New MAF time

M80

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Limp mode and Torque reports the MAF performance is the problem,
strangely I can't find confirmation with the iCarsoft Vll, maybe I need to learn that tool better, but with auto scan I would expect the fault to come up.

Pieberg used to be the MAF of choice if I remember but Bosch has been fitted since 2014 and that's what comes up with eBay searches.
I'll ring MB for confirmation on the morrow, are their prices for these usually bank emptying?
 

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Limp mode and Torque reports the MAF performance is the problem,
strangely I can't find confirmation with the iCarsoft Vll, maybe I need to learn that tool better, but with auto scan I would expect the fault to come up.

Pieberg used to be the MAF of choice if I remember but Bosch has been fitted since 2014 and that's what comes up with eBay searches.
I'll ring MB for confirmation on the morrow, are their prices for these usually bank emptying?
Ring MB Grangemouth 01324 686002 and it will be less painful....
 

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Ring MB Grangemouth 01324 686002 and it will be less painful....
They were having phone issues today and couldn't put you through to Steve. I emailed him and am waiting a call back...
 

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Nope... Steve's direct one you posted a while back (I had to do a forum Search).
 

John Laidlaw

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Nope... Steve's direct one you posted a while back (I had to do a forum Search).
I should have mentioned he asked to use the Grangemouth parts one I posted above and just C.C. him in the future as he’s not always picking up his mails - that way his team will pick up...sorry about that!
 
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I didn't try Grangemouth as I'm hoping to drive down to London tomorrow so ideally would like to sort it today.
MB Macclesfield quoted £307.20, not in stock so would need to order anyway.
A drive to Sheffield, in limp mode, and if in stock would be £76ish, I didn't check.

The local motor factors should be able to have a Bosch unit by this pm for £126.35,
this matching the part number gained from MB, and is nothing like the number I found on the 2014 unit in place.

MB Macclesfield = crazy price.
Local Motor Factors = high price, but convenient so I've ordered with fingers crossed.
 
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So not the MAF, unless the new one is also goosed - doubtful.

I did get iCarsoft to confirm the fault, it will reset the fault code, extinguish the MIL, but informs me that although there is reset the fault is still there.
It still runs in limp with either MAF.

Any thoughts appreciated.

Grabbing at straws but 'just' prior to this I had the front bumper off. While I've disconnected and then reconnected front parking sensors, temperature sensor and the two electric fans I fail to see how I might have caused this MAF fault.
Usually when something goes T's up after some intervention I would go back go back over the steps of the intervention to discover what I've screwed up, I can't see it here though but hoping I've missed something that I've done wrong.
 
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Thanks LK,
I'll check that this morning.

A though as my head hit the pillow last night,
front bumper / intercooler.

If I've disturbed the intercooler, allowed air to pass that would cause limp. would it possibly cause the MAF fault?
 

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How’s it run with the MAF disconnected ? It’s unlikely as you say to have 2 x bad MAFs but might eliminate that at least . Is the air box in decent condition?
 
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I'll try disconnecting,
air box fine, filter ok.

A 15 mile run to drop Larisa off.
Intake pressure between 13.9 to 14.6 psi,
air intake pressure started at 16 degrees (ambient) rising to max 20 when stationary and dropping back a little while in motion.
I'm assuming these 2 readings are from within the intercooler.

Seems they are as 'I' would expect with the intercooler disconnected, so that's first point to start.
 
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It runs the same with MAF disconnected.
I've eliminated the intercooler, removed and filled with water it retained it overnight.
I did the same with the AC condensor, the AC has never worked, re gassed, lost it, the condensors are known for being holed by stones. Not this one it held the water also.

EGR was replaced a couple of months ago, that would bring up different codes as it did when faulty, and wouldn't restrict the flow anyway.

There are 2 units left on the pipework rising from the intercooler o/s. One I assume to be the tmeperature sensor, the other is similar size to the EGR any pointers as to what it is / does? For some reason I can't attach a photo.
When revved I could hear a whirring, not the sound you might associate with a ruptured intercooler.
 
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Thinking aloud, well in print.

Code tells me there is a MAF performance issue, Viano goes into limp home mode.

Temperature and pressure look to be reading reasonably, certainly not wild readings as a faulty unit might give. I'm assuming these readings are from the intercooler output pipework.
There is another sensor in the air filter box, output side. I'm assuming to be pressure sensor. Not sure what it would affect or how to monitor it.

Resonator is just a muffler as I understand, not removed but unlikely to be blocked as it only passes post turbo air.
Intercooler tests as water tight.
Butterfly valve on post intercooler pipe work moves freely, the pressure and temperature sensors here are as mentioned previously, assumed.

Onto the manifold with EGR enroute. EGR moves freely.
Inlet flap mechanism moves freely, if the ports were clogged, or flaps collapsed I would expect resistance.

If I'm right with my thinking the only things untested are the resonator and the air filter pressure sensor. I'm not expected the resonator to have issue and if the pressure sensor was u/s wouldn't I expect a fault code for it?

I'm now wondering if the replacement MAF is faulty.
 

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Thinking aloud, well in print.

Code tells me there is a MAF performance issue, Viano goes into limp home mode.

Temperature and pressure look to be reading reasonably, certainly not wild readings as a faulty unit might give. I'm assuming these readings are from the intercooler output pipework.
There is another sensor in the air filter box, output side. I'm assuming to be pressure sensor. Not sure what it would affect or how to monitor it.

Resonator is just a muffler as I understand, not removed but unlikely to be blocked as it only passes post turbo air.
Intercooler tests as water tight.
Butterfly valve on post intercooler pipe work moves freely, the pressure and temperature sensors here are as mentioned previously, assumed.

Onto the manifold with EGR enroute. EGR moves freely.
Inlet flap mechanism moves freely, if the ports were clogged, or flaps collapsed I would expect resistance.

If I'm right with my thinking the only things untested are the resonator and the air filter pressure sensor. I'm not expected the resonator to have issue and if the pressure sensor was u/s wouldn't I expect a fault code for it?

I'm now wondering if the replacement MAF is faulty.
You’d be very unlucky with 2x faulty MAFS though and it still runs bad with the MAF disconnected ?
 
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Truth is it runs well MAF connected or disconnected, but I'm unsure what that means.
Either way it's in limp so low on torque. No turbo, so uphill it's a slug but on the level it drives ok(ish).

But having checked even the resonator can the only unchecked component, air box pressure sensor be the culprit?

I did find the 'o' ring on the output spigot of the turbo damaged, but it will have been so during my ownership. If passing easily I would lose any boost but could it cause a MAF fault?
 

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I suspect this is s classic example of MAF reporting the issue but not being the culprit (a bit of don't shoot the messenger...).

I recall one of the Indies recently discussing this very scenario of MAF being called out when the problem is elsewhere.
 

John Laidlaw

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Good find LK
Just wondering out loud too if the icarsoft in this case has reached the edge of its capability and Star would interrogate better?
Does indeed seem a merry go round at the moment...
 
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Interesting reading LK, Steve certainly knows his stuff and has had my respect for a long time.
from this anyone here replacing the MAF 'themselves' will have had poor results.

There is a difference in that mine seems to run the same no matter which MAF, and connected or not. The new one which will be running on old settings doesn't run lumpy.
It occurred to me however that iCarsoft will reset the fault code but inform that the fault is still present, that being before the engine is running. So it isn't monitoring performance at that point but seeing an out of range sensor. Removing the signal line sounds like it would do that.

It's easy to fall out with these things when it can seem MB design to lift you by the ankles and shake till your pockets are empty, as it would be for some poor unsuspecting sod stuck away from home calling on who ever they can find locally. A main agent for instance.
Sorry a bit of frustration showing there.
 


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