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Tank

Member Since: 25 Jul 2014
Location: Fife
Posts: 431

MAF Sensor

OK so I changed my MAF sensor as it was reading 4.4 on my friends Nanocom.

It has made a real difference and the car picks up and runs better.

One question though, how does the MAF work ?

Looking at it, its a plastic tube with some sort of sensor in the air flow part and some mesh gauze at either end of the plastic tube ? Would be interested to know how it works ?

Also

How and why do they break / go wrong. If its only handling air why would it break ? Mine was a bit oily ? Is that a problem.

Damn thats two questions, gona get ribbed for that !

Be gentle with your answers as I know you are all nasty people on this forum

17th Nov 2015 6:16pm

dorsetsmith

Member Since: 30 Oct 2011
Location: South West
Posts: 4554

The MAF sensor works on the hot film principal. The MAF sensor has 2 sensing elements contained within a film.
One element is controlled at ambient temperature e.g. 25 ° C (77 ° F) while the other is heated to 200 ° C (360 ° F) above this temperature e.g. 225 ° C (437 ° F). As air passes through the MAF sensor the hot film will be cooled. The current required to keep the constant 200 ° C (360 ° F) difference provides a precise although non-linear signal of the air drawn into the engine. The MAF sensor sends a voltage of between 0 and 5 volts to the ECM,
proportional to the mass of the incoming air. This calculation allows the ECM to set the EGR ratio for varying
operating conditions. Inputs / Outputs
The MAF sensor receives battery voltage (C0149-3) via the ECM on a brown/orange wire. Signal output on a
slate/light green wire from the MAF sensor (C0149-2) to the ECM (C0158-11) is a variable voltage proportional to
the air drawn into the engine. The MAF sensor is provided an earth (C0149-1) via the ECM (C0158-20) on a
pink/black wire. The MAF sensor can fail or supply an incorrect signal if one or more of the following occurs: • Sensor open circuit. • Short circuit to vehicle supply. • Short circuit to vehicle earth. • Contaminated sensor element. • Damaged sensor element. • Damaged wiring harness. • MAF sensor supplies incorrect signal (due to air leak or air inlet restriction). In the event of a MAF sensor signal failure any of the following symptoms my be observed: • During driving, engine speed may dip before recovering. • Difficult starting. • Engine stalls after starting. • Delayed throttle response. • EGR inoperative. • Reduced engine performance. • MAF signal out of parameters. In the event of a MAF sensor failure, the ECM will use a fixed default value from its memory.

i found this

17th Nov 2015 6:52pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20172

From a laymans and point of view most of them go downhill due to being contaminated over time.
The filter does a good job but over a long period they do get a bit dirty.

I personally don't believe such things can be cleaned sucessfully myself without further problems due.
Best to replace in my opinion.

Mine is a 2.4 not a TD5 and has been in since new and hasn't caused a problem at all.
It could likely do with being changed over though..

17th Nov 2015 8:45pm

Tank

Member Since: 25 Jul 2014
Location: Fife
Posts: 431

Thanks Dorsetsmith

I had done a Google search before I asked and I suppose what I was after was a non techy response but yours was interesting so thanks

Tank

17th Nov 2015 9:41pm

Tank

Member Since: 25 Jul 2014
Location: Fife
Posts: 431

Thanks Custom90Steve

Defender has 167,000 in the clock so could be original MAF

17th Nov 2015 9:42pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20172

If that the case then it most certainly would be a good idea to change.

17th Nov 2015 9:48pm

Loz2286

Member Since: 31 Aug 2015
Location: High Wycombe
Posts: 121

OK...I'm really a Series guy so anything involved ECMs is alien to me. My 110 is 15 years old with 134k on the clock. Seems fine to me, but I have no comparison in performance. How would I know if my MAF is FUBAR? 1999 Td5 110 CSW
1961 Series 2 88 LPG

18th Nov 2015 5:27pm

mk1collector

Member Since: 17 Sep 2009
Location: West Yorkshire
Posts: 6769

If you unplug the maf and take it for a run there should be an improvement in response which indicates the maf is dud or if you look on the bas tuning (site sponsor) website there is a guide to check with a multimeter. Bas also sell new mafs

Ray
My build thread
http://www.defender2.net/forum/topic17615.html

18th Nov 2015 6:54pm

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