Problems with Hitachi MAF in 100 mm housing

[Treurentner]

Anyone using the #12576410 or #15865791 Ls3 LS7 etc... Powrmax 100 mm Maf sensors? Any known problems?
My Maf frequency is in the range of 600 Hz at idle (427cui) what is 300% off from the expected level, so I´m out of range - 411 PCM table starts at 1500 Hz... watch the log
All recommendations welcome
Kind regards
Marco

[Treurentner]

Ok - finally I can give the solution and the answer is:
NO it will not work in boosted applications - IF...

you have (or get) turbulent airflow.

This may caused by an improperly installed or missplaced bypass valve or
insufficient size of bypass valve.

The valve (Procharger race style) was mounted before and after the intercooler to check what´s working....

the theory:

the bypass valve is needed to minimize parasitic loss of the supercharger in NA condition, minimize the load on the SC bearings, improve durability, prevent extrem loads on the impeller on sudden load changes (WOT - IDLE - WOT)...

the reality:

the bypass valve is creating highly turbulent airflow while dumping the air.
the turbulences were transported via the ducting until the throttle blade.
the intercooler helps to laminating the flow again
laminating directly depends on the size and the flow resistance of the intercooler
turbulent flow directly depends on size of the ducting in relation to size of the dump valve
a dump valve after the intercooler produces heavy turbulent airflow, especialy on a dual intercooler setup

the solution:

EASY :-) use SD tune...

if not SD - in case you want a daily driver in all wether an environment conditions
or you need to meassure the load (tranny pressure calculation) instead of estimating
do NOT use a Hitachi MAF hot film sensor style...
use the heatwire (old) style sensors like Granatell, LS6 etc... only.

Use an SSQV bypass valve instead of the dump valve (that is closed at idle and much less turbulent flow exists.

Have a strait duct passage 2 feet before and after the Hitachi MAF
Do not place this sensor just before or after a bow.

Place your dump valve ALLWAYS befor the intercooler and use a single cooler (much bigger piece) system only.

Use a small 2." ducting only and no F-Series Procharger (just kidding :-))

I hope this helps the guys that have
rough untuneable idle
non idle to light throttle transition
heavy starting engine with lean condition on startup
on MAF- cars in the 1k hp range...

Marco

[joecar]

Marco,

Very good and interesting observations and explanations... thanks for updating.


Do you have any MAF logs with bypass valve relocated before intercooler...?

[Bruce Melton]

I am not sure I understand where the MAF is in the intake stream?

If you can put it in the "draw through" path, that is- next after the intake air cleaner that would be your best option. It should be fine there for > 750 hp.

Maybe I don't fully understand the configuration you describe but it sounds like you have the bypass valve dumping before the MAF?

Bruce@Powrmax,com

www.Powrmax.com

Ok - finally I can give the solution and the answer is:
NO it will not work in boosted applications - IF...

you have (or get) turbulent airflow.

This may caused by an improperly installed or missplaced bypass valve or
insufficient size of bypass valve.

The valve (Procharger race style) was mounted before and after the intercooler to check what´s working....

the theory:

the bypass valve is needed to minimize parasitic loss of the supercharger in NA condition, minimize the load on the SC bearings, improve durability, prevent extrem loads on the impeller on sudden load changes (WOT - IDLE - WOT)...

the reality:

the bypass valve is creating highly turbulent airflow while dumping the air.
the turbulences were transported via the ducting until the throttle blade.
the intercooler helps to laminating the flow again
laminating directly depends on the size and the flow resistance of the intercooler
turbulent flow directly depends on size of the ducting in relation to size of the dump valve
a dump valve after the intercooler produces heavy turbulent airflow, especialy on a dual intercooler setup

the solution:

EASY :-) use SD tune...

if not SD - in case you want a daily driver in all wether an environment conditions
or you need to meassure the load (tranny pressure calculation) instead of estimating
do NOT use a Hitachi MAF hot film sensor style...
use the heatwire (old) style sensors like Granatell, LS6 etc... only.

Use an SSQV bypass valve instead of the dump valve (that is closed at idle and much less turbulent flow exists.

Have a strait duct passage 2 feet before and after the Hitachi MAF
Do not place this sensor just before or after a bow.

Place your dump valve ALLWAYS befor the intercooler and use a single cooler (much bigger piece) system only.

Use a small 2." ducting only and no F-Series Procharger (just kidding :-))

I hope this helps the guys that have
rough untuneable idle
non idle to light throttle transition
heavy starting engine with lean condition on startup
on MAF- cars in the 1k hp range...

Marco

[joecar]

Post pics.