Bad fuel economy - reasons?

Hi guys. Any advice will be appreciated.

I've recently purchased a 2009 MY08 ST Patrol with 120k on the odometer.

I've done a test on fuel efficiency for town driving only and got 16.6L/100 (17MPG)

I was expecting to get around 13L/100 so makes me believe there could be an issue somewhere.

The vehicle is stock standard with no accessories using standard size road tyres. I gave it an oil change as soon as I got it home and replaced oil and air filters.

I have driving it around trying to save on fuel, so no heavy foot and still got the poor results.

I have been driving around with the O/D on which was stated in the manual. Not sure if this would help town driving if it were switched off.

I have used a fuel conditioner on each fill up.

After a highway trip it returned nearly 14L/100.

Is there anything I could do/ or check to help improve efficiency? Could the EGR valve not be functioning properly and affecting economy?

Kind regards,


Aaron.

Attachment 69200
This is an image of oil around turbo. Could this be the issue?

Clean the MAF sensor and disconnect the Battery for 30 minutes to force the ECU to 'relearn' the settings and see how that goes.

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Originally Posted by the evil twin

Clean the MAF sensor and disconnect the Battery for 30 minutes to force the ECU to 'relearn' the settings and see how that goes.

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Thanks. Just bought some MAF sensor cleaner. Will give it a go and clean out intercooler an see how that goes.

a catch can should keep your IC cleaner but if its oily to look at,,chances are its leaking.
Nothing you can do about it except buy a fully tigged replacement

Being a CRD, drive it like you stole it...lol These motors love revs and perform best in high RPM range. I hit 4000RPM every gear change
With that oil leak, just clean it and tighten the clamp...should sort that out

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Originally Posted by threedogs

a catch can should keep your IC cleaner but if its oily to look at,,chances are its leaking.
Nothing you can do about it except buy a fully tigged replacement

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I'm not sure yet if the intercooler is oily. I have yet to remove it and inspect. I will order the plate and scangauge II so will probably do it then. For now I'll try cleaning MAF sensor as suggested.

Anyone have an easy to follow guide on doing that?

You need the appropriate Torx bit to fit the sensor retaining screws.
Pull the sensor out and spray the ports liberally with cleaner
Allow to dry and refit

Your cooler will be oily inside. What Threedogs is saying is that stock coolers leak around the pressed ends.
You sometimes can see oil patches on the fins when they are a bit dusty.

Give the maf a clean as above.
But autos will always use more fuel than a manual.
I get 13-14L/100k on the highway so if your getting 16 around town I'd say that's a good average..

Its straight forward as ET says dont over think it
just spray over a white tissue or cloth.
Not sure on the size of the torx tool required
its either a number 2 or a 20,,,,anyone,,,
Make sure its dry before installing it again

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Originally Posted by threedogs

Its straight forward as ET says dont over think it
just spray over a white tissue or cloth.
Not sure on the size of the torx tool required
its either a number 2 or a 20,,,,anyone,,,
Make sure its dry before installing it again

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Thanks threedogs. Yeah I think i read somewhere it was a T20.

With cleaning the intercooler. Is it ok to use degreaser then flush with water?

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Originally Posted by azzacalabaza

Thanks threedogs. Yeah I think i read somewhere it was a T20.

With cleaning the intercooler. Is it ok to use degreaser then flush with water?

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Yes but make sure you dry it properly with say a hair dryer,
Tape up both ends and use a footy bit on a hand pump to create
some pressure. nothing you can do its just to comfirm its leaking.
Also as suggested clean the oily section and tighten, check the
oil level too they dont like them overfilled

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Originally Posted by Nisshead

Being a CRD, drive it like you stole it...lol These motors love revs and perform best in high RPM range. I hit 4000RPM every gear change
With that oil leak, just clean it and tighten the clamp...should sort that out

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I'm with Nisshead here, mine is an auto and I drove it like I was scared to break something. Was sitting on the 13L/100 + on highway.
Now I let it stretch its legs and regularly get mid 11L/100, that includes hills and sitting on the limit. I don't use OD as soon as I hit an incline.
Try it and see if it makes a difference.

Well. I cleaned the MAF sensor and refilled the tank. Will see what difference that makes then post the results.

Well it seems cleaning the MAF sensor did nothing. I'm still getting over 16L/100 and half of that was highway driving. :(

Could there be an issue with injectors ?

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Originally Posted by azzacalabaza

Well it seems cleaning the MAF sensor did nothing. I'm still getting over 16L/100 and half of that was highway driving. :(

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i live in the country.90% of my km are at 110....unless it a hill or a 90 degree corner....we always get around 15.5 to 16 nearly every tank....it sucks but thats is what i am use to after 2 and a half years

Yeah. I've been reading heaps on different forums. Looks like there were some that are just good on fuel and others that just suck (the ones we got). Some have bought brand new and get 15-16L/100km and others get 10-11L/100km with the same vehicle specs. I wonder if replacing the MAF altogether might help. Will also block of EGR as that may be malfunctioning causing higher fuel consumption.

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Originally Posted by azzacalabaza

Yeah. I've been reading heaps on different forums. Looks like there were some that are just good on fuel and others that just suck (the ones we got). Some have bought brand new and get 15-16L/100km and others get 10-11L/100km with the same vehicle specs. I wonder if replacing the MAF altogether might help. Will also block of EGR as that may be malfunctioning causing higher fuel consumption.

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To be honest. If someone says they are getting 10-11 ltrs in a 3T hunk of metal powered by a tiny 4cylinder 3ltr diesel, i really dont think they have done their calculations right.

Sent from my SM-P600 using Tapatalk

FWIW, Mrs MB's old GU 02 3.0L manual immaculate wagon (stock rocket) with zero fruit bolted on and not towing could get 12.0L if we tried hard enough on the flat highway. Never really got it over 16.0L, it was a great thing I reckon, more than fit for its purpose at our time in life !

I just noticed when my wife started the Patrol to leave for work this morning, a puff of white smoke came out the exhaust. I'm no mechanic, but should I be worried about this?

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Originally Posted by MB

FWIW, Mrs MB's old GU 02 3.0L manual immaculate wagon (stock rocket) with zero fruit bolted on and not towing could get 12.0L if we tried hard enough on the flat highway. Never really got it over 16.0L, it was a great thing I reckon, more than fit for its purpose at our time in life !

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Haha I was going to edit my post but fell asleep. With the optimal conditions and an empty Patrol with nothing bolted on you may get 12-13Ltrs. Everything counts I suppose thats bolts onto your car. I know when I take my roof rack off I could shave off maybe half a litre just in wind drag.

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Originally Posted by azzacalabaza

I just noticed when my wife started the Patrol to leave for work this morning, a puff of white smoke came out the exhaust. I'm no mechanic, but should I be worried about this?

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Might be just some unburnt fuel on its first start. Depending if the morning is real cold or not too. My Patrol on real chilly mornings will do the same. Might be oil but something of that age I wouldn't think so. Just keep an eye on the oil levels...

Thanks mudski. I live up on the Fraser Coast QLD, so it's not cold at all really. I've read this could indicate a problem with glow plugs, injector timing or cracked head gasket. I might need to book it in to a local diesel mechanic to have a look at.

I forgot to mention can be caused by air getting into fuel line. I'm not sure when fuel filter was last changed on it, so i probably should get that done.

If there was air in the line I would have thought it would splutter and carry on until the air is out... Just go over the hose clamps and tighten them up.

I'm thinking I should probably get my injectors inspected/cleaned. Any idea how much this usually costs?

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Originally Posted by mudski

To be honest. If someone says they are getting 10-11 ltrs in a 3T hunk of metal powered by a tiny 4cylinder 3ltr diesel, i really dont think they have done their calculations right.

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I have to disagree, my GU2 would do over 1100 km between fills, but only in autumn & spring, once the AC was on & the boat trailer connected it went south.
Graham

Our 2006 3.0 Di is usually around 12 -13 /100 but can gut up to 14-15 if I push it. Plenty of extra weight-steel bull bar, winch, drawers with recovery gear and tool etc etc. Only time I hit over 15 across the Simpson- then it was 24!!!.
Not nursed but not flogged either.
Just did a refuel--667 km and 81.12 litres==12.16 l/100. That gives me a range of 988 km, at least theoretically. About half of this was from Chinchilla, the balance around the Gold Coast. This seems to be about standard for me.

Those are nice figures @Dr Gary. Since I have no attachments to my trol apart from tow bar and still get much higher than that, i feel envious. 12.16 I would be really happy with.

Just an update on my fuel economy. I've since done the EGR block hoping to improve things for me. Unfortunately, my fuel figures have worsened from 16.6L/100 to now 17.4L/100 (town driving).