General MAF sensor.............Faulty or not?

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General MAF sensor.............Faulty or not?

Joined
Jun 6, 2008
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Location
ireland
Hi to all,

I need some advice to ascertain if my MAF sensor is gone or not.

The car is a 2005 1.3 multijet 7 seater Doblo.

The car when started will idle fine and reach normal operating temperature good as well.

When driving however, at the lower rpm range its ok, but when you press the pedal

to increase speed it takes forever, and is unlikely to reach 60 mph.

I took off the MAF unit and gave it a good clean, which didn't appear to be too bad at all.

I disconnected the harness from the MAF sensor and took it for a spin......It went

like a bullet!!!

I reconnected the MAF sensor and it returned to its former ways, no power at

the higher rpm range.

I got out the multimeter and checked for the 12volts supply wire, along with the

ground wire location.

This particular MAF sensor has a 5 pin connection. If you were to look at the

5 wire/cable when harness is connected, the first cable on the left I number it no. 1

1 == 5volts supply wire ( for IAT sensor )

2 == 12volts supply wire for MAF sensor.

3 == Ground / Earth.

4 == Signal wire for IAT sensor.

5 == Signal wire for MAF sensor.

These are the arrangements of my use of the multimeter and what I found.

With the engine running and the back probes in place I have the following readings

when engine is at operating temperature.

At idle 1.79 volts

At 3000rpm 2.89 volts.

My question really is, should I have a wider voltage range from idle and 3000rpm.

I don't know if these figures are acceptable or not. My logic is, with more air

entering the engine at higher rpm, more fuel should enter as well. But if the voltage

readings from the MAF sensor are on the low side, the ECU will respond to

the voltage signal............even though the throttle plate is open more to allow more

air into the engine.

Without the MAF sensor connected............................It drives as though I

STOLED IT!!!

Any help would be much appreciated, and if anyone would have some idea of

voltage readings I should be getting would be great.

Just to mention I have no air or vacuum leaks from what

I can see.

Sorry for the long thread.

John.
 
Will stick my meter on my 1.3 qubo tomorrow night and see what it reads also have some figures for redoing mafs in hz at work which may be of help does sound from experience though that the maf is shot do you have the facility to look at the maf readings on a diagnostic platform aswell ?
 
Will stick my meter on my 1.3 qubo tomorrow night and see what it reads also have some figures for redoing mafs in hz at work which may be of help does sound from experience though that the maf is shot do you have the facility to look at the maf readings on a diagnostic platform aswell ?

Hi K333fer,

Thanks a mill for your reply. Some figures would be great to have.

I do have a delphi diagnostic and laptop, but the brother has it at the moment

checking out his doblo. As soon as I get it back, I'll connect it up, and see what

comes up. You're abit ahead of me when you say "redoing mafs in hz "

I take it that the diagnostics I have will show the voltage variations under

different rpms conditions.

Thanks for your comments, much appreciated.

John.
 
Hi K333fer,

Thanks a mill for your reply. Some figures would be great to have.

I do have a delphi diagnostic and laptop, but the brother has it at the moment

checking out his doblo. As soon as I get it back, I'll connect it up, and see what

comes up. You're abit ahead of me when you say "redoing mafs in hz "

I take it that the diagnostics I have will show the voltage variations under

different rpms conditions.

Thanks for your comments, much appreciated.

John.


No problem will get some readings out later , just as a note have you checked your turbo is free ? Had a c3 in work the other day everything pointed to the maf but it was the vanes sticking , went perfect with the maf disconnected aswell just remember with it disconnected it will just activate a base map , also of the turbo isn't working one freely the air flow will be lessened
 
No problem will get some readings out later , just as a note have you checked your turbo is free ? Had a c3 in work the other day everything pointed to the maf but it was the vanes sticking , went perfect with the maf disconnected aswell just remember with it disconnected it will just activate a base map , also of the turbo isn't working one freely the air flow will be lessened

Hi K333fer,

Thanks for your added suggestion about the turbo. I initially thought straight away

about the turbo being the culprit, but when I disconnected the maf, and it went like a

bullet, I thought there must be something else, like the maf sensor.

An up date. I bought the maf senor into our local motor factor, to order a new one.

I'll collect it tomorrow morning, grand job. Got back home and had a good look at

the sensor again. Bare in mind, I already gave a good cleaning, but no change.

So I gave it another blast of the maf cleaner. I did manage to get it cleaner looking

but wasn't expecting any change in performance. Wasn't I in for a surprise, it took

off like a mad man!!! Plenty of power at higher rpm range, and the turbo kicked in

immediately. It came a bit of a shock to say the least....................But a nice one.

I didn't get back my diagnostics from my brother yet, but as luck would have it, I

happen to have the MultiEcuScan and lead and spare laptop.

Connected her up, checked the voltage reading of the Maf sensor.

At idle == 2.0 volts

At 3,000 rpm == 3.0 volts.

Previous readings were at idle 1.79 volts and at 3,000 rpm 2.89 volts.

There has been a change, although small, the idle figure has jumped quite a bit.

I obviously didn't clean the sensor quite as good as I thought. Never to old to learn,

that's for sure. I like to know more about the turbo opening and closing. To be

honest, I've never tackled one before, and it would need to checked soon, just to

keep ahead of the posse so to speak. I honestly do not know if the vains are

working properly or not .Are there any pics available on this site

concerning this area? Another topic would be the EGR valve, plenty have said that

they do give trouble if neglected.

I suppose, when you think of it, the likes of the maf sensor should be checked and

cleaned, if necessary, at service intervals.

I've been lucky with this problem, the next might not be so easy, but with the help

from this site ...............................anything can be accomplished.

Thanks a million K333fer for all your help and advice.................

Next..................turbo gate opening and closing.....................please!!!

John.
 
I pulled couple readings out of mine this evening mine only has 4 wire maf but quickly got some out of obd in g/s they were 6.72 at idle and 33.93 static at 3000,
Right then turbo vanes there's around 8-10 vanes in most vv turbos as these are turned by the actuator they change the air flow/speed over the driven impeller ,
They are only small and can Seize on the pivot points and if you get one tight the rest won't move , they typically stick when hot the easy tests to prove this is either disconnect the actuator not fun when hot or with a mityvac and watch and feel for smooth operation
 
I pulled couple readings out of mine this evening mine only has 4 wire maf but quickly got some out of obd in g/s they were 6.72 at idle and 33.93 static at 3000,
Right then turbo vanes there's around 8-10 vanes in most vv turbos as these are turned by the actuator they change the air flow/speed over the driven impeller ,
They are only small and can Seize on the pivot points and if you get one tight the rest won't move , they typically stick when hot the easy tests to prove this is either disconnect the actuator not fun when hot or with a mityvac and watch and feel for smooth operation

Hi,

Thanks for your voltage readings. There is definately a good voltage range from your

readings, I was expecting something similar from the doblo, but alas no.

But having said that, the power is very good at the moment. When I collect the new

Maf sensor tomorrow, I'll put it in, and see if there is any improvement in the voltage

range.

Thanks a mill on the info on the turbo set up and principles of its operation.

The actuator, is a rod or tube, any info on approximate diameter size?

Just need to know its location in relation to the turbo.

Here is where I get lost............................what is a mityvac?

Forgive my ignorance. And sorry for loading you with all these questions.

John.
 
Hi,

Thanks for your voltage readings. There is definately a good voltage range from your

readings, I was expecting something similar from the doblo, but alas no.

But having said that, the power is very good at the moment. When I collect the new

Maf sensor tomorrow, I'll put it in, and see if there is any improvement in the voltage

range.

Thanks a mill on the info on the turbo set up and principles of its operation.

The actuator, is a rod or tube, any info on approximate diameter size?

Just need to know its location in relation to the turbo.

Here is where I get lost............................what is a mityvac?

Forgive my ignorance. And sorry for loading you with all these questions.

John.


The actuator is the vacuum unit with the small rubber pipe on it that is connected to an electro valve that works via a pwm ( pulse width modulation) signal from the pcm , I have a set of vanes from a t5 stripped out at work on our rouges gallery will take a pic with a size guide tomorrow for you , a mity vac is a hand help vacuum and pressure pump one of the handiest things you can have in your arsenal also good for tuning carbs with , it's no problem at all
 
The actuator is the vacuum unit with the small rubber pipe on it that is connected to an electro valve that works via a pwm ( pulse width modulation) signal from the pcm , I have a set of vanes from a t5 stripped out at work on our rouges gallery will take a pic with a size guide tomorrow for you , a mity vac is a hand help vacuum and pressure pump one of the handiest things you can have in your arsenal also good for tuning carbs with , it's no problem at all

Hi,

I've just spent the last couple of hours on you tube getting familiar with turbos and

waste gate valves, and how they all work together. Very interesting, the examples

I've looked at so far, have been with a mechanical valve operation, which in turn,

operates the diaphragm, which then opens the waste gate to directs exhaust gases

away from the turbine to reduce boost pressure. If I understand you correctly,

this valve is electronically operated via the ECU. Hope I have this right. Its now all

piecing together, an examination of the turbo and there operating arms and linkages

would be very useful to see their conditions.I had seen earlier today via multiecuscan

boost pressure, but to be completely honest with you, I would not know if the figure

is within range or not. That'll be for another day I think.

Thanks for telling me about the infamous MITY VAC. I don't feel so stupid now.

Must get one!!! I owe you one K333fer, without your help, things would have been

harder to deal with. Feels great to know far more, in such a short period of time.

Thanks a million.

John.
 
IMG_1472847387.368488.jpgIMG_1472847452.642944.jpg
Apologies for the delay here's the pictures of the vanes I said about
 
Hi K333fer,

Thanks a million for the pictures, much appreciated.

I believe this system type is more efficient than the wastegate type, which so happens to be

on the doblo 1.3 multijet 2005 model.

Thanks for the info K333fer.

John.

to have the latter arrangement.
 
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