Volvo FMX V4 Euro6

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Sharpy
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Volvo FMX V4 Euro6

Post by Sharpy »

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
(3.53 MiB) Downloaded 149 times
InkedIMG_3548_LI.jpg
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
(2.91 MiB) Downloaded 143 times
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 »

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 »

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 »

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 »

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

carl456
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Re: Volvo FMX V4 Euro6

Post by carl456 »

Hi Sharpy, Hope you don't mind me chiming in on this one.

The two codes you have both have TSB's for them, if you like I can email them to you for the future?

The pressure drop spec is 25 seconds so 4 is definitely not good!

The ePRV is in fact a pressure relief valve not the mentioned pressure regulator in the DTC. The pressure regulator is contained within the pumping injectors so you have 3 in total, one in each pumping injector. Regulator no.1 refers to injector no.2 I believe.

Comparing fuel output from the pumping injectors while not under any load can not be trusted, typically this code sets in a high load situation where the pumping elements in the injectors leak. If you have two leaking pumping injectors blanking off the rail like you did will see equal results across all injectors as you only have one blanked off at one time. The fuel galley in the head will not back up, it goes back to the tank.

There is a very simple and fast way to determine a leaking pumping injector on this fuel system.By using your scope you can look at fuel rail pressure in enough detail to see a leak within a single pumping
injector. As you can see the pressure drop is quite evident on this injector, by syncing with an injection event
you can determine which pumping injector is at fault although it is recommended to change all 3 pumping
injectors when one fails.

I hope you don't mind me posting this and that it helps in the future. Any questions just ask. Give me your email and ill send you the TSB info.

Carl
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Sharpy
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Re: Volvo FMX V4 Euro6

Post by Sharpy »

Hi Carl

This info is awesome and definitely welcomed, most of my knowledge on this system is just what I have learned along the way plus some help and info from a friend at Volvo and some great general advice from PicoBen. Any additional info and details are always appreciated and the regulator within the pump injectors explains a lot and seeing the detailed layout of your capture would certainly speed up diagnosis on the next one which is what this forum and Pico is all about.

In regards to the return I realize it goes back to the tank but I wondered if it was overcome by the excess leaking would the galley be able to cope and maybe back up but your description of the pump units regulators would explain that much better.

Many Thanks

Lee

carl456
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Re: Volvo FMX V4 Euro6

Post by carl456 »

No problem Lee, hope it helps.

I'm sure you are aware of the camshaft issue on these too. I haven't proved it yet as I didn't scope one with a shifted cam but i'm thinking you might be able to see a retarded or shifted cam shaft lobe on the pumping injectors with this method too by looking at pressure rise, or lack thereof, as the injector regulator is shut. Again its just a theory, if I get one with a bad cam ill scope it and post it here if its of any use.

Keep posting your case studies, nice to see someone else on trucks using Pico, there's not too many of us.

Carl

Sharpy
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Re: Volvo FMX V4 Euro6

Post by Sharpy »

Oh yeah you could say we've seen a few cams lol, we had one on a Renault recently where the lobe was spinning free on no 6 pump unit and the rocker bridge for the exhaust valve had smashed the top of the pump unit and the funny thing was they had bought it in after they had replaced no.6 injector yet the fault was the same for some reason, I should have a capture of the fuel rail pressure saved I'll have a look :mrgreen:

found it
Attachments
Renault_C_2016_Diesel_frpsyncno1.psdata
(16.68 MiB) Downloaded 123 times

Sharpy
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Re: Volvo FMX V4 Euro6

Post by Sharpy »

As a little follow up on this I have had the customer return this week and all has been well with the truck since the repair so he is happy, so much so he has bought the sister truck in with similar symptoms but this time before a fortune was spent although he had someone local take a look and they replaced an oil control valve and the symptoms remained so he bought it to us. A scan revealed the same fault code as the last truck which was P228F00 I'm unsure why the oil control valve was replaced I can only assume a different code was present which was then cleared :?

This time using info from Carl's post above I added a sync to no.1 injector and got this capture,
Fuel decay and inj1 sync 2 x 6secs.psdata
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the decay time was less than 6 seconds but more interesting is using the sync you can see the 6 pulses from the 3 pump units and after the peak of each pulse the pressure is clearly dropping sharply before the next pump unit raises the pressure again
fuel pressure before.png
Now using Carl's info I could see that either all 3 Pump units were gone or there was a leak from elsewhere on the rail so I then removed the Airbox and rocker cover so I could access the rail, I decided to check the ePRV first and straight away I had fuel escaping into my container from the outlet on the ePRV so I swapped the valve with a known good one I had from someone else's parts cannon shrapnel :D

This is the capture I got Straight away the decay time increased to more than 1 minute but I wanted to see how the pulses looked
fuel pressure with known good.png
The difference is clear to see and I ordered a new one straight away with full confidence it was all that was needed, the new one was fitted and I took another capture so I could be sure there would be no issues before fitting the rocker cover and air cleaner back before a long road test then a call to a happy customer as I think he was expecting a big bill.
Fuel decay and inj1 sync eprv replaced.psdata
(10.07 MiB) Downloaded 98 times
Thanks to Carl for your input and helping me see the wood through the trees :lol:

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