Poor mileage Nj Pajero

[Bluepajee]

Hello, so I bought a 2.8t 94 Pajero with 337k on the clock, one owner, said he towed a heavy trailer for about 40% of its life, was well looked after, regular basic service etc.

Injectors recond about 100,000 ks ago.

It's well under power, struggles to get to 100km/hr and any hill means back to 4th and probably 80km/hr, if its steep sometimes 2nd/3rd.


Getting about 18l-20/100km on highway (loaded)

Car starts fine every time, but seems like it's miss firing for the first 30seconds.

I just did oil and fuel filter change as well as new oil as well as air filter.

Car does blow whitish smoke under load, usually when turbo kicks in.

Also when crusing and down gearing for a town at 60 K/hr if it's in 4th it feels like the low revs make it miss again, kind of lurchy.

Plans at this point are to do a compression test and while I'm at it renew injectors and glow plugs.

Do a MAF clean, maybe oxygen sensor clean/replace (can you clean them?)

Wondering if there's any advice here on what's potentially my problem?

It's not using oil, but also my oil pressure guage ain't working!

Have just got a EGT guage and turbo pressure guage that needs to be installed too.

But at this stage, just to be able to accelerate to 100km/hr is essential, and fuel mileage next.

So please shoot me in the right direction, bought this car to learn more about diesels and to have a car I can work on myself so I'm enjoying the process but some helpful tips would be greatly appreciated.

Thanks T









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[nj swb]

Hello, so I bought a 2.8t 94 Pajero with 337k on the clock, one owner, said he towed a heavy trailer for about 40% of its life, was well looked after, regular basic service etc.

Injectors recond about 100,000 ks ago.

It's well under power, struggles to get to 100km/hr and any hill means back to 4th and probably 80km/hr, if its steep sometimes 2nd/3rd.


Getting about 18l-20/100km on highway (loaded)

Car starts fine every time, but seems like it's miss firing for the first 30seconds.

I just did oil and fuel filter change as well as new oil as well as air filter.

Car does blow whitish smoke under load, usually when turbo kicks in.

Also when crusing and down gearing for a town at 60 K/hr if it's in 4th it feels like the low revs make it miss again, kind of lurchy.

Plans at this point are to do a compression test and while I'm at it renew injectors and glow plugs.

Do a MAF clean, maybe oxygen sensor clean/replace (can you clean them?)

Wondering if there's any advice here on what's potentially my problem?

It's not using oil, but also my oil pressure guage ain't working!

Have just got a EGT guage and turbo pressure guage that needs to be installed too.

But at this stage, just to be able to accelerate to 100km/hr is essential, and fuel mileage next.

So please shoot me in the right direction, bought this car to learn more about diesels and to have a car I can work on myself so I'm enjoying the process but some helpful tips would be greatly appreciated.

Thanks T

I'll guess you have a significant over-fuelling problem, but I'm not sure where to start.

Rough idle could suggest injector spray problem, but if that was the problem I would expect black smoke under load (incomplete combustion) and not white smoke.

Over-fuelling under load could be related to how the injector pump responds to boost i.e. the pump thinks boost is much higher than it really is. NFI what could cause that.

White smoke can also be steam from coolant entering the combustion chamber, but if that was happening I would expect you'd have more evidence of problems. Does it use coolant?

I think your idea for boost gauge is a great place to start, and new injectors could be a relatively simple way to rule them out - and little excessive if they're not the problem, but that's a call for you to make.

[Bluepajee]

Thanks for your reply, doesn't go through coolant and there's no bubbles on the reserve when I pull the cap off - while the car is running .

Yeah it's a funny old suite of problems and hopefully there's a magic bullet thatll solve em all haha

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[Travel Tragic]

Poor mileage

Hi, as a past owner of a 98 mod 2.8 diesel that I sold at around 400,000 kms maybe I can help. To my knowledge the 2.8 litre is an old fashioned diesel that does not have a computer so probably no Maf or oxygen sensor. The average time between injector rebuilds was around 100,000 kms so that's something to look at plus the injector pump is maybe near it's use by date. John

[Nab]

Have you checked the simple things? Air filter, fuel filter etc can sometimes cause funny issues.

[Bluepajee]

Yup, I changed the air, fuel and oil filter pretty much straight away...


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[Bluepajee]

One area that I might check even before injectors will be the EGR - INLET area and see how funked up it is, seems like possibly 337klicks of no EGR block could have well and truly impaired the intake... Fingers crossed a clean of intake manifold will be a big help

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[Bluepajee]

Bummer, had a second to have a look under the hood and the EGR valve has already been completely removed ):

There is a tonne of soot though between the inlet manifold and the head maybe that's a clue?....

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[pharb]

4m40 is proper old school.
No EGR, no MAF, no oxygen sensor.

Just mechanical pump, throttle cable, electric wire to fuel shut off and pnuematically controlled turbo waste gate.

Mine has 460,000km on it now. Still gets better than 14L/100km even though only used to cart trailer loads of wood home for the winter. I can't recall ever getting worse than that even when loaded above GCM with camping trailer etc.

Glow plugs only function at start up, and a few seconds afterwards. Will make it hard to start in cold weather, and miss and fart for a few minutes until combustion chambers have warmed a bit. Would explain a miss at start up, but won't affect running or economy. Relatively simple exercise to replace glow plugs, with a few little items to be aware of as you do undertake the task.

Black smoke is caused by overfueling, or to much fuel for the amount of oxygen available. Fuel carbonises due to incomplete combustion.

White smoke is generally caused by the fuel vaporising before combusting due to insufficient heat. This could be caused by lack of compression, or injection timing not quite right.

Very simplistic explanations.

From memory the injection pump is attached to the timing case with 2 or three nuts on studs, the studs passing through slotted holes on the pump.

I simple experiment could be to loosen those nutes and rotate the pump slightly. I can't recall which direction would advance or retard timing. Mark the pump and timing case so you can return it to the priginal position if needed.

If it does make a difference possibley worth investigating getting the pump proffessional timed, or even refurbished.

Another simple thing to check is the fuel enrichment mechanism on the top of the pump. This will have a small rubber hose running to it from the inlet manifold somewhere. This could be blocked or restricted, preventing the fuel enrichment device working properly as the turbo comes on boost.

For reference my NJ had the injectors recoed at about 300,000km, but has never had the pump off either since I have had it (since about 200,000km), or to my knowledge prior to my ownership.

[Bluepajee]

Thanks for your detailed response!!

I'll try your potential remedies out but found this vid

https://youtu.be/BYp83vxUnvY

Very similar issues to what I'm experiencing, just not as severe, so I'm going to bite the relatively cheap bullet and order some inlet gaskets, pull the inlet manifold off and Inspect (hopefully I'll find a severely marginalised intake) and give it a solid clean and reinstall with new gaskets and potentially all my problems will be solved!!

The issue in the video around 2k revs is the miss firing / coughing I was trying to explain, just jumped in the car and revd it in neutral and sure enough, at 2k revs or there abouts it coughs and stutters, that's what I was also experiencing when down gearing.

Anyway, for those playing at home I'll keep updating in the chance in future people will find this thread somewhat illuminating, and until then please feel free to keep chiming in!

Cheers T

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[Bluepajee]

And PS, thanks for the MAF / OXYGEN sensor tip, that just saved me a helluva lot of searching the internet to see if indeed I did have them and where! I didn't originally think I had such sensors but I was advised to check them by an old 4d56 owner.

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[Bluepajee]

Okay update for anyone interested.

Exhaust manifold big crack and glow plugs not getting power - explains the smoke on start up and yeah low power because the turbo ain't getting much to work with.

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[Martynhpajero]

I'd get that boost gauge fitted and see if your getting about 9psi. When I bought mine it was a bit gutless. Fitted gauge and was only at 7 psi. A couple of washers behind the waste gate actuator took it up to ten. Much better power.

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[Bluepajee]

Thanks mate I've got the sensor for EGT and boost ready to install so I'll do it all at the same time

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