Methinks me MAF is buggered!

**Ralph1Malph** · 24th February 2013, 06:55 PM

Was driving home from a thoroughly enjoyable club BBQ on Sat when the Disco started 'surging' like it was 'hunting' travelling on the Pac Hwy around 95-100km/hr. Easing off sorted it.

I immediately suspected air starvation as it had that feel to it.

I had the nanocom so hooked it up whilst better half drived. I am still learning it but the relevent reading concerned me. Airflow was zero, zip, nada, nuttin!

Look at it Sunday.

Sunday. Ripped the air cleaner lid off to find the aircleaner 'blown through' and some of the concertina layers were obviously torn and and looked like they had been sucked up.

The bottom of the aircleaner box was full of sand and dried mud and the aircleaner had obviously been wet.

I am thinking that maybe the aircleaner element was actually being sucked up and occluding the air intake? It's theoretically possible but can it actually happen?

Disconnected the MAF and read the nano (engine off and cold) and the reading was 4.3 as expected when disconnected.

Measured the resistance to find pins 1-2 at 16Kohm (average I believe) 1-3 and 2-3 were unfashionably low at 5.15Mohm each-ish.

Having read many threads on the MAF, I suspect it's buggered. I haven't driven it with it disconnected or connected and won't until I replace the aircleaner. More to follow.

Ok, off to source a MAF.

Cheers
Ralph

**justinc** · 24th February 2013, 07:45 PM

The MAF could be easily damaged by bits of airfilter, there are 2 tiny wires on the actual sensor that pokes out into the airstream, IF a small particle touches one at speed it will damage it. They are so brittle that you can't even touch them with a cotton bud to clean them.

Either way the '0' figure tells the story....

JC

**jibbut56** · 24th February 2013, 08:36 PM

you can get the mas from gb cheaper than aus.
about 130 landed against 300 in aus.

**Steve Td5 130** · 24th February 2013, 11:43 PM

My wife's also had a MAF sensor fault ( low airflow ) and was using more fuel than normal and surging from 2000rpm and up making it difficult to reach 110 kmh.
I have since discovered that the Wastgate Solenoid was faulty.
( no fault code in ECU )
Have since spoke to my landrover Mechanic which has told me that he has had a number 1999 - 2001 Discovery 2 coming in with the same problem.

Temporary Repair until I can get the new Solenoid. $75.00

I have since bypassed the Wastgate Solenoid by turning the vacuum hose from the Intercooler pipe back onto the solenoid and putting a vacuum hose from the Wastgate to the Intercooler pipe.( same as a Defender Td5)

The only code to show now is Turbo over boost.

Talking to my mechanic i could manually adjust the wastgate to turn the boost down.

Hope this helps

Steve

**OffTrack** · 25th February 2013, 11:14 AM

The main symptom of the modulator failure is overboosting. It's not usually enough to trigger a fault but you can see it in the inlet manifold pressure readings. When the boost pressure exceeds 22psi the ECU intervenes to protect the engine. As part of the process inlet pressure is set to 100.00kpa which makes it easy to identify events where the ECU is limiting due to overboost.

cheers
Paul

**Ralph1Malph** · 26th February 2013, 07:02 PM

Originally Posted by jibbut56

you can get the mas from gb cheaper than aus.
about 130 landed against 300 in aus.

One of my fave suppliers quoted me around $250 for genuine replacement.
I didn't think that was too bad.

How does one know a product is genuine?

On a separate note, I am also looking at a replacement MAF sensor (without housing). I am told by folks on the VW forum I am also a member of that many bosch airflow sensors share the same characteristics.

I'll see how I go.

Ralph

**OffTrack** · 26th February 2013, 07:18 PM

Originally Posted by Ralph1Malph

One of my fave suppliers quoted me around $250 for genuine replacement.
I didn't think that was too bad.

How does one know a product is genuine?

On a separate note, I am also looking at a replacement MAF sensor (without housing). I am told by folks on the VW forum I am also a member of that many bosch airflow sensors share the same characteristics.

I'll see how I go.

Ralph

Genuine are VDO/Siemens parts but come in a box with a LR sticker.

**Roverlord off road spares** · 26th February 2013, 08:43 PM

Originally Posted by OffTrack

Genuine are VDO/Siemens parts but come in a box with a LR sticker.

Correct, and OEM vdo /seimans ones don't come with L/R stickers and cost less.

**OffTrack** · 26th February 2013, 09:56 PM

Originally Posted by Roverlord off road spares

Correct, and OEM vdo /seimans ones don't come with L/R stickers and cost less.

Which makes buying OEM a no brainer.

**Ralph1Malph** · 27th February 2013, 06:40 PM

By Joves I think I am onto something!

Could one of you knowledgeable chaps have a look at the files and give advice?

In the 'disconnected' file, lines 61 through 66 are interesting as they show manifold turbo pressure dropping to 100 from 235 ish. I have read that this means I'm overboosting and the ECU is compensating by setting to 100 to avoid damage?

It only appears once in the other file, but I suspect that was more to do with the sampling rate. The surge is pretty quick.

Of note is that I have an EGR bypass fitted and the short route I drove to get this data has many turns and hills. Basically around the block so a bit stop start.

So....what bit is knackered? What should I change next? Juries still out on the MAF sensor......

Ralph

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