Technical Ducato 2.8 JTD engine "knocking"

[Janisto76]

I'm bit surpriced about these news or diagnose. If you have petrol engine, knocking is caused by too weak air/fuel mixture (let' not talk about timing). With diesel-engines situation is opposite and this effect is caused by too rich mixture.

I also tried some kind of tuning box of my friend and the noise got louder. I think that box is "bad one" and it increases fuel pressure. It's dangerous. When I had the problem, the sound came somewhere near 2500 rpm. I don't remember speed, but it doesn't matter. When I called to diesel service, they asked me to avoid these rev speeds. Despite of these comments, I'm lucky to hear more about this, if you decide to give a shot.

They had difficulties to find the problem, because pressure looked to be ok, when looking it from computer. Still they assumed that it might be the reason and they wanted to try a new component. This is not a common problem.​

 

[Baggiz]

Aha, seems our problems aren't exactly the same then, since you had the knocking at a certain rpm and was able to avoid it by driving on different rpm:s. For me the knocking is there at a wide range of rpm:s and as I wrote now also at higher speeds on lower gears. The only way of avoiding it is to either increase/decrease the speed, or drive fast/uphill so that the engine load increases.

 

[Janisto76]

The sound started when engine was running about 2000 rpm and ended about at 2500 rpm or when pushing "pedal to the metal".

 

[Bob12345]

I realise this is an old thread but it comes high on search for this exact problem and I thought I'd share my solution.

My fiat 2.8 jtd diesel had an engine rattle, almost a pinking noise between 2,000 rpm and 2,500 rpm under load the noise disappeared if I lifted off the accelerator.

I found a broken offside bracket on the steel water coolant pipe that runs across the top of the engine, this was the source of the noise. Evidently it is a common problem on these engines, fiat went for steel to simplify manufacturing of the engine so it can be replaced with suitable rubber hose supported by the defunct steel pipe left in place.

This rpm range must be where the engine harmonics create the most vibration, I would say if the above is not your problem thoroughly inspect everything attached to your engine for tightness.

Hope that helps someone out.

 

[Communicator]

I think that @FreeSpirit has mentioned fracture of pipe as the most common cause of 2.8 JTD failures in Australia.

Possibly due to their bumpy outback roads. Perhaps you were lucky that it was only the bracket.

 

[Bob12345]

I think that @FreeSpirit has mentioned fracture of pipe as the most common cause of 2.8 JTD failures in Australia.

Possibly due to their bumpy outback roads. Perhaps you were lucky that it was only the bracket.

Yep I'm on the road at the moment so it's bodged. When I get the chance I'll be replacing it with rubber all the way through.

 

[RalphM]

Does the knock sound like it is one cylinder or all, if one and you
are getting low fuel rail pressure I would suspect a injector, if you
can hear the knock at tick over use a screwdriver as a stethoscope see
if you can narrow the noise down, a rod bearing knock will often
be loudest as you lift of the accelerator as the piston looses the
cushioning effect of the cylinder pressure.
A injector leak off test may a bad injector, look on U-Tube.

 

[corsedanny]

Hello!

Quite an old topic I see, but a very interesting one. I own a 2.8jtd from 2002, a hymer motorhome (No catalytic conv. or EGR, thank god). Great engine when it runs well, but I think I can say that I have had the same issue for a long time. So, not knowing whether people will still react on this topic, but I can at least give it a shot.

The symptoms:
- After a cold night, or a 3+ days of not starting the engine, the engine runs usually smooth as silk with a lot of power in all the rev range?
- The warmer the engine gets, the more rattling starts to occur, indeed disappearing when applying more than 75% throttle or doing not more than about 20% throttle.
- Car feels much less torque and consumption gets higher, higher than it should be.
- It feels like the car had a 'dead zone' in its throttlepedal range?
- When the rattling appears, you can 'solve' it by applying much more power or lift off and let it accelerate slower?

I drive a Swedish car, and this car had a 'powerbox' installed before. (I removed this) the symptoms became just less noticable but stayed exactly the same. Which gave me the indication that it has something to do with fuel..

I connect the car to MES and cant basically find anything wrong. Also is the car in a very very good state under the bonnet, I have absolutely no oil consumption. The only thing i cant seem to read out (As far as I believe, its the ECU refusing to present me this data) Its the message i get in AlfaOBD at least.. is the fuel temperature. Now I have disconnected the fueltemperature connector and I do not notice any difference in running.
Also all pressures (incl common rail pressures) are up to what they should be according to MES.

The only thing I noticed is that I have track two of my throttle pedal potentiometer often spiking down to 0v. But I refuse to believe that this has something to do with the rough running to be honest.

Often the connector from the throttle pedal potentiometer is giving issues, I have soldered through these cables. Without any noticable difference.

So the weird part is, that I sometimes do notice difference when i drive the car over a short bump in the road.

Also when I let the car idle a long time, (6-10 mins) and start driving again, the car behaves much much better for a short while. When the fuel tank is almost empty.. the rough running get worse, when I then fill up completely.. the rough running disappear for a big part again.

Do your symptoms relate to what i described here? And have you perhaps solved it already?

Now I suspect a fuel starvation issue for a longer time already. And I know from a very well known and good Dutch Italian car software specialist that told me that there are 6 different software versions for the 2.8jtd and especially 1 really sucks.

The rattling you guys describe.. i can now be sure for a 100% that it only happens when the Pilot injection is active. Thats why when you apply full throttle it stops.. cause this pilot injection is only active in certain circumstances. I think that this is a big clue, and I am trying to get an answer still if the rattling can occur when there is a fuel starvation (most likely caused by the software when fuel gets warm) that especially the pilot injection is starting to make noise.

Also as the symptoms are quite much worse with a empty fuel tank compared to with a full fuel tank.. an empty fuel tank is much more easy to make all the remaining fuel to become hot? Fresh new fuel never has this temperature and therefor it runs much better for a while again?

So.. fuel temperature being the issue? How come that I cant read out specifically this sensor from the ECU? That it keeps saying 0 degrees or with Alfaobd 'ecu refuse request' or something like that. Is the ECU of the 230Duc 2.8 not calculating in this factor with quantity and timing of the injection?

Do your symptoms relate to this?

Greetings,
Danny

 

[gonzo1]

Hello!

Quite an old topic I see, but a very interesting one. I own a 2.8jtd from 2002, a hymer motorhome (No catalytic conv. or EGR, thank god). Great engine when it runs well, but I think I can say that I have had the same issue for a long time. So, not knowing whether people will still react on this topic, but I can at least give it a shot.

The symptoms:
- After a cold night, or a 3+ days of not starting the engine, the engine runs usually smooth as silk with a lot of power in all the rev range?
- The warmer the engine gets, the more rattling starts to occur, indeed disappearing when applying more than 75% throttle or doing not more than about 20% throttle.
- Car feels much less torque and consumption gets higher, higher than it should be.
- It feels like the car had a 'dead zone' in its throttlepedal range?
- When the rattling appears, you can 'solve' it by applying much more power or lift off and let it accelerate slower?

I drive a Swedish car, and this car had a 'powerbox' installed before. (I removed this) the symptoms became just less noticable but stayed exactly the same. Which gave me the indication that it has something to do with fuel..

I connect the car to MES and cant basically find anything wrong. Also is the car in a very very good state under the bonnet, I have absolutely no oil consumption. The only thing i cant seem to read out (As far as I believe, its the ECU refusing to present me this data) Its the message i get in AlfaOBD at least.. is the fuel temperature. Now I have disconnected the fueltemperature connector and I do not notice any difference in running.
Also all pressures (incl common rail pressures) are up to what they should be according to MES.

The only thing I noticed is that I have track two of my throttle pedal potentiometer often spiking down to 0v. But I refuse to believe that this has something to do with the rough running to be honest.

Often the connector from the throttle pedal potentiometer is giving issues, I have soldered through these cables. Without any noticable difference.

So the weird part is, that I sometimes do notice difference when i drive the car over a short bump in the road.

Also when I let the car idle a long time, (6-10 mins) and start driving again, the car behaves much much better for a short while. When the fuel tank is almost empty.. the rough running get worse, when I then fill up completely.. the rough running disappear for a big part again.

Do your symptoms relate to what i described here? And have you perhaps solved it already?

Now I suspect a fuel starvation issue for a longer time already. And I know from a very well known and good Dutch Italian car software specialist that told me that there are 6 different software versions for the 2.8jtd and especially 1 really sucks.

The rattling you guys describe.. i can now be sure for a 100% that it only happens when the Pilot injection is active. Thats why when you apply full throttle it stops.. cause this pilot injection is only active in certain circumstances. I think that this is a big clue, and I am trying to get an answer still if the rattling can occur when there is a fuel starvation (most likely caused by the software when fuel gets warm) that especially the pilot injection is starting to make noise.

Also as the symptoms are quite much worse with a empty fuel tank compared to with a full fuel tank.. an empty fuel tank is much more easy to make all the remaining fuel to become hot? Fresh new fuel never has this temperature and therefor it runs much better for a while again?

So.. fuel temperature being the issue? How come that I cant read out specifically this sensor from the ECU? That it keeps saying 0 degrees or with Alfaobd 'ecu refuse request' or something like that. Is the ECU of the 230Duc 2.8 not calculating in this factor with quantity and timing of the injection?

Do your symptoms relate to this?

Greetings,
Danny

Hi Danny and like you I have exactly the same problem with my 2003 , 208jtd It rattles between 2000-2500 revs only when hot. The more the load the more the rattle. Rev the engine unloaded and its fine through the revs. Either side of these parameters it runs as sweet as a nut. There are so many so called reasons for this its difficult to get to the bottom of it without spending a fortune on new and often unnecessary fixes. Probably best reason I have read is from a fleet owner who ran these for many years . Apparently for some reason when the engines were put together on some the exhaust gasket was not fitted / poorly manufactured . This lead to part of the gasket flapping against the metal . Obviously when cold its not a problem but as it heats and expands then the gap gets larger and the gasket starts to chatter. Some people on hearing this have checked the exhaust manifold to find carbon / exhaust gas markings and with a new gasket put it right. Issue is getting the manifold off in situ without breaking the studs is pretty difficult and a one way ticket. My only issue with this reason is that its pretty loud at times and not sure the above would cause this.
Can I ask if you have managed to sort yours as I live with mine as I fear hours of work with no improvement . Easy to avoid revs by using the gearbox but obviously not ideal. Thanks Howard

 

[Communicator]

Hi Danny and like you I have exactly the same problem with my 2003 , 208jtd It rattles between 2000-2500 revs only when hot. The more the load the more the rattle. Rev the engine unloaded and its fine through the revs. Either side of these parameters it runs as sweet as a nut. There are so many so called reasons for this its difficult to get to the bottom of it without spending a fortune on new and often unnecessary fixes. Probably best reason I have read is from a fleet owner who ran these for many years . Apparently for some reason when the engines were put together on some the exhaust gasket was not fitted / poorly manufactured . This lead to part of the gasket flapping against the metal . Obviously when cold its not a problem but as it heats and expands then the gap gets larger and the gasket starts to chatter. Some people on hearing this have checked the exhaust manifold to find carbon / exhaust gas markings and with a new gasket put it right. Issue is getting the manifold off in situ without breaking the studs is pretty difficult and a one way ticket. My only issue with this reason is that its pretty loud at times and not sure the above would cause this.
Can I ask if you have managed to sort yours as I live with mine as I fear hours of work with no improvement . Easy to avoid revs by using the gearbox but obviously not ideal. Thanks Howard

@gonzo1 does you vehicle have the metal canister type of fuel filter, and is it a late registered x230, or an x244 model?
I ask because the fuel temperature sensor does not appear on engine management diagrams for the x244, with metal canister fuel filter. There is a thermostatically controlled fuel heater in canister type filter, but a separate sensor is not shown on the diagrams. This could be an error of omission from the diagram, of which I have already located others in eLearn for the x244. I have not experienced any knocking from my 2006 x244 2.8jtd, which has the plastic bodied all black, so called "green filter" which contains a fuel temperature sensor.

 

[gonzo1]

Hi there and thanks for response. My motorhome has the metal fuel filter and I'm sure its an x 244. Vehicle was registered in Dec 2003 but as its an A class the chassis is probably early / mid 2003. It has the new gearbox on it - not the old Citroen one with the 5th gear bolted on the the gearbox.
I'm not at all sure if it has a fuel temp sensor but I have thought of changing the pressure sensor on the common rail as its an easy swap and relatively cheap. Issue is even when it pinks / rattles between 2000 - 2500 rpm its not running rough and always starts on the button. If it did have a fuel temp sensor any ideas on where it is located.?? Thanks Howard

 

[Communicator]

Hi there and thanks for response. My motorhome has the metal fuel filter and I'm sure its an x 244. Vehicle was registered in Dec 2003 but as its an A class the chassis is probably early / mid 2003. It has the new gearbox on it - not the old Citroen one with the 5th gear bolted on the the gearbox.
I'm not at all sure if it has a fuel temp sensor but I have thought of changing the pressure sensor on the common rail as its an easy swap and relatively cheap. Issue is even when it pinks / rattles between 2000 - 2500 rpm its not running rough and always starts on the button. If it did have a fuel temp sensor any ideas on where it is located.?? Thanks Howard

Firstly model identification, which is indicated by the VIN, starting either ZFA230......, or ZFA244......... Alternatively on the x244, reverse gear selection is next to first on the MLGU box, which still has fifth gear in a separate compartment with drip feed lubrication. Advice that I try to follow is not to use in first mile, if vehicle has been standing for more than overnight.

The fuel sensor has a reference in x244 eLearn as K081, but I cannot this on wiring/location diagrams, it only appears in the connector pinout detals.
I have attached an extract from x244 eLearn, which confirms the presrence of the sensor in the filter mounting, so yet another instance of items missing from eLearn diagrams.

 

[gonzo1]

Thanks mine has sensor in filter as nothing between this and the fuel rail. Can these be renewed. Im fine with gearbox its the rattle/pinking noise between 2000-2500rpm im trying to cure.appreciate your help

 

[gonzo1]

Just to say your diagram and info was really helpful Howard

 

[gonzo1]

Hi there and thanks. Its definitely a 244. Filter does indeed have the temp sensor in the head. I understand from the attachment it only heats fuel below 6 degrees. Given my rattle occurs in summer i assume this rules out fuel temp. Do you think its worth changing pressure sensor on fuel rail.? Must say apart from the flapping gasket theory I'm a bit lost. However up mountain roads under load its very noisy which seems to rule out flapping metal gasket but who knows. Good tip on gearbox and i always add an extra 250 ml when filling box. Thanks Howard

 

[Communicator]

I feel that I cannot offer advice as to whether or not changing

Thanks mine has sensor in filter as nothing between this and the fuel rail. Can these be renewed. Im fine with gearbox its the rattle/pinking noise between 2000-2500rpm im trying to cure.appreciate your help

In my understanding the term "fuel rail" is normally a reference to the high pressure (hp) fuel manifold, which runs alongside the cylinder head on common rail engines. The fuel filter is part of the low pressure (lp) fuel system, and the hp pump is between the filter and the fuel rail.

 

[Communicator]

Hi there and thanks. Its definitely a 244. Filter does indeed have the temp sensor in the head. I understand from the attachment it only heats fuel below 6 degrees. Given my rattle occurs in summer i assume this rules out fuel temp. Do you think its worth changing pressure sensor on fuel rail.? Must say apart from the flapping gasket theory I'm a bit lost. However up mountain roads under load its very noisy which seems to rule out flapping metal gasket but who knows. Good tip on gearbox and i always add an extra 250 ml when filling box. Thanks Howard

I do not feel able to advise on the possible effect of changing the hp rail sensor, as I have not experieced this "knocking" problem. However a change of sensor could eliminate one possibility. I have heard diesel knock on a different engine many years ago. It can sound very metallic, to the extent that on that vehicle, a loose tappet had been considered as a cause. Modern engines are more refined, and less subject to diesel knock, which is a possible cause of your "rattle".

If I understand correctly, you problems occur when the enine is hot, and working at high power. In this condition on the 2.8jtd, fuel rail pressure and injection duration are both probably increased. I am wondering whether some of the increase in injection duration, is obtained by advancing the start of injection?

Looking at the attached description extracted fom eLearn, engine temperature affects injection timing.

 

[gonzo1]

Thanks again. Just to clarify knocking/rattling is inly between 2000 -2500 rpm . Worse under load and only when engine hot. Howard