Can anybody identify this MAP sensor?

[MC_Bob]

I had an ECU slung into my Toyota Aristo about 3 years ago. Brief spec is 2JZGTE, FBW, Manual Box. Its an S6 Syvecs ECU.

Basically. I had a spare input which I wanted to use for my aircon now its fixed. This was identified as Pin 58.

Went to use it, found its already connected when SCAL says it should be vacant. Trace it and find its connected to my map sensor.. BUT SUPPLYING the power.

So I go into syvecs and find yes, its running off 3volts, and has had the map altered to 'map around' it. Instead of figuring out why it peaks at 3 volts.

So before I move it to the correct 5v rail, I need to know what it is so I can tell the ECU what the correct pressure to voltage table is.

In true fashion, when I got handed a half finished car, I never got any paperwork for it, and 3 years down the line im slowly buttoning it up.

So anyone? Thanks!!

[stevieturbo]

Could be anything really, from a generic chinese sensor, to anything else

But where was it getting a 3v supply from ?

TBH, given how important manifold pressure is, especially on a boosted engine, I would only be using a sensor I could trust.

I would be very surprised if any such sensor wasnt fully expecting a 5v reference supply and whoever used 3v did so in error.

[TimH]

Syvecs S6 can't generate a 3V supply so this seems suspicious....

Pin 58 is an AU input, so could float at around mid rail...or 3V if the pullup was turned on perhaps.

Just to be 100% sure, have you counted pins on the right rows? Choosing the wrong row would mean "pin 58" would actually be a 5V output, which is what the power pin of the MAP sensor should be connected to of course. But if its only 3V then somethings not right anyway!

As for what the sensor is, no idea...but they almost always have the same pinout when they have a metripack connector, so you could rig it up on the bench, use a DMM to measure the output volts, and apply pressure with a MityVac to characterise it.

[MC_Bob]

Hi guys.
Yes it's definately pin 58. If I remove the load it rises to 5v. So we decided it drops to 3v because of the pull up resistor.
I'm absolutely livid about it but heyho.

That's not a bad idea, but if I get it a little wrong it might be more problems in the long run, and not knowing the max of the sensor too.

If it's not a common sensor should I just replace and alter the linearisation table to suit?

Thanks guys!!!

[TimH]

Every MAP sensor (of that type) I've come across is 0.5V at 0 bar and 4.5V at full range. If you take measurements at 1 bar and 2 bar, you will very easily work out what the max range is. Or, yes, for the sake of £100 or so, get a new one

[MC_Bob]

Thanks mate. I will try and plot data from it.
I am concerned the readings now are not correct and if I do correct it, the car won't run right.

Ie. The cars been mapped at 1.5 bar, but in reality due to running on 3v and him making up data it's only actually 1.3 bar.

[TimH]

Given that the sensor was not wired right and probably giving inconsistent readings I would get the sensor sorted and then the car checked on a RR ASAP.

[MC_Bob]

Thanks Tim.

So much for the best mapper in the world..!

[stevieturbo]

And again.....you keep saying this was running off 3v ?

That cannot be the case as nowhere does the ecu output 3v for such a purpose.

Pin 58 is the input signal from the MAP sensor to the ecu.

Exactly which pin on that sensor is it wired to ( in fact, all 3 pins )?

Are you 100% sure it is wired incorrectly ( and yes I have read you're saying that just want to confirm )

And testing sensors like that with a Mityvac or other proven pressure/vac source is the correct way to calibrate any/all sensors and as Tim says virtually every sensor of that design would generally operate in the 0.5v to 4.5v range.

And depending if the calibration for that sensor is incorrect, then yes the car will likely need mapped again. But prove it one way or the other.

If someone manually calibrated the sensor off the 3v base and it was stable but sensor readings should be correct...then wiring it correctly and re-calibrating should mean no re-mapping is needed.

But again, test the sensor with a Mityvac now to see if all readings are correct, if so then things will be a lot easier for you.

[MC_Bob]

Pin 6 is map ground
Pin 59 is map signal
Pin 58 has been wired to map power

100%

If you remove the map power. Pin 58 floats at 5v because it's waiting for a signal input. With a load, because of the built in resistor it drops to 3v


Thanks so much for the help.

With the help of romain I have checked the pinout a dozen times and 100% correct.

I only found this because I wanted to use the only spare input according to scale as pin 58 for the air con idle pull up.