reading go nuts. You want to have the MAF at least 18" and a turn away from the compressor. Also you don't want air blowing accross your filter. Ideal is tho have the filter, a length of pipe at least 6" long, then the MAF then 18" of pipe and a bend before the blower with a recirculated BOV as close to the compressor as posible.

The program is not calibrated correctly to measure denser compressed air after the blower. The reason why you don't do this is that the air desnity is not constant after a blower which makes the programing difficult.

Mike


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