57 replies to this topic

[pete l]

OK, so I have different coloured wires, I have Yellow, red and purple.

 

 map1.jpg   33.93K   1 downloads

 

 map2.jpg   33.59K   0 downloads

 

Another thing that I have never seen that shows up in the photos is someone has scribed letters on the plug. Someone has been in there, why else would there be writing on the plug.  

 

I have measured this, the purple one is ground, the yellow is 5 volts which means the red one is signal back to the ECU.

 

 

[Wiggy]

I think that:

 

Purple should be 5V

Red should be Signal

Yellow should be Ground.

 

So it looks like someone has got mixed up!

[pete l]

MY WIRING IS WRONG.

 

I've just tested a MAP sensor with the power on "the wrong way" and it works. It works, IT F****** WORKS. I am over the moon.

 

Thank you everyone on here, thank god for this forum. I love you all. 

 

xxxxxxxxxxxxx

[rich_959]

Wooo, that was tense. I've been watching this thread thinking "why on earth did I buy an MPI?!"

 

Glad it's sorted. You've got plenty of spare sensors now!!

[Sprocket]

Well, in that situation there was never a good chance of a one getting to the real problem applying advice based on an un altered system. What you have there is an altered system which is wrong. I had suspicions early on and why I hinted at you to look at actual wire to terminal configurations.

Glad you got there in the end

Edited by Sprocket, 12 June 2018 - 12:58 PM.

[pete l]

I now need to rip appart the wiring loom to see what's been done to it.

 

Is this a common faillure this part of the loom ? I know about the coolant temp sensor, and I've heard about the TPS wiring chafting, but never heard of the MAP causing problems.

[cian]

What year is your mpi Pete? I had one in over the weekend and it had a black map plug

[pete l]

It was first registered in July 1997. It did come with a brown map. I don't know the difference between the two.

[cian]

I wonder was there a wiring change through the mpi production? I believe the one I had in was an early mpi it had a black map plug, my car is a 99 with a white plug

[pete l]

There was an ecu change. So maybe there was a wiring change

[pete l]

Here's what I have just found. Is this a Rover bodge or has someone managed to find a new plug and solder it in ?

 

 IMG_20180508_150858.jpg   69.58K   0 downloads

[cian]

Looks like someone has been there before doesn’t appear factory! So the loom wasn’t good after all

[pete l]

The loom itself was fine, in that there were no shorts, good connections to the ECU etc. 

 

The problem was that I didn't know which pin the 5 volts should have been going to. I never ever ever thought of crossed wires on what looked like an original engine harness.

 

I found that the 5 volts was on the puple wire and used that reference to test my MAP sensors, I was convinced they were all dud, even the one you sent me. I never thought I was doing anything wrong because I was getting a voltage reading out of the signal wire.

 

Usually, an electronic device either doesn't work or blows up if you power it up the wrong way round. 

 

These MAP sensors are strange

 

Pete.