Map sensor

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Q

quattrowex

New Member
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8
Location
Ireland
Just wanted to see if anyone has the correct voltage readings from a map sensor on a 96 dse , pre egr engine ,
At idle I get 1.8volts - 2.95 volts at 4000rpm . can anyone tell me if thats correct .
There are 3 wires on sensor . 1 is ground the other a 5volt supply or ref voltage and the third the output.
some other sites say that it should give up to 5 volts out at high rpm ?
 
quattrowex said:
Just wanted to see if anyone has the correct voltage readings from a map sensor on a 96 dse , pre egr engine ,
At idle I get 1.8volts - 2.95 volts at 4000rpm . can anyone tell me if thats correct .
There are 3 wires on sensor . 1 is ground the other a 5volt supply or ref voltage and the third the output.
some other sites say that it should give up to 5 volts out at high rpm ?
Click to expand...

It's manifold pressure not revs. At 4500 rpm throttle off = no boost pressure, 2000rpm foot to the floor = something like max boost pressure.
What the voltages should be I do not know but if it's a solid state device I would not expect to see 5 volts.
 
Thanks for the prompt reply , got a better understanding of that now , in relation to what its measuring .
I dont know what the make up of the sensor is though , I presumed the the 5 volt contstant is a input and a reference voltage .
 
The variable output from the MAP sensor is converted in the ECU to a boost pressure reading for fuelling purposes. If you are sitting there with engine at 4500 RPM to measure the MAP output, it is a very silly thing to do if you have an automatic gearbox. You could do serious damage to it.
 
quattrowex said:
Thanks for the prompt reply , got a better understanding of that now , in relation to what its measuring .
I dont know what the make up of the sensor is though , I presumed the the 5 volt contstant is a input and a reference voltage .
Click to expand...

5 volts and zero volts are the supply, the third wire is the signal:)
 
Hi have id on the cables ok , but im trying to find out what the output voltages are supposed to be for normal conditions , im getting idle at 1.8v. is the correct?
 
Live data on Faultmate/Nanocom would tell you if it is working correctly, the voltage is pressure dependant and may not go through the full range possible for the device.
 
The reason for checking this is re a possible gearbox fault , gearbox supplier suggested that the MAP may be an issue with the late changes on the box ,
When in low range the box changes up quickly but in high it revs to 3800 rpm to get to 2nd and the same for 3rd. the box is not slipping or flaring in the changes.
Fluid and filter changed , old fluid good and no dirt in filter,
Box was perfect until the transfer box was changed a while ago.Im just trying to isolate items before i go down the road of changing the box.
 
quattrowex said:
The reason for checking this is re a possible gearbox fault , gearbox supplier suggested that the MAP may be an issue with the late changes on the box ,
When in low range the box changes up quickly but in high it revs to 3800 rpm to get to 2nd and the same for 3rd. the box is not slipping or flaring in the changes.
Fluid and filter changed , old fluid good and no dirt in filter,
Box was perfect until the transfer box was changed a while ago.Im just trying to isolate items before i go down the road of changing the box.
Click to expand...

The MAP sensor has no direct effect on the box shift pattern, it sounds like it's stuck in sport mode.
 
quattrowex said:
The reason for checking this is re a possible gearbox fault , gearbox supplier suggested that the MAP may be an issue with the late changes on the box ,
When in low range the box changes up quickly but in high it revs to 3800 rpm to get to 2nd and the same for 3rd. the box is not slipping or flaring in the changes.
Fluid and filter changed , old fluid good and no dirt in filter,
Box was perfect until the transfer box was changed a while ago.Im just trying to isolate items before i go down the road of changing the box.
Click to expand...

What happens when you press the sport button and drive in high? Normal? (apart from lights/messages)

Mine changed to normal high although display said sport, i.e. on start up always in sport mode, press sport and changed to normal.
All caused bu duff transfer box ecu that i repaired
See all the other threads on this issue
 
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