Author Topic: MAT sensor -40 deg c  (Read 5189 times)

Offline Dylan@AM Racing

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MAT sensor -40 deg c
« on: May 07, 2010, 03:40:46 am »
This is a new install and I'm new to vems. This is an Audi S4 AAN. Any help would be much appreciated. One of my problems is this: The manifold air temp display on megatune shows -40 deg c. Sensor tests fine as does voltage to the pins. With the ignition on the gauge does not change colour i.e. from pink to white with ign on. Same colour issues with engine speed and pulse width.
Thx in advance....

Offline gunni

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Re: MAT sensor -40 deg c
« Reply #1 on: May 07, 2010, 04:59:21 am »
This suggests that the sensor is not connected to the Vems unit.

Offline Ascona 400

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Re: MAT sensor -40 deg c
« Reply #2 on: May 07, 2010, 07:49:33 am »
I've also hade this happening one time.
The cause of it was that when I uploaded the firmware the firmware got patched with some strange values for the MAT sensor. Instead of getting values for a NTC I got values for a PTC sensor.
So test to upload the firmware again and check so that you get the right values loaded for your MAT sensor.

Offline mattias

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Re: MAT sensor -40 deg c
« Reply #3 on: May 07, 2010, 04:26:05 pm »
If you have a PnP unit you need to specify if you're going to use something other than the stock PTC, it clearly says so when you order - or the person you bought it through should've asked or pointed it out since the stock PTC sucks but works adequately with the stock ECU and hot wire air mass measurement.

I always get a new NTC sensor (the open body from the web shop) and install it on a flange screwed into the stock position, or if there is a pressure pipe before the throttle body. On the stock motor there is only  rubber before the throttle so the intake and stock location is the only real option.