General 2.0 JTD Fuel Consumption

[Lotus26R]

I know that fuel consumption falls into the "how long is a piece of string?" category but I'd like to understand what sort of fuel consumption owners are getting from their 2.0 JTD Motohomes. Mine is a 2004 SWB 2.0 Ducato fitted with an over-cab, coach built body (Knaus Sport Tourer 500).

Running on empty motorways at between 50-60 mph, I'm unable to better 27mpg. On mixed roads recently I dropped to 24mpg. Overall, the running feels fine - super sweet actually. I do have a very black exhaust however and, particularly on start-up, the exhaust is most unpleasant.

At the risk of drifting into technical, I suspect I may have some problems with my emission control (EGR/Throttle Valve) system - just not sure quite how they may harm fuel consumption - if at all. Anyone with experience one way or another please?

Does anyone have a recommended diesel expert in/around the Harrogate area - someone who will diagnose the problem rather that "changing everything" to fix the problem?

Appreciated.

 

[varesecrazy]

Hi
The obvious initial question..

Does the thermostat work effectively..?

Something sounds like its causing overfuelling... but a fair few variables

5 speed box.. tyres at correct pressures
No brake drag..?


Is this a recent problem..or a recent purchase??

 

[Lotus26R]

Hi. The van is a new purchase and the EML had been disabled (LED taped over) and the right hand (throttle valve) actuator had been disabled (unplugged).

TV actuator has now been re-connected, plumbed in the correct way round, MAF sensor replaced, codes cleared and not reappeared. Air filter looks OK but will be replaced today. TV seems to operate OK and plugging/unplugging EGR "makes a difference" so not completely broken, if at all.

Temperature comes up and behaves normally, van rolls well and TP's are correct at 5bar. It does have the 5 speed box.

Drive on low throttle cruise seems OK - maybe just a trace of a misfire at certain throttle settings? She's not a rocket ship but not a disaster either.

Over-fueling does seem a potential problem - the exhaust is very smelly although not black under normal operation. No odd noises, no starting issues. I'm new to diesel self help though - a lot still to learn.

 

[LandyAndy]

Have you physically seen your EGR operate? Or done a check to prove it is working and also sealing shut?

 

[Lotus26R]

No. My next plan was to remove it and do a physical - avoided so far because of the odd pipe clips it uses. It certainly "does something" and it does hold a vacuum though. Is there a tool to remove the factory clips or is it a cut and replace job?

 

[LandyAndy]

I don’t know your engine.

But

What I do know is my “system“on my X250 thought it was working fine, and no warning lights. But in actual fact the EGR was stuck 100% open. This caused very few running problems apart from smoky, bit low on power (big hills) and smelly.
The EGR held a vacuum , the vac solenoid did its thing, and throttle body did its too. But in truth the system wasn’t working as it should, and unplugging the EGR electrical system made it operate slightly better, as it then stopped using the throttle body. But not a complete cure as it is still allowing exhaust gases through permanently, although now less. So the two opticians I had was to get the EGR to work fully or to remove the EGR (via blank plate), but also electronicly to stop the throttle body operating during EGR cycles.

I know this info will be different to yours as different engine, but the basics of the system will be same, and was all a steep learning curve for me. I know about engines, and all that stuff, but little about supposedly planet saving BS.

Any questions ask, or ignore if irrelevant

Andy.

 

[Lotus26R]

Good pointers - thanks. I'll tackle the EGR next then - although the two retaining bolts look like they'll be even more fun to remove than the factory pipe clips.

 

[LandyAndy]

I could not, and can not get my EGR valve out. It’s is REALLY stuck. So in the end I unbolted the end of the cooler from the engine intake side, as less rusted due to less heat. Then found a flex pipe that I fattened with ins tape, shoved this up the EGR cooler outlet, and could blow through this (so into the exhaust manifold) with ease regardless of what the EGR valve position. This showed my EGR condition.

Sorry. Crap at typing and explaining. More a hands on type person.

 

[Lotus26R]

Thanks again - I'll let you know what happens next....

 

[Anthony489]

Hi Lotus26R

As your van is 2004 I'm assuming its Euro 3 and will have an exhaust catalyst plus an early EGR system. The EGR is supposed to reduce Nitrogen oxides in the exhaust, it won't have much effect on smoke emission if working properly.

Your fuel usage on the level will be dominated by wind resistance, and a square-ish shape with an overcab is always going to have more drag than an ordinary van shape with rounded corners. Maybe the same drag at 60 mph that an ordinary van has at 70 mph ? I agree that 27 mpg is a bit disappointing, but my gut feeling is that you will be doing well to better 30 mpg.

If you are hill climbing or accelerating between roundabouts on non-motorway routes, the weight is going to have more of an influence.

Smelly/sooty exhaust immediately after startup isn't unusual, as the cylinder walls will be cold and the catalyst won't be hot enough to work. I can't remember what arrangements these engines have for very cold starting, but if it has glow plugs and they aren't all working that can also give this effect for a minute or so until things warm up. Sooty exhaust pipe means that some of the time it has too much fuel for the available fresh air coming in. However, unless you have black smoke pouring out the whole time, any diesel being injected should be producing useful power.

By all means get the EGR system working as it should, but I don't think it's going to make a huge difference to MPG unless the EGR valve is stuck open. LandyAndys suggestion of blowing back through it sounds like a good test without much dismantling. At rest with no vacuum the valve should be fully closed. It does sound as though there has been some trouble in this area which the previous owner has bodged.

To the best of my knowledge, the ECU cannot directly tell the position of the EGR valve or the Throttle Body flap. However, it does seem to be able to check the operation of the EGR system by using inputs from other sensors (MAP, MAF, RPM etc) and will throw a code/warning light if things are deemed to be faulty.

 

[Communicator]

No. My next plan was to remove it and do a physical - avoided so far because of the odd pipe clips it uses. It certainly "does something" and it does hold a vacuum though. Is there a tool to remove the factory clips or is it a cut and replace job?

The stainless "Ezyclik" type of clips which are made for specific pipe sizes, and used on air inlet hoses can be removed, and replaced with special pliers, of which "Laser 4231" are an example. Other clips probably need to replacing.

 

[Lotus26R]

Hi Lotus26R

As your van is 2004 I'm assuming its Euro 3 and will have an exhaust catalyst plus an early EGR system. The EGR is supposed to reduce Nitrogen oxides in the exhaust, it won't have much effect on smoke emission if working properly.

Your fuel usage on the level will be dominated by wind resistance, and a square-ish shape with an overcab is always going to have more drag than an ordinary van shape with rounded corners. Maybe the same drag at 60 mph that an ordinary van has at 70 mph ? I agree that 27 mpg is a bit disappointing, but my gut feeling is that you will be doing well to better 30 mpg.

If you are hill climbing or accelerating between roundabouts on non-motorway routes, the weight is going to have more of an influence.

Smelly/sooty exhaust immediately after startup isn't unusual, as the cylinder walls will be cold and the catalyst won't be hot enough to work. I can't remember what arrangements these engines have for very cold starting, but if it has glow plugs and they aren't all working that can also give this effect for a minute or so until things warm up. Sooty exhaust pipe means that some of the time it has too much fuel for the available fresh air coming in. However, unless you have black smoke pouring out the whole time, any diesel being injected should be producing useful power.

By all means get the EGR system working as it should, but I don't think it's going to make a huge difference to MPG unless the EGR valve is stuck open. LandyAndys suggestion of blowing back through it sounds like a good test without much dismantling. At rest with no vacuum the valve should be fully closed. It does sound as though there has been some trouble in this area which the previous owner has bodged.

To the best of my knowledge, the ECU cannot directly tell the position of the EGR valve or the Throttle Body flap. However, it does seem to be able to check the operation of the EGR system by using inputs from other sensors (MAP, MAF, RPM etc) and will throw a code/warning light if things are deemed to be faulty.

Thanks Anthony. All makes a lot of sense. I do understand the drag element so tend to cruise nearer 50 than 60 at the moment. Similarly, I'm as gentle on the gas as respect for the folk behind allows - I can normally wring the last foot out of a gallon of fuel so the 27, and one time 24 is a bit saddening. I've just fitted a new air filter and driven 20 miles with the vacuum connection on the EGR disconnected and stoppered. All seemed to drive well enough although the system did throw up an EGR warning code - how it knows that I'm not sure. I'm going to poke a bore camera into the inlet manifold where the EGR inputs to see if that sheds any light. Thanks again.

 

[Lotus26R]

The stainless "Ezyclik" type of clips which are made for specific pipe sizes, and used on air inlet hoses can be removed, and replaced with special pliers, of which "Laser 4231" are an example. Other clips probably need to replacing.

Thanks Communicator - I have a pair of clic-r pliers en-route from Amazon so will postpone the dismantling until tomorrow. I'll replace with the screw version.

 

[Lotus26R]

Looking again at the eLearn description of my system it shows the right hand solenoid as connecting directly to the turbo waste gate - but it doesn't, it connects to the throttle valve. The waste gate actuator is fed by a short pipe that seems to start in the turbo itself and work by pressure, not vacuum. I've failed miserably to find a workshop manual - is there any other source of info available please?

 

[Angelosw9]

I know that fuel consumption falls into the "how long is a piece of string?" category but I'd like to understand what sort of fuel consumption owners are getting from their 2.0 JTD Motohomes. Mine is a 2004 SWB 2.0 Ducato fitted with an over-cab, coach built body (Knaus Sport Tourer 500).

Running on empty motorways at between 50-60 mph, I'm unable to better 27mpg. On mixed roads recently I dropped to 24mpg. Overall, the running feels fine - super sweet actually. I do have a very black exhaust however and, particularly on start-up, the exhaust is most unpleasant.

At the risk of drifting into technical, I suspect I may have some problems with my emission control (EGR/Throttle Valve) system - just not sure quite how they may harm fuel consumption - if at all. Anyone with experience one way or another please?

Does anyone have a recommended diesel expert in/around the Harrogate area - someone who will diagnose the problem rather that "changing everything" to fix the problem?

Appreciated.

I've a similiar motorhome with the same engine for the last 5 years, mine does around 9km/l which is 25.5mpg... the black smoke could be carbon build up, try bringing the engine to running temperature then pull first or second gear up to the rev limiter maximum for a hundred yards at a time, repeat a few times until it will stop smoking completely... diesel engines have a tendency to build up carbon deposits, more so if you drive in traffic / short distances / with a cold engine, i do this routine everytime just before having the MOT and when i notice too much smoke coming out of the exaust... this motor is a bit under powered for motorhomes but so far can't complain as it has been very reliable

 

[Lotus26R]

Thanks Angelo. I’ve now disconnected the whole EGR/TV system and the van runs much more sweetly. Last tank returned 28mpg and the exhaust is notably less black. I’ve also put two bottles of fuel system cleaner through but not done the Italian Service you suggest yet - my ears always tell me to change gear to preserve my mechanical sensibilities. I’m away in it today so may be a good time to forget those tomorrow. Thanks for your thoughts.

 

[Angelosw9]

Thanks Angelo. I’ve now disconnected the whole EGR/TV system and the van runs much more sweetly. Last tank returned 28mpg and the exhaust is notably less black. I’ve also put two bottles of fuel system cleaner through but not done the Italian Service you suggest yet - my ears always tell me to change gear to preserve my mechanical sensibilities. I’m away in it today so may be a good time to forget those tomorrow. Thanks for your thoughts.

Ahah, the Italian Service was actually an Irish one... used to have a Citroen Xantia with a mechanical diesel pump, first MOT after driving in London it pushed out a massive cloud of black smoke... the Irish mechanic told me to go around the block in first gear and try again... he said it's carbon deposits in the turbo and they blow away with a good spin... forgot to say, make sure your timing belt is fine before you do that

 

[Angelosw9]

One thing that happened with my motorhome, after driving back from Tenerife the front right indicator and full beam had stopped working, the corrugated conduit with the cables inside that connects to the headlight had come lose from the plastic retaining clip on the chassis, found it leaning against the alternator belt that had cut a few of the cables and there was just ~1/3 width of the flat belt left, only realised it once i got home, i was lucky to make it back with that tiny strip of belt and normal beam still working... not sure if the cable arrangement is the same in yours as mine is a LHD, if it's all it needs is a cable tie to keep it in place... at first i thought it was a fuse blown which brought another problem up, there's a fuse box with near the front grill, the cover has 2 nuts/bolts, mine were well rusted, managed to undo one after a day soak in WD40 but had to cut the other one off which ages, the good thing is that i found out at home and not while stuck on the side of the road... it might be worth checking if they unscrew and put some grease on the thread if they do, i keep the cover on with 2 cable ties to be on the safe side.

 

[Lotus26R]

One thing that happened with my motorhome, after driving back from Tenerife the front right indicator and full beam had stopped working, the corrugated conduit with the cables inside that connects to the headlight had come lose from the plastic retaining clip on the chassis, found it leaning against the alternator belt that had cut a few of the cables and there was just ~1/3 width of the flat belt left, only realised it once i got home, i was lucky to make it back with that tiny strip of belt and normal beam still working... not sure if the cable arrangement is the same in yours as mine is a LHD, if it's all it needs is a cable tie to keep it in place... at first i thought it was a fuse blown which brought another problem up, there's a fuse box with near the front grill, the cover has 2 nuts/bolts, mine were well rusted, managed to undo one after a day soak in WD40 but had to cut the other one off which ages, the good thing is that i found out at home and not while stuck on the side of the road... it might be worth checking if they unscrew and put some grease on the thread if they do, i keep the cover on with 2 cable ties to be on the safe side.

Thanks Angelo - I'll check. My n/s front strut started making very odd sounds on the way back from Kendal today - if it's not one thing....

 

[Angelosw9]

My car failed had its first MOT last month, worn rubber bush on the front shock... nothing major if it wasn't that had worn the tyre and the pair cost more then the bush fix... still can't complain, first repair in 14 yrs