JCNNJC

Last night while trouble shooting an intermittent no start problem,(I was using the DME checks from the factory manual) I found the voltage going into the Mass airflow sensor was low 5.05 volts (manual said min of 8 volts)
Then when I open the flapper door there is no increase in voltage, stays right at 5.05, (No diff if I start the car or not)

Do I have a DME problem or a MAS problem, when I pulled the plug to the MAS and checked the voltage with it disconnected, it is less then 5 volts,
But I guess it uses the DME uses the MAS as a reference to supply voltage?

Do I need a MAS or a DME?
Thanks,
Jim

MHT

what type of car? All the newer 944 operate with a 5v ref. voltage. This is supplied by the ECU and modified by the sensor and returned as a lower voltage signal to the control unit. Do you have an aftermarket air flow sensor? If not, then it is not a mass flow sensor.

JCNNJC

The 944 is a 87, the manual did not say there was a difference in the years,
So may be its, ok, but the voltage did not change when I moved the flapper.
Thanks
Jim

SoCal Driver

You might have been measuring at the wrong pins on the connector.

It's not unusual to open the cover on the AFS (Air Flow Sensor) and see the wipers setting on a worn part of the carbon coated ceramic base resistor. You can repossition these. Check out www.frwilk.com

If you have a "door" and no heated element you do not have a MAS.

porshhhh951

the MAF mass air flow sensor uses a "hot wire" system that gets rid of the old "barn door" so if you still have the flap you dont have a maf system

JCNNJC

Yes I have the AFS style, not a MAS, I took the black plastic cap off and cleaned the wiper and adjusted where the wiper rides, per the website http://www.frwilk.com/ All is well now!
Thanks for all the input!
Jim

SoCal Driver

Fantastic! Drop Wilks a message that you used his info.