MAF & throttle body

[alanmarsh200]

hi all, 1999 carrera 3.4 with ordinary cable throttle.
when installing 48mm individual throttle bodies,how do you overcome the input to the ecu from the MAF sensor which no longer has any housing etc etc.
thanks in advance

[Ian_UK1]

alanmarsh200 said:

hi all, 1999 carrera 3.4 with ordinary cable throttle.
when installing 48mm individual throttle bodies,how do you overcome the input to the ecu from the MAF sensor which no longer has any housing etc etc.
thanks in advance

You will have to have your ECU converted to use Alpha-N mapping. The facility already exists in the Bosch ECUs (it's how they still manage to run when the MAF is disconnected) but the mapping would need to be very carefully tailored to your setup and other changes made to ensure no error codes were thrown.

Alpha-N mapping uses a table with values for air mass at various throttle openings instead of directly measuring the air mass entering the engine with an Air Mass Meter. This table effectively provides the 'load' portion of the load/rpm matrix in lieu of the MAF sensor readings. Using Alpha-N enables the Air Mass Meter to be removed from the inlet tract improving airflow into the engine and allowing, in theory, for greater power outputs as a result. Obviously the accuracy of the values in the load table are critical - if they're (even a little) wrong, your A/F ratios will be a mile out with all the potential issues that can bring.

My suggestion would be to speak to Wayne Schofield at Chip Wizards. He maps hundreds of Porsche racers and I know he's done some work recently (for my local porsche independent) on a 996-based car fitted with individual throttle bodies.

Edited by Ian_UK1 on Sunday 8th May 11:37

[alanmarsh200]

thanks Ian, just the info i was looking for.
Regards Alan

[danielw]

What's the benefit in terms of changing the throttle bodies? What else are you doing?

[alanmarsh200]

high flow equal legnth ex manifols, 100 cell sports cats & silencers. cams. rods, combustion chambers, total remap. etc etc

[danielw]

Sounds like an expensive proposition! Was this after an engine failure or a rebuild for fun? What are you aiming / expecting in terms of output?

[dom9]

Did anything ever come of this project?

Can the standard, cable, Bosch ECU be run in alpha-n mode, so a TB conversion would just require the mechanical equipment?

[Slippydiff]

dom9 said:

Did anything ever come of this project?

Can the standard, cable, Bosch ECU be run in alpha-n mode, so a TB conversion would just require the mechanical equipment?

As I understand it the Manthey K400 conversion to the Mk 1 996 GT3 does away with the MAF sensor and runs Alpha-N whilst still utilising the Bosch ECU. (Though it doesn't run individual throttle bodies)

Edited by Slippydiff on Thursday 3rd November 22:37

[Pat_T]

old thread resurrection time!

does anyone have any more info on this?

Specifically any confirmed individuals/companies that can map the Bosch ECU to run AlphaN in this manner?

I am considering doing something similar...

[Ian_UK1]

Pat_T said:

old thread resurrection time!

does anyone have any more info on this?

Specifically any confirmed individuals/companies that can map the Bosch ECU to run AlphaN in this manner?

I am considering doing something similar...

Wayne Schofield at Chip Wizards can definitely do this for you