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Discussion Starter #1
HI
I have a common problem with my Brera, misfiring. During checking injectors I've found odd readings,
hot engine 850 rpm:
#1:-2,52
#2:5,10
#3:4,04
#4:-1,96
#5:-4,78,
target mass air flow 464 mg/i
measured 655 mg/i
2000 rpm:
target mass air flow 850 mg/i
measured 450 mg/i
What do you guys thinking about this? where is the problem MAF or timing belt? or both?
 

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Why would you think cambelt? There are so many other possibilities! Boost leaks from hoses or swirl flap pivots or detached actuator bar, or carbon-choked MAP sensor, for instance.

MAF can be tested by disconnecting the electrical connection. The car will idle rough and temporarily show an error but should improve at higher revs if MAF is defective.
 

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Discussion Starter #3
Sorry I didn't mention here but my car is deflapped, DPF is removed, EGR blanked, remapped. Why cambelt? because during removing inlet manifold for deflapping I could change the cambelt position. Due that job I've cleaned MAP sensor, checked for leaks, sealed one on connection plastic pipe-turbo. I will try test that MAF as you said.
 

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OK. I guess you need to check the cam timing then. Easy if you have the alignment tools. But I think the MAF is more likely to be the explanation. Looking at the numbers maybe the turbo is over boosting due to sticking vanes. There should be about 20mm movement at the end of the actuator lever, which should move right back to the stop under strong finger pressure. Better, test the actuator movement is smmoth and full range with a vacuum pump.
 

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Discussion Starter #5
I've checked today overboost pressure, mbar:
low rev:
target 1100
measured 1040
2000 rev
target 1150
measured 1450
What do you think guys?
 

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Discussion Starter #6
Hi
I think I've found a guilty. I disconnected MAF sensor and I had exactly this same readings for target and measured air mass in mg/inject as above and i did not received any errors. Can you just assure me in my suspicion?
 

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With a good MAF target and measured airflow will be very similar in my limited experience. But it is odd that you do not have any MAF error codes either connected or disconnected. I don't understand that.
 

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With a good MAF target and measured airflow will be very similar in my limited experience. But it is odd that you do not have any MAF error codes either connected or disconnected. I don't understand that.
My GT may be experiencing a problem with duff maf readings, but with no error codes. Its in the garage at the moment waiting for a new maf. Maybe you only get error codes when the readings fall out of a certain tolerance?

(When I unplugged it I got 2 error codes as you would expect)
 

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Discussion Starter #9
With a good MAF target and measured airflow will be very similar in my limited experience. But it is odd that you do not have any MAF error codes either connected or disconnected. I don't understand that.
Maybe because I disconnected on running engine?
BTW I've found odd misplacing, I have installed MAF with Bosch number 0281002764 but I've found out it should be 0281006048( I think...)
 
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