Do we have one and is it worth cleaning

Don't even know if we have one, but this thread on Disco3 got me thinking

http://www.disco3.co.uk/forum/topic64159.html?highlight= Former Mod/Member, with the most post & Chicken George Arch nemesis

stupid question: what's a MAP sensor?  2002 Honda VFR800
2002 Toyota Celica 140 Silver (mid life crisis - again!)
2007 FL2 GS Manual Army Reconnaissance Green + freel2.com sticker
2004 Toyota Celica 140 Black - Gone
2000 Toyota Celica 140 Silver - Gone
1998 Toyota Celica ST Pearl Green - Gone
1996 Nissan Primera 1.6 - Gone
1994 Rover Montego 1.6 Auto - Gone

Not sure something to do with manifold pressure, engine load and stuff

I think  Former Mod/Member, with the most post & Chicken George Arch nemesis

They measure the temp and therefore the density of air entering the engine, this is especially important in diesel engine so the engine knows how much oxygen it is swallowing in order to add fuel at the correct rate, before Maps or Mafs engines could feel sluggish on hot days when air is thin or at altitude, years ago my diesel astra was weak on hot days and positivity anaemic during a cross alp trip I once took it on

not sure how a map works but a Maf works by measuring the current needed to keep a piece of wire warm inside the air intake pipe. VW diesels in particular had a bad reputation for Mafs , cleaning or changing them could give the car a new lease of life.(£150 each)

That is a very rough guide to all things engine related as its all hearsay as I know nothing really. just that my astra went like a banshee on cold wet days and not so on hot dry days, whereas as the golf was fairly consistently fast rain or shine. At work
At home

"I can't always believe facts I read on the web" - Charles Dickens

winner by default of the tractor vs caravan race

That's funny I was just thinking the same the other day npinks! I will have a look round tomorrow. I wouldnt be surprised if there was one fitted!

http://www.aa1car.com/library/map_sensors.htm

Might help us know what it is  Former Mod/Member, with the most post & Chicken George Arch nemesis

I know what a MAF (Mass Air Flow) sensor is had an issue with it on my old celica.

We do have one on the FL2 - i fyou open the bonnet it is visible front right on top of the black air ducting. It has a set of wires from it to the engine management magic box.

It is normally held in with a couple of screws. And it basically just hangs in the tube to do its job.

I'm sure someone told me once that it is a little turbine type thing which spins as the air passes it??? but don't hold me to that.

Anyway very easy to check it I would guess. 2002 Honda VFR800
2002 Toyota Celica 140 Silver (mid life crisis - again!)
2007 FL2 GS Manual Army Reconnaissance Green + freel2.com sticker
2004 Toyota Celica 140 Black - Gone
2000 Toyota Celica 140 Silver - Gone
1998 Toyota Celica ST Pearl Green - Gone
1996 Nissan Primera 1.6 - Gone
1994 Rover Montego 1.6 Auto - Gone

MAP and MAF are different - MAF measures air flow (which tells the ECU the mass of air going into the engine), MAP measures air pressure and can be used for the same purpose, or as a "check", particularly on modern diesels with EGR.

We have both MAP and MAF in our FL2.

The MAP (Manifold Absolute Pressure) is just on top of the electric throttle, in front of the engine.
Also named Boost Pressure Sensor, it measures the pressure inside the intake air duct, after turbo, in order for the ECM to know how much to open/close the variable vanes of the turbo to obtain the desired-for-the-situation boost pressure.

The MAF, in fact TMAF (Temperature and Mass Air Flow) is just after the air filter, on top of the air duct.
It measures the volume and temperature of the intake air. Those two (volume and temperature) are direct dependant one on other. The less temperature, the greater volume/dense the air is for the same airflow/airspeed and viceversa.

Last edited by alex_pescaru on 4th May 2011 10:24 am. Edited 3 times in total

Thanks alex_pescaru

As usual great answers.

Any advice on how to check and clean them? 2002 Honda VFR800
2002 Toyota Celica 140 Silver (mid life crisis - again!)
2007 FL2 GS Manual Army Reconnaissance Green + freel2.com sticker
2004 Toyota Celica 140 Black - Gone
2000 Toyota Celica 140 Silver - Gone
1998 Toyota Celica ST Pearl Green - Gone
1996 Nissan Primera 1.6 - Gone
1994 Rover Montego 1.6 Auto - Gone

I cleaned mine on my last car (Jag X-type), following advice on their forum. On the Jag there are 2 fine wires that measure the passing air temperature and electrical resistance. The wires are in the airflow and can get a dirt build-up on them, this then causes the sensor to tell the ECU to alter the fuelling as the dirt acts like an insulating layer.
The way to clean the wires is to use a solvent spray cleaner (I used a brake cleaner, £1 from £ shop). Remove the MAF sensor from air intake, hold it so spray fluid runs down, and spray liberally onto the wires inside. A word of caution; the wires are very fine and quite delicate. Break a wire and the sensor is scrap. With extreme caution I used a cotton bud to gently wipe the wires whilst spraying. Make sure if you try this to fluff the end of the cotton bud to soften it first.
I noticed a slight improvement in the cars running afterwards, but it did have around 50k miles on the clock when I cleaned it.
Hope this helps.

Russ. Poke it, Poke it, make it do it again!!

Gone - 2008 Freel2 HSE Santorini Black
Hello - 2010 RRS TDV6 3.0 HSE Santorini Black

so we now know what we are looking for (a picture with a red arrow would help me though )

so who with a technical knowledge [cough cough Alex] is going to have a look and see if we should be cleaning them like the disco3 boyz to get the improved results as they report  Former Mod/Member, with the most post & Chicken George Arch nemesis

npinks wrote:

a picture with a red arrow would help me though

I'm so very sorry - I just couldn't resist.

The things you do to brighten the day.

Click image to enlarge

 2002 Honda VFR800
2002 Toyota Celica 140 Silver (mid life crisis - again!)
2007 FL2 GS Manual Army Reconnaissance Green + freel2.com sticker
2004 Toyota Celica 140 Black - Gone
2000 Toyota Celica 140 Silver - Gone
1998 Toyota Celica ST Pearl Green - Gone
1996 Nissan Primera 1.6 - Gone
1994 Rover Montego 1.6 Auto - Gone

 Former Mod/Member, with the most post & Chicken George Arch nemesis

THERE ARE TWO ARROWS IN THAT PIC, WHICH IS POINTING TO THE MAP? AND WHICH TO THE MAF? AND WHY AM I shouting  At work
At home

"I can't always believe facts I read on the web" - Charles Dickens

winner by default of the tractor vs caravan race