Map Sensor location, 406 2.1

Jameswithapug · Post by **Jameswithapug** » 18 Feb 2011, 15:26

Can anyone tell me where the map sensor goes on a 2.1 12v. Mines been dangling under the car since i got it. Didnt know what it was until i looked the part number up. Still got the pipe attached to it to.

Also what effect would having this missing have on my engine as at the moment its totally gutless and would be nice if plugging this back in helped in some way.

Thanks James.

Post by **CitroJim** » 18 Feb 2011, 17:26

If the Xantia 2.1TD is the same James then the small pipe connects into the side of the intercooler on the top LH side via a small spigot.

If it's not connected it is measuring atmospheric pressure only and not reading boost pressure. If it cannot measure boost pressure it cannot properly "overfuel" in case of high boost/heavy power demand and your performance will be reduced as a result. Acceleration may be more sluggish than it should be, not that a 2.1TD is in any way sluggish!!!!

If not connected, you'll have a boosts leak from the intercooler and that may dent performance as well.

Fuel economy may suffer too...

Jameswithapug · Post by **Jameswithapug** » 18 Feb 2011, 17:32

Cool thanks Jim. My 2.1 is deffinatly slugish. On the motorway last weekend 4 up i was having to downshift on long hills! Got down to 3rd at one point. Not ideal. Il go have a look if i can see where it goes and let you know how i get on.

Post by **CitroJim** » 18 Feb 2011, 17:43

Jameswithapug wrote: My 2.1 is deffinatly slugish. On the motorway last weekend 4 up i was having to downshift on long hills!

That's not right James

On a 2.1TD you should be able to engage 5th and then forget all about gears until you need to come to a halt.

Hope it fixes it, if not, you know where we are

Jameswithapug · Post by **Jameswithapug** » 18 Feb 2011, 17:45

Cant see it. Then theres not much room there anyway. I might take out the air filter box tommorow and see if that helps. Looking at where the plug is id say it was more likley on the bottom of the intercooler.

Post by **CitroJim** » 18 Feb 2011, 17:49

Yes, you'll need to take the airbox out and you may even need to tilt the coolant rad forward to expose the side of the intercooler. The spigot is (from memory) pretty well hidden...

Jameswithapug · Post by **Jameswithapug** » 18 Feb 2011, 17:55

Ok sounds like a job for tommorow then as its getting dark now. Thanks again Jim let you know how it goes.

Jameswithapug · Post by **Jameswithapug** » 19 Feb 2011, 17:27

Ok good news is i refitted the Map sensor and it seems better. Unfortunally i cant test it that well as my hydraulic clutch has now gone. Been spongy since i got it and only bitting just off the floor so i thought while the air and battery boxes where out the way id pull it out and see if it was leaking. Big mistake because now theres no pedal atall! Getting really hacked off now. Didnt pay much for it in the first place so its touch and go now weather i cut my losses and weigh it in and go back to German cars.

Post by **CitroJim** » 19 Feb 2011, 17:33

James, before you go and do anything rash like scrapping it, have a look at this (admittedly long) thread..

Sorting a hydraulic clutch

In those 11 pages you'll find out all you need to know about the slave cylinder and how to bleed it.. If need be, I can supply additional information on how to reassemble and exploded slave cylinder...

Good news on the map sensor by the way...

It's not all over yet for the 406...

Jameswithapug · Post by **Jameswithapug** » 19 Feb 2011, 18:36

Ok thanks again Jim, iv calmed down a bit now. Im an engineer so can make up the bleed nipple assembly you come up with. Will give it a try next week. Nothing to loose i guess.