D40 White Smoke and Rough Idle

[slcrugby]

Hey guys first post as I haven't had anything to contribute until now as after extensive forum searches I found that all my questions had been answered.

A bit of background I bought the 2007 Navara St-X 126kW Manual Diesel about 4 months ago from the Father in Law who had it since new. Regularly serviced and maintained (He is probably the only family member I would buy a second hand car off as I know he takes good care of his gear). Anyway we drove it from Perth to Brisbane around New years and lost the cruise control on the first day which made the 5500k seem about twice as far. Once we got home replaced the neutral position switch based on feedback from the forum with a unit from Gary at Nizzbits and she has been like new ever since.

Anyway to the topic over the past 2 months I have been trouble shooting my way through the possible engine issues which as the topic suggests are White smoke and rough idle. As I haven't had the car since new I am not too sure exactly what she is meant to sound like however I started up a mates 2008 140kw YD25 and the sounds were like chalk and cheese however I am not sure if that was due to the engine upgrade.

I have noticed that the white smoke is only there on a cold start and not once I have driven it for around 10-15+ mins to the shops and quickly popped in and started her back up again and sounds like it runs smoother once the engine was warm. However if I leave it at work all day and return the white smoke and rough idle would return.

I placed an EGR Mod at the beginning of Feb 2014 but there wasn't any white smoke that I knew of at this stage. The smoke started roughly a month later so beginning/middle or March 2014. No catch can though and you can bet your bottom dollar there is oil between the turbo and the intercooler (I checked the other day). I am however planning to do this in the coming few weeks with a provent as the SCA special I have would require too much of a step down in inlet/outlet pipe diameter for my liking.

About 6 weeks a go I put in a snorkel and sealed her all up and at this time I also replaced the air filter. The air filter element is still clean. So it was smoking before I put in the snorkel and the filter. However it didn't improve afterwards and steadily worsened over the following weeks.

I run an OBD2 with the Torque Pro App as many do on here and there are no error codes on the ECU.

I then changed the oil and filter about 1500k ago to make sure there wasn't any issues in the oil and it was due anyway.

Next step was start the engine with the fuel cap loose and no changes then so I assume from what I have read that this should rules out the SCV.

I also then cleaned the MAF with contact cleaner as per the directions on here without any improvement.

The next day I ran the Moly Purge Plus through the injectors. Now I had a little bit of black smoke with acceleration before this which appears to be all gone post the purge. However the white smoke remained but it is the first purge I am aware of being done on this engine. I assume the cleaning had occurred due to the absence of black smoke.

500k ago I changed the fuel filter wondering if it had caused any issues with some dirty fuel on the way back across the Nullabor or another regional centre. Due to the delay in the white smoke and the return from the trip about 2 months earlier I didn't see a strong link but thought it was going to be cheaper than the following investigations so proceeded anyway. It was previously a genuine filter and I used a Ryco I know that there is a lot of talk around non genuine fuel filter causing problems however there was no change in performance or smoke after the change. I will continue to monitor and change to the genuine one I have since ordered and is ready to go.

I then pulled out the D40 service manual I managed to find on Google somewhere which suggested as I had thought that the glow plugs could be the cause. Makes sense really white smoke can equal unburnt diesel and faulty glow plugs could be a cause. However once again I got the glow plugs Wednesday last week and did the swap. No I didn't test the glow plugs to see if they worked or not (I wasn't sure how to be honest). So I pulled them out and they came out easy enough with only a little carbon build up on the end of the plugs. In the new ones go. The white smoke and rough idle remains however I would say the white smoke has reduced significantly say by ~50% now.

Now I return to my dreaded and initial suspicion of injectors. So after some more Google work I find a YouTube clip of a guy running a YD25 on a picoscope for a relative compression test (I assume) which further adds to the case that it is injectors. When he knocks out 3 of the injectors (one at a time) you can hear the engine start surging and carrying on but when he knocks out the 4th injector it makes no difference. So I checked the injector connections and it appears as though they were all connected and functioning.

Is the engine down on power? I have no idea. Does the engine sound any different to when I bought it? No I don't think so and being my first diesel other than a brand new i30 12 months earlier I thought this was what a bigger diesel was meant to sound like. About a month before we picked it up I hit up the Father in Law about the likes of timing chains and injectors and asked him:
- was he aware of any issues with them?
- Had they ever been replaced?

The answers were both No so he took it to the mechanic the next day who said that he never heard of those issues on the YD25 but said most of the issues he had seen were on the ZD30. No further investigations were conducted at this stage.

So given that I think I have managed to tick off the boxes for every procedure I could find from the forum here and that the smoke remains. I was hoping as a last ditch effort if anyone had any further suggestions before I head up to Diesel Australia for an injector diagnostics test. Does anyone know how much I would expect to pay for such a test?

Given that a) I am not a mechanic although I do study to work in small spaces with high speed drills and b) the pressure that are present in the rail can injectors be replaced by someone at home? I suspect the answer is No and that I should leave this one to the professionals although given the current student status I am trying to keep doing most things on a shoe string budget.

Finally I just want to say a huge Thank You to everyone who contributes to the forum and spends their time helping everyone else out with your expertise and insight. I have found it invaluable myself and have definitely learnt a lot over the past few months from following the conversation and have attempted successfully many things I wouldn't have thought to do myself previously.

So if you haven't drifted off to sleep please feel free to contribute.

 

[jjohn]

Wow, I'm impressed. You do study.
It seems you've covered all bases.
Apart from the rough idle, and you mentioned it occurs again at the end of the day I would have said the early morning white smoke may be condensation until warmed up as any vehicle does.
I can't advise you any further as you've covered everything I would have.
Sleeping brains will be along soon enough.

It is a great forum, as evidenced by your ability to gather so much from it.

 

[joe2006]

I can't say welcome to the forum because you have obviously been around for some time but that is some inaugural post.

Sorry I can't help but agree with John that someone should be awake before long with what will hopefully be useful contribution.

 

[Old.Tony]

Welcome, and wow - not only an informative first post, but lots of testing done already and clearly explained - it knocks out a good few things to look at.

White smoke in a manual isn't common. Happens with the autos, because of the DPF, but the manuals only have the CAT. It's possible that a HO2S in your exhaust is mis-reading and telling the ECU that there's enough oxygen present to do the exhaust injections for CAT reductant delivery, but that's a bit of a stretch.

It could be the turbo actuator, and it's something I'd check - if it's underspooling enough to cause an impediment to airflow so much that the diesel doesn't even start to burn it's going to present white smoke (raw fuel, completely unburnt, whereas black smoke is partially burnt fuel). If this was the case, there'd be a good chance that you'd see either the intake hose between the charge air baffle and the intercooler (it's labelled in the pic in my garage as "turbocharged air") or the hose coming off the intercooler's outlet collapse from suction. Your intake manifold pressure (reported by Torque, use the boost pressure gauge) should be significantly negative.

Take a look at the little arm under the turbocharger actuator at idle, too, and make sure it's moving in and out a few mm constantly. If it's not - and especially given the age of the vehicle - your vacuum hoses may have perished enough to cause the turbocharger problems.

 

[slcrugby]

Thanks for the prompt replies guys.

OldTony thanks for the pointers. The actuator is consistent at idle with up down movement so hopefully that can rule out any issues. The pipe after the turbo expands which is confirmed by no significant negative values and positive values on acceleration through torque pro app.

Cheers for the feedback and suggestions.

 

[TigerST]

Welcome,

Fuel. Sounds like mine when I use 7/11 fuel. I'm trying to burn a tank of it now thanks to the missus.

 

[slcrugby]

Thanks tigerST I thought about bad fuel too so have tried various service stations mainly running Vortex Diesel but did try BP for 2 tanks with no change there either.

I have also added diesel power to the last 3 tanks.

Will be taking it to the diesel specialist this week and will let everyone know the outcome in case it helps out someone else in the future.

 

[TigerST]

No problems, Keep us up to date

 

[slcrugby]

Just to let everyone know reason for the white smoke and rough idle was injector 3. It failed the bench test. The other injectors were fine but needed new seals. Diesel Australia did the work and a good job although it would have been almost the same price to get a reconditioned set from Bailey's Diesel Group and have a whole new set installed.

Thanks for everyone's input.

 

[camo.b]

Good to hear your back on the road

 

[jld40]

Great thread - I've got very similar issues in a 2014 140kw manual D40 - about 10-20s of diesel smelling white smoke on a cold start and a more recently developed rough idle resolving when warm. 242000km

Mods / tests
- EGR plate (reduced black smoke to a bit of haze only seen at night). I need to put some gasket maker here though as there is some boost leak evidenced by a new oil stain
- oscilloscope test - timing chain wear ok and no significant difference in cranking amps between the compression spikes - told this means compression is ~even across the 4 - baytech auto in SE Melbourne
- injector cleaner maintenance every tank; oil flush about 10000km ago and changes every 7.5k
- turbo seems to work fine w boost values on torque app up to 24psi from under 2k - replaced the pipes with aluminium ones and noted there's a small but significant amount of oil in the system. Stopped short of cleaning out the intercooler.
- MAF cleaned and new filter recently / 240k + genuine fuel / oil filters
- 4x new bosch glow plugs ( I was sure this was the end of it but alas)

I guess the remaining things are ?SCV, glow relay and injectors? I'm reluctant to pull the trigger on injector work as the cheapest I could find a set was around the 2k mark plus labour... @slcrugby how did the reconditioned ones go?

Should I pursue a formal leakdown test first? While this picoscope stuff sounds reasonable I imagine the same symptoms could be a worn engine in need of reco; though it hasn't had a hard life with previous owner doing ~80k daily highway commutes / never off road / no towing.

 

[Old.Tony]

It's unusual for the SCV to cause white smoke ( = unburnt diesel). It's more likely to cause poor fuelling. Sticky injectors could do it, although with amount of injector cleaner you've been using I'd suggest this won't be the issue.

A blocked-up intercooler won't do it either, boost pressure is being read off the output side of the intercooler anyway so obviously enough air is being delivered by the turbo to keep that pressure up.

It can't be the EGR, which only turns on when coolant temp > 85C.

In the older cars (like mine), auto versions had a DPF - I'm not sure if the 2014 manual had one. An error in the DPF sensors could cause this - the result is the ECU opens the injectors during an exhaust stroke so that unburnt fuel can land on the DPF to consume the particles that have been captured by it. Easy way to check: get under the car and look for a widget in the exhaust that has a metal tube about 8-10mm diameter on the front AND rear, with these tubes heading up into the engine bay, and the device should also have 2 - possibly three - electrical connections. It should also have a heat shield. This device (in my car) is under the front passenger floor. If you have one of these devices, it could just be the sensors. Workshop diagnostic tools can turn off the "DPF Regen Needed" signal, but it will come back in 100-300km (random, as far as I know). You could try this, if the car has a DPF fitted, and if this trick works, you could consider either replacing the DPF ($4k from memory), deleting the DPF (about $1200 I think from yd25.com.au) or replacing the sensors with functional ones from @auggie (see this thread for details).