X-Type ( X400 ) 2001 - 2009
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Mass Air Flow

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  #1  
Old 07-30-2013, 02:09 PM
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Default Mass Air Flow

Hi All
I've got the flashing glow plug warning light, limp mode blues, when it happens it's always on start up, usually cold and it often resets after switching off then on again. I invested in an ELM 327 Diagnostic Scanner which when used in conjunction with a laptop is a handy £15 worth of kit but it tells me that there are no recorded faults, even when the fault is active. Looking through the data I noticed that the Intake manifold pressure and Mass air flow values are all all over the place on start up and idle then settle down at higher revs.
If anyone has used a similar tool and knows if this is normal or not I'd be grateful of any feedback. All being well I intend to attack the EGR valve tomorrow so we'll see if that makes a difference.
Thanks
Pete
 
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Old 07-30-2013, 04:19 PM
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PDMiller, since you mention the glow plug, you must have the diesel X-Type. My experience with diesels is very limited (I mainly get to play around with V16 diesels like they use in train locomotives), but I do know enough to be dangerous. The air flow bouncing all over the place tells me that you most likely have an issue with the MAF sensor or the associated wiring. I would try cleaning the MAF first and then seeing what you have. This will also give you a chance to look at the wiring to make sure it is not damaged. Then lets see what you have at that point.

Please keep in mind that your car does not have a restriction in the intake like what a gasoline engine does. So, for the air flow to jump around, that can only occur if either 1) the engine RPMs are jumping erratically up and down, or 2) the MAF sensor is having issues and it is seeing erroneous air flows. The only other thing that I could think of that would possibly do something like what you are saying is having a stuck shut exhaust valve. But, I am sure you would know that as the motor would be significantly down on power.
 
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Old 07-31-2013, 02:06 PM
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Thanks for the reply Chris. I took the exhaust recirc valve out today and it was about 50% restricted with carbon but it wasn't jammed so after a good clean I put it back. Checked the MAF sensor and wiring while I was at it and the turbo guide vane actuator which seems to be doing what it should do. I used the car all day and so far so good, no flashing light but time will tell. I'll put the scanner back on and see if my efforts have made a difference.
Cheers
Pete
 
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