Dear All,

Question - on the 4.4 M62 engine is there an Manifold Absolute Pressure sensor and if there is, where is it? I've looked on RAVE and can see the diagrams but then RAVE talks about "the crankcase ventilation system is pressure regulated by a valve mounted at the rear of the inlet manifold." Is this a mechanical device or, like the thermostat, electronic?

Clearly there's the Mass Air Flow sensor but its not that I mean.

Any advice would be welcome?

Kind Regards

John

...."valve mounted at the rear of the inlet manifold."

This is a mechanical device (simple diaphram with coil spring to provide pressure) Howard
____________________________________________________
2002 4.4 V8 LPG Tartarini
Have RSW AllComms in Cheshire J17 M6 - happy to help.
*Gone: Classic Vogue SE Auto V8 3.9

It's a combined sensor mass air flow (MAFS) and intake air temperature (IAT) it's the same as a MAP sensor...

Under engine management system - sensors.





Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated  Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

To explain a bit more, early fuel injected engines had a MAP, they soon changed to a MAF as they are far better and measure more so you haven't got one on an M62 but you have got a MAF.... if that makes sense....!!! Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Hang on though, a MAF meter and a MAP sensor don't do exactly the same thing. The MAF measures the volume of air entering the engine, the MAP (where applicable) gives the intake air pressure - on cars with forced induction. The 4.4 V8 is naturally aspirated, so there's no real need for a MAP sensor.  Visiting from DISCO3.CO.UK
Discovery 3 TDV6 Auto HSE Zambezi Silver

Oh, OK then, I'll shut up..... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Please don't take it personally though.  Visiting from DISCO3.CO.UK
Discovery 3 TDV6 Auto HSE Zambezi Silver

I was answering the question in a way most folk would understand it, I said "it's the same as a MAP sensor..." what I should have said is they both do basically the same thing, they tell the engine ECU how much air is going into the engine...

A MAP measures pressure, they are used on normally aspirated and forced induction, and measure positive and negative pressure, ie, vacuum

A MAF measures mass air flow, ie how much air the engine is using...

The main reason they moved from MAP to MAF (and most forced induction engines use a MAF these days) is because it is VERY accurate even at low air flow levels. Because of this MAF sensors give better MPG’s and emissions.

There is always the exception to the rule and the Evo X uses both!!! Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Yeah, I know what you're saying and wasn't meaning to contradict that side of it.

It's just a different perspective for those of us from the turbo diesel LR world where they all have both.

 Visiting from DISCO3.CO.UK
Discovery 3 TDV6 Auto HSE Zambezi Silver

Reminds me of the posts you see on classic car forums regarding Ameters vs. Volt meters.
They both effectively tell you the same thing - the general health of the electrical system/battery - but measure it in a different way.

Along a similar theme MAF vs. MAP - give same basic end result 'air measurement' they just come to it in a different way. There's more than one way to skin a cat.

Another advantage of a MAF sensor is they're normally easier to clean. Once a MAP sensor gets muck in it, it's pretty much a case of replacement, if they end up with petrol vapour in them then they're often toast too. SPI Rover's with the sensor in the MEMS ECU were a bit problematic as i recall, if the engine back fired it could send a whole load of unburned fuel into the ECU housing via the vac hose.

Hi Guys

Brilliant Thanks for the all of your replies. One thing I didn't realise was that the battery had to be disconnected and the new sensor 'reset'!

Thanks again

Regards


John

Zirconblue wrote:

Reminds me of the posts you see on classic car forums regarding Ameters vs. Volt meters.
They both effectively tell you the same thing - the general health of the electrical system/battery - but measure it in a different way.

Along a similar theme MAF vs. MAP - give same basic end result 'air measurement' they just come to it in a different way. There's more than one way to skin a cat.

Quite a good analogy actually, because while each can be used as a measurement of the same, they are also tasked to to different things. A MAF can skin a cat better than a MAP, but a MAP is also used for skinning dogs!

Quote:

Another advantage of a MAF sensor is they're normally easier to clean. Once a MAP sensor gets muck in it, it's pretty much a case of replacement, if they end up with petrol vapour in them then they're often toast too. SPI Rover's with the sensor in the MEMS ECU were a bit problematic as i recall, if the engine back fired it could send a whole load of unburned fuel into the ECU housing via the vac hose.

It varies though. I've cleaned (ish) my MAP a few times, but would touch the MAF unless it was already faulty, because it's extremely fragile.  Visiting from DISCO3.CO.UK
Discovery 3 TDV6 Auto HSE Zambezi Silver

Clean a MAF by jet washing it with carb cleaner, you have to do it more often if you off road...

Never reset one when fitting a new one... maybe I've been lucky...  Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Exactly that, they just wash out with carb cleaner, but i certainly wouldn't consider mechanically cleaning it, as they are indeed fragile, but carb cleaner usually brings them up like new.

Even that would be considered a risk for mine though.  Visiting from DISCO3.CO.UK
Discovery 3 TDV6 Auto HSE Zambezi Silver