Diesel 131 misfire

K1AAS · 31st January 2019, 11:54

Hello,
I am hoping to get to the bottom of the 75's "Misfire".
At low RPM and under load e.g. uphill it feels like a misfire, this has now manifested itself at higher RPM.

Prior to the faults last week it has had since September:
New fuel tank pump (only one on this late car 2005)
New MAF
New pressure rail sensor
Four injectors removed and serviced all to be found within limits.

All of the above items did not resolve the "misfire"

Following a post on a forum I changed the Auto box fluid in case the low RPM "misfire" symptom was caused by the box not changing down to a lower gear in time.

A couple of years ago, after hitting a pothole the engine management light came on, then went off but no code stored. Last week it did the same again, this time stayed on and a whole list of fault codes came up.

Pre-delivery pressure low
Glow plug fault
Engine Fan control
Air Flow Sensor plausibility

A T4 revealed the above, the garage removed the EGR valve and cleaned the carbon build up (the car has only ever been run on Shell V power) as this can apparently affect the Air flow Sensor.

Finally with the car linked up to a live data analyser a road test revealed the fuel pressure was dropping below the threshold at high demand. a retest restricting the return line pressure from the fuel filter solved the problem.

So it would appear it requires a new pressure relief valve after the filter, this is located in line between the battery and engine just after the fuel filter.

Reading up on the site it has been mentioned that this is a Pierburg part number 7.22920.01.0. , does anyone know if this is correct, or where one can be obtained?

Arctic · 31st January 2019, 14:40

Hi Nick.
That will be the non return valve drop Mickyboy a trader on here he maybe able to send you ones they are easy to remove and fit.

Mickyboy · 31st January 2019, 14:57

Quote:

Originally Posted by Arctic

Hi Nick.
That will be the non return valve drop Mickyboy a trader on here he maybe able to send you ones they are easy to remove and fit.

Yeah if he drops me a PM I’m sure I can sort one of them out no problem at all
Mick

K1AAS · 31st January 2019, 16:48

Hello Mickyboy,

PM sent re valve.

K1AAS · 31st January 2019, 16:50

Does anyone Know what pressure this bypass valve should open at?

31st January 2019, 11:54	#1
K1AAS Newbie 75 cdti tourer con se auto & MG ZT 260 SE Join Date: Jun 2009 Location: Colchester Posts: 16 Thanks: 1 Thanked 0 Times in 0 Posts	Diesel 131 misfire Hello, I am hoping to get to the bottom of the 75's "Misfire". At low RPM and under load e.g. uphill it feels like a misfire, this has now manifested itself at higher RPM. Prior to the faults last week it has had since September: New fuel tank pump (only one on this late car 2005) New MAF New pressure rail sensor Four injectors removed and serviced all to be found within limits. All of the above items did not resolve the "misfire" Following a post on a forum I changed the Auto box fluid in case the low RPM "misfire" symptom was caused by the box not changing down to a lower gear in time. A couple of years ago, after hitting a pothole the engine management light came on, then went off but no code stored. Last week it did the same again, this time stayed on and a whole list of fault codes came up. Pre-delivery pressure low Glow plug fault Engine Fan control Air Flow Sensor plausibility A T4 revealed the above, the garage removed the EGR valve and cleaned the carbon build up (the car has only ever been run on Shell V power) as this can apparently affect the Air flow Sensor. Finally with the car linked up to a live data analyser a road test revealed the fuel pressure was dropping below the threshold at high demand. a retest restricting the return line pressure from the fuel filter solved the problem. So it would appear it requires a new pressure relief valve after the filter, this is located in line between the battery and engine just after the fuel filter. Reading up on the site it has been mentioned that this is a Pierburg part number 7.22920.01.0. , does anyone know if this is correct, or where one can be obtained?

31st January 2019, 16:48	#4
K1AAS Newbie 75 cdti tourer con se auto & MG ZT 260 SE Join Date: Jun 2009 Location: Colchester Posts: 16 Thanks: 1 Thanked 0 Times in 0 Posts	Hello Mickyboy, PM sent re valve.

31st January 2019, 16:50	#5
K1AAS Newbie 75 cdti tourer con se auto & MG ZT 260 SE Join Date: Jun 2009 Location: Colchester Posts: 16 Thanks: 1 Thanked 0 Times in 0 Posts	Does anyone Know what pressure this bypass valve should open at?