Where would I find?

tim leech · Post by **tim leech** » 08 Sep 2009, 09:23

The manifold pressure sensor on my MK1 Xantia 1.8i 8v please, im eager to locate it and give it a clean out as im told by Sir Jim that this may be a reason why it doesnt run right.

Im not that mechanically minded so a diagram or laymans terms please!

MikeT · Post by **MikeT** » 08 Sep 2009, 13:39

The MAF? It'll be somewhere between the air filter and engine. Either in the pipework or the manifold. Look for an inline device in the induction system that has two or more wires plugged into it.

Please be aware the small sensing wire is very delicate and easily broken but will probably have a coating of cooked on crud. Worth spraying with carb cleaner but if you have to rub it, be gentle and use something no-abrasive like cotton wool etc.

tim leech · Post by **tim leech** » 08 Sep 2009, 16:56

Thanks Mike, would this cause the emissions to be out, mine failed the MOT by a MILE today!

Post by **myglaren** » 08 Sep 2009, 17:33

I think there may be a bit of confusion here MAF and MAP are not the same.

I haven't a clue where the MAP is but either Cloggz, Addy or VertVega have a description that I'll try and locate.

The MAF is as Mike described but it only senses the airflow (Mass Air Flow (meter)) and in mine also the temperature of the incoming air.

This is mine:

yours will be similar. (click for larger image).

The MAP, as you'd expect, measures the pressure in the inlet manifold.

citronut · Post by **citronut** » 08 Sep 2009, 19:37

on VAU***lls i belive its on the end of the induction manifold

regards malcolm

vince · Post by **vince** » 08 Sep 2009, 20:11

Tim, if you give us a call at the shop tomorrow we now have the Citroen program so we can locate it for you

0151 525 1764

tim leech · Post by **tim leech** » 08 Sep 2009, 20:14

Cheers guys, mines a 1.8 PETROL with magnetti marelli electrical bits, THE CO was over 5.5!

MikeT · Post by **MikeT** » 08 Sep 2009, 21:03

If it's a MAF it may be remotely located with just a small vacuum pipe feeding it (as it as on my Vauxhall Malcolm

) but the vacuum pipe will still be found between the air filter and engine.

DickieG · Post by **DickieG** » 08 Sep 2009, 21:28

I think you'll find the sensor located on the offside of the bulkhead with a vacuum hose running to the manifold. Remove the hose from the sensor then blow through the hose to see/dislodge any sludge build up in the manifold take off point.

tim leech · Post by **tim leech** » 09 Sep 2009, 09:47

Thanks guys I will let you know how I get on!

tim leech · Post by **tim leech** » 12 Sep 2009, 20:14

Well if found it, its a small flat plastic box with an electrical connector and a pipe coming out of it?, gave it a good blow but didnt seem to do any difference! I cant suck anything out or blow through it if you know what I mean. When i took the pipe off the car rang like a bag of nails, is it worth cleaning it out with anything?

DickieG · Post by **DickieG** » 13 Sep 2009, 09:43

You won't be able to suck or blow anything out of the sensor, what you need to check is whether there is any obstruction at the manifold end of the vacuum pipe. Remove the pipe from the sensor then blow down it. i.e. towards the manifold as there is a tendency to get a build up of sludge where the pipe is tapped off of the manifold.

tim leech · Post by **tim leech** » 13 Sep 2009, 19:22

Had the pipe off today and its clear, so maybe the sensor itself thats duff, will go find a replacement then

tim leech · Post by **tim leech** » 16 Sep 2009, 20:03

New sensor fitted today, I havent plugged it into the emission tester but it sounds the same, and still smells rich and doesnt drive any different.

Im starting to loose patience now, anyone got a match and a can of petrol

MikeT · Post by **MikeT** » 16 Sep 2009, 20:27

The MAF is part of a complex system so it could have been contributing, despite a new unit not curing the overall problem. Additionally, you might have to give the ECU time to re-learn and re-calculate it's maps which can only happen once it's up to temperature and running in closed-loop mode.

Have you had the codes read and if so, what was the result? It's relatively easy to test these sensors if you're inclined and have the time. I'd start with the engine coolant (prime suspect) then the HEGO (though it shouldn't create excessively rich conditions) if it's running rich. Whatever you do, try not use it unless cured as the excess fuel can destroy/poison certain components eventually.