Volvo FMX V4 Euro6

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Sharpy
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Volvo FMX V4 Euro6

Post by Sharpy » Sat Nov 30, 2019 2:35 am

Well I know there are a few of you out there interested in using the Pico on trucks so I thought I'd share my process with this one as I have done a few of these now and Pico has definitely improved the accuracy and speed of the diagnosis with them.
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The truck is a 2016 Volvo FMX Tipper with the D11k engine, the truck come to me after the customer has spent thousands in the last 2 months with another workshop changing different parts trying to get to the bottom of the fault which continually puts the vehicle in limp mode and displays an engine system failure warning on the dash, this customer is completely new to me and I was recommended by one of my customers so the pressure was on to get it right first time. :roll:

So when the truck arrived a quick check of the dash showed the engine fault message was on so a scan of the engine revealed 2 codes both current which were P228F00 and P009400 both of which relate to fuel pressure the first one basically means the fuel pressure regulator has reached its limit in trying to control rail pressure and the second is saying there is a fuel leak, the ecu determines a leak by monitoring the rail pressure at engine shut down and although I have yet to see it written down I believe 40 seconds or more is regarded as acceptable for fuel pressure decay on shutdown.
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So due to the ecu not giving a data pid for Rail Pressure even in the dealer tool the only realistic way to monitor the pressure is with a scope and as the rail is mounted under the cam cover with the injectors I back probe the harness where it enters the cylinder head.(circled below)


Once I take a base reading with a start idle then shut down to confirm the decay time is excessive then I set about removing the air box with its frame and then the cam cover to get access, in this case the decay time was less than 4 seconds which is by far the worst I have seen.
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Fuel Decay all cylinders 3.7secsx2.psdata
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Once we have access you can get a sense of the fuel system fitted, on the rail you have the pressure sensor at the rear and the ecu controlled pressure regulator (ePRV) at the front, the 6 injectors are made up of 2 different types cylinders 1,3,5 have standard solenoid injectors and 2,4,6 are pump unit injectors that supply the rail, the return is via a common galley that runs through the head.
My next step is to disconnect the injectors 1 at a time and cap the rail and redo the decay test each time and once a bad injector is disconnected from the rail the decay time should improve and then after checking them all it can be established which ones are leaking back the most, also whilst checking the pump units aside from the cap on the rail a pipe is connected to the injector to allow the fuel to be pumped into a container besides stopping the sump being filled with fuel its helpful to compare the flow rate from each pump unit.
After checking all 6 normally it would be obvious from the results which injectors are responsible for fast decay time but in this case the decay remained the same regardless of which injectors were disconnected.
Only shown with no 1 disconnected as all captures pretty much the same.
no1disconnected.psdata
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Next it was time to establish what else could be leaking high pressure fuel from the rail and apart from a physical leak from the rail or pipework which is all ok the only other culprit could be the ePRV which normally would be checked before the injectors but as this was one of the parts already replaced I decided to leave it till last, this was done by capping the cylinder head where the pipe from the ePRV enters the return passage and then fitting a larger bore reinforced long hose to the pipe and routing it to a container this was done to reduce pressure in case anything did escape from the ePRV but it didn’t even shed a drop even at ignition off yet the decay time was still around 4 seconds.
fuel regulator disconnected decay 4 secs.psdata
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Even though I have done this quite a few times this is the first time I have been unable to improve the decay time during the tests which did confuse me a little at first, I was trying to figure that if even all 6 injectors were indeed the cause then surely disconnecting any 1 of them would have a positive effect on my test. At this point I decided to step away and get on with some other jobs that were waiting whilst I thought about what could be happening and with all the results saved I could go back and review it later.

As it turned out I ended up among other things on a similar truck that turned out having a broken Can wire that I used the Pico to track down but it meant I didn’t get back to the fuel issue that day and it wasn’t till I was in the bath when I got home that I realized I had everything there in blue and red 😉 it could only be all 6 injectors because there was no other way for the pressure to escape the rail and the consistency of the waveform confirmed the rail pressure sensor was good and also new lol.
The only reason I could think of to explain why isolating injectors didn’t improve things was the galley in cylinder head was backing up with all the fuel leaking off so by disconnecting only 1 at a time wasn’t enough in this case.
As soon as I got in to work I ordered all 6 injectors which were just over £2k and set about removing the old ones which is quite involved compared to most.
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Once back together and the trim codes and adaptions had been reset a quick check showed that the fuel pressure was still holding after 3 mins which is why in this capture It doesn’t start at 0.5 volts because there was still pressure from the capture before that I hadn’t saved.
Fuel Decay good after repairs.psdata
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A long road test confirmed the symptoms were gone and the customer collected the vehicle and its back out hauling muck where it belongs with me not having to worry if we fixed it as thanks to my Pico I know we did!
Last edited by Sharpy on Fri Dec 06, 2019 7:04 pm, edited 1 time in total.

ronw38
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Re: Volvo FMX V4 Euro6

Post by ronw38 » Sat Nov 30, 2019 8:56 pm

Good job Sharpy, with product knowledge, sticking to basics and the aid of a good scope you nailed it
RonW

ben.martins
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Re: Volvo FMX V4 Euro6

Post by ben.martins » Wed Dec 04, 2019 1:05 pm

Excellent job Sharpy. We've all been there where the mind is ticking away long after we've left the job but this will no doubt help others out in the future.

Great stuff, keep up the good work and I'm sure we all look forward to the next one! :D

AndyM535
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Re: Volvo FMX V4 Euro6

Post by AndyM535 » Fri Dec 06, 2019 12:24 pm

What sort of thing would cause all 6 injectors to fail? Bad fuel or a broken down filter?

Sharpy
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Re: Volvo FMX V4 Euro6

Post by Sharpy » Fri Dec 06, 2019 7:00 pm

I'm not entirely sure but its definitely a very common issue, Another one of these I have worked on also a 65 reg has had 18 injectors since new. I was considering trying a freedom of info to try and find out just how many have been replaced compared to the out going euro 5 model as I have probably changed not even 6 injectors total on Eu5's as failure of those was extremely rare and if you did have one go it was never more than 1 although the injector sleeves were quite common.
Crazy they could get things that good to this system which I think is a terrible design.

The 13Litre D13K Euro6 doesn't seem to suffer with this either but that system doesn't use the commonrail and uses 6 pump units much like the euro 5 did.

Thanks for all the positive comments

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