Can anybody identify this MAP sensor?

[stevieturbo]

At this stage, you really want to manually confirm if the sensor is calibrated correctly now.

Sealey VS403 or Mityvac MV8500 or similar will allow you to do that

Yes it's more money, but if you can at least prove the current calibration is correct, it will mean when you wire it correctly you will not need to remap anything.

ebay usually best bet for cheap versions of the above, but make sure you get one that offers both vacuum and pressure readings. As a lot only do vacuum.

[MC_Bob]

I have a lot of pressure gauges and compressor with regulator. I should be able to use that. Just need a 5v stable power supply. Or I guess I could leave it connected to the car and plot them at different pressures there.

Cheers mate.

[stevieturbo]

I have a lot of pressure gauges and compressor with regulator. I should be able to use that. Just need a 5v stable power supply. Or I guess I could leave it connected to the car and plot them at different pressures there.

Cheers mate.

Read the output voltages on SCal or Smon with it wired as it is now.

Then connect it correctly and do the same, the ecu is the 5v supply ( when wired correctly )

[MC_Bob]

Yep that sounds the best thing. Cheers buddy.

[stevieturbo]

Whoever tuned it originally should have picked up that the MAP sensor was giving odd readings....

However at the same time, given it is an unknown sensor, it could have been something silly like say a 0-100psi sensor so it's output voltage in the range you would realistically be using as a MAP sensor, could be in 0-3v region anyway so the supply problem may not have been so obvious.

Some people do fit strange sensors so their output just is what it is. Doesnt necessarily make it wrong, just a bad choice.

Clearly in this case the wiring was wrong, but the sensor was obviously working as you've been driving the car ? So to any tuner, it may have just appeared as a bad choice, than a fault.

[MC_Bob]

Ive attached a file of the map linearisation.

He supplied the sensor, and as far as Im aware, they all come with a certificate with the information and details of the sensor. These must have been wrong if the sensor is sold to run on 5volts and are a scaled down version.

Ill know just how far out. Ill apply a range of pressures with a gauge and see what SCAL says the readings the syvecs have. Will be interesting..

[stevieturbo]

Only way to be sure is always test. And always test.

presumably key on engine off the sensor was reading approx atmospheric ? ie 1000mbar ?

What was it around idle ? or on the overrun ?

[MC_Bob]

Hi mate.
Managed to just plot the readings as it stands.

With no pressure to sensor, MAP1 was 0.984, and voltage was 0.938
1bar to sensor. 2.01 MAP1, 1.7V
2bar to sensor, 3.2 MAP1, 2.38 V
3bar to sensor, 3.5MAP1, 2.5V
4bar to sensor, 3.5MAP1, 2.5V

So will rewire to 5v and plot.

Critically, it looks as if the 0-2bar range is accurately reported. So will see what the 5v and try to replicate the plot.

How annoying..

And 5v readings are :

No pressure to sensor: 1.613v
1bar to sensor : 2.776v
2bar to sensor: 3.866v
3bar to sensor: 4.824v

So looks like its a 0-4bar sensor. Will plot and see what happens!

[stevieturbo]

Does your first test correspond with the sensor linearisation in use ?

If so, then all should be well when you re-calibrate and run it off 5v.

[MC_Bob]

]Im still learning, so not sure what you mean. But here are screen shots of before and after. The cars quite loud so can only idle. But its running and idling with it off the 5v rail.
Tommorow Ill take it for a drive.

Idle was sitting at 0.4bar with the new sensor. Engine off was 1bar on the dot.