Do I Really Need A New Mass Airflow Censor?

[newland1]

My Galaxy has begun to play up. Usually after about fifteen minutes of driving it sounds and runs rough, but five or ten minutes later, at a steady speed, it clears up. Sometimes if I go straight onto the motorway, it doesn't play up at all. Other times, if I'm stopping and starting in heavy traffic, it won't clear until I switch the engine off, leave it for a few seconds and restart. After this initial hiccup, it will run perfectly well all day - I have driven for a further six hours without any problem at all. My local garage initially suggested a new air flow censor, but after plugging it into his computer and finding no evidence of a fault, was a bit more doubtful!!

Any suggestions welcome!

 

Ian

[seatkid]

My Galaxy has begun to play up. Usually after about fifteen minutes of driving it sounds and runs rough, but five or ten minutes later, at a steady speed, it clears up. Sometimes if I go straight onto the motorway, it doesn't play up at all. Other times, if I'm stopping and starting in heavy traffic, it won't clear until I switch the engine off, leave it for a few seconds and restart. After this initial hiccup, it will run perfectly well all day - I have driven for a further six hours without any problem at all. My local garage initially suggested a new air flow censor, but after plugging it into his computer and finding no evidence of a fault, was a bit more doubtful!!

Any suggestions welcome!

 

Ian

A faulty MAF Sensor would not produce rough running symptoms, only restricted power (slow acceleration and limited top speed).

 

You have not given enough details about your car (engine variant, model year etc) to comment further.

[DaveM]

Ian

A faulty MAF Sensor would not produce rough running symptoms, only restricted power (slow acceleration and limited top speed).

 

 

My faulty MAF produced flat spots and rough idling at tickover... I thought these are 'rough running symptoms'

But maybe that's because mine is a petrol engine (Dec'98 2.8 V6)

[seatkid]

My faulty MAF produced flat spots and rough idling at tickover... I thought these are 'rough running symptoms'

But maybe that's because mine is a petrol engine (Dec'98 2.8 V6)

The MAF sensor does not affect air/fuel ratio - that is the job of the lambda sensor. Your rough running at idle is 99% certainly due to the disconnected pipework.

[newland1]

My faulty MAF produced flat spots and rough idling at tickover... I thought these are 'rough running symptoms'

But maybe that's because mine is a petrol engine (Dec'98 2.8 V6)

The MAF sensor does not affect air/fuel ratio - that is the job of the lambda sensor. Your rough running at idle is 99% certainly due to the disconnected pipework.

 

Sorry, I should have mentioned that my galaxy is the 1.9tdi version on an 02 plate - minor details!! The rough running reminds me of a time when I hadn't replaced a clip correctly when changing the air filter, (throaty sound, lack of power and uneven idling) so I immediately checked every air and fuel pipe in sight. The garage did the same, but apart from a slightly loose pipe on the turbo found nothing and after tightening the turbo pipe the fault remained.

 

Ian

[Smilge]

A simple way of finding out whether or not the MAF is at fault here is to disconnect it electrically and drive it. If it appears to improve then the MAF is at fault. Just because it doesn't throw any faults up doesn't mean it's serviceable. The other sensor you might like to consider is the MAP or TMAP sensor which is basically an inlet manifold vacuum pressure sensor. These can cause problems similar to yours particularly as it appears yours is temperature related, it might be worth checking the engine temp sensor as well.

[wicpp]

I am also facing Lack of Power problem and my ford galaxy is driving in limp mode. I drives very good up to 50 but then it becomes very difficult to increase speed and now it never goes above 70.

 

I have been able to find one fault code that is P1550. And the fault is consistent if I clear it and driver my car for 5 minutes it comes back again. The fault code details are as follows:

 

17958 - Charge Pressure: Control Deviation

P1550 - 35-00 - -

 

I have cleared all the fault codes and detached my MAF sensor and then driven the car even then I see this fault along with another fault code P1144 which means MAF is detached so the fault comes even without MAF. Considering all this most probably MAF is ok and vacuum hoses are leaking or valve N75 is faulty. But now the problem is I do not know the exact location of vacuum hoses. From TIS I can not find detailed procedure to replace vacuum hoses. All I can find is that some end of vacuum hoses is attached to Air Filter Box and the some end is attached to Turbo Chargers and I think that valve N75 is under Fuse Box and I think that vaccum pump itself is behind some indicator light. Can somebody here give me the pictures telling the exact location of vacuum hoses and valve N75? I will be very thankful if somebody can point me to procedure of replacing vacuum hoses in TIS? And from where I can buy N75 for my ford galaxy?

 

I have posted this problem in form "Lack of power" but due to no reply I have posted it here as well.