D40 Keep it simple

Hi
New to forum. Bought a 2007 D40 for my kids after forgetting I advised against it based on problems on websites. Forgetting that - I have always been a believer that the "problems" are solved by checking the simple things.
This website has been both helpful and confusing. The amount of "new injectors" and "injector pumps" is scary. Particularly when they did not solve the problem. I bought a hard driven ex-minesite ute.
First problem - no 4WD. Followed the manual right down to checking ECU readings. Replaced neutral safety switch etc. Checked transfer relays etc. Final manual diagnosis "continuity in wiring harness". Have no doubt that if this went to Nissan that would be result. Last minute "fluke" result... The transfer relays have multiple pins. One of the female pins in the harness was a little loose. Squeezed in with pliers and full 4WD - no problem since. Simple in the end but over 60 hours to eliminate and detect.
Second problem - limp mode- reset fuel learning and gone.
Third problem- Loss of power and black smoke- intermittent sometimes. Changed turbo boost control solenoid. No help. Manual was incorrect in terms of different suction working. New solenoid did exactly the same as old one. Had already replaced 2 vacuum hoses one of which was cracked. There is a 3rd suction hose down behind the others which is harder to find. That was cracked as well. That problem solved.
Real difficulty starting. Lots of cranking and finally start with absolute plumes of black smoke. Pump balloon soft. Seems to be losing diesel pressure but overfuelling at same time. ERG blanked. Replaced fuel hoses, filter and can't find any leaks even under pressure. Once vehicle is started runs absolutely fine. Good starting for 4 hours then back to bad. Replaced suction control valve (by the way it was "sticky". A bit of wet and dry sandpaper and it was as good as gold. Still replaced just in case.). No help. Now suspect that it is the pressure control valve leaking pressure.
No fault codes.
To start this it requires foot down on throttle and winding the motor for a long time when the starter motor is doing little work as the motor tries to start ..nnnnnnnng...nnnnnnnnnnnnnng............nnnnnnnnnnnnnnnnnnnnng Sound effects.
In hindsight all of the problems have been "simple"
I haven't "blanked" the pressure relief valve to eliminate that.
Once running- lots of power- no dramas - It has never been good on economy - consistently around 13l per 100km. Has new glow plugs. Another waste of money attempting to solve a problem.
Vehicle has done 240,000km but new head 220,000km. Little discernible bore wear etc.

Welcome to the forum mate, can you seperate your long post into paragraphs?, it will help any member easily read your issue and assist.
Cheers

Welcome to the forum!

It sounds more like an air problem than fuel. Sounds like it's getting all the fuel it needs.

I'd do the following things:

1) Clean the intercooler. It's not difficult, takes about two hours (which includes pulling the grille out to get to it and an hour's drying time). a few plastic pins, a couple of bolts, two hose clamps and it's in your hands. Use petrol and swish it back and forwards inside until you start seeing the actual fuel colour. Mine too 5 goes before I started seeing the red of the unleaded. Let it dry before reinstalling.

2) Clean the MAFS. While you're at it, maybe take the air box out and give it a good clean. Mine was full of every insect known to man and a few that must have come in on a spaceship.

3) Check the EGR. If the valve sticks open (which they have done in the past) and the EGR blank plate has developed a hole, it could be swilling exhaust while it's trying to start - it will be very reluctant to fire and with all that exhaust gas (relative to the air flow), the smoke plume should be visible from orbit.

It's also invaluable if you can get a $5 OBD-II bluetooth adapter (ELM327) and an Android app to read the codes. I use Torque - best $5 I've spent (on top of the cost of the bluetooth adapter). Reads your boost pressure (and a hundred other things) right out of the box. Examine that boost pressure and make sure you're getting some. You should get up around 18-19psi under moderate-to-high load.

Your fuel economy is in the ball park, so run that one off your list of issues/faults.

As you have found, fault fixing is the easy part, the finding is the hard part. The hours of looking, testing and yes, throwing some known good parts in to get a solid known good start point some times. And if you have to pay for those hours, it is not hard to see why people give up and trade the cars in for another one.

I am pretty sure your engine is the same as mine, the accelerator pedal is not physically connected to the engine. The ECU controls the engine to get it to rev as you have demanded, and the ECU knows what you have demanded by getting a signal from the throttle position sensor. So, holding your foot down on the pedal whilst starting may be having less effect that you think.

Lots of black smoke at start up is an over fuel situation. Being an ex mine site vehicle I would check what a mine mechanic would do to a car. From experience of a long time ago - check the air intake path. Snorkels are never cleaned out and yet the mines basically run all the haul roads as a light mud to keep dust down. But that mud goes every where. Radiators/intercoolers are best replaced, it is near impossible to clean that mud out completely.

Air filters are often the cheapest you can get.

My only suggestion is to clean the fuel tank out- physically take the tank out, flush the tank out completely and refit. Take the fuel filter out, siphon the new fuel through the pipes , disconnect the injector lines and pump new fuel through. Fit a new filter . That will rule out water in the fuel being an issue ( mines are notorious with their tanks for the smaller vehicles having condensate water in the tank. ) . That gives you a good start point.

Thanks guys. I have removed and cleaned the MAF, Intercooler, air and fuel Lines, air box fully out and replaced air filter. All good. The fuel tank was out last week to replace the float which recently came off.

The ERG blanking plate is only 6 months old but will recheck. Smoke is visible from orbit on start up.

Holding accelerator down definitely helps. It knocks and chugs for about 3 seconds then runs. With no accelerator it won't get to chug stage. Once started the motor can be immediately shut down and will start perfectly.

If it is left standing for 4 hours then back to hard start.

Will keep checking and invest in OBD-II adapter.

after the engine has been left for a few hours or overnight , have you checked the fuel filter primmer pump so see if its hard or spongy ? should be hard to push down and if not you have an air leak around this area. this will cause the engine hard to start.

Thanks Jonney
Yes it is slightly spongy overnight- pumping it up hard makes no difference to starting. Have replaced lines and hose clips.
I was suspecting the pressure relief valve on common rail- so will blank it off to see if still losing pressure?
Definitely overfuelling.

With your foot flat to the floor it's going to overfuel, guaranteed.

The big question - with all that done - is how many pumps does the primer need in the morning? If it's just 3-4 at the most then we're no closer to solving the problem. If you get to 5 pumps or more, the answer is an air leak in the fuel system, with air bubbles causing havoc in the filter + pump + SCV + rail. Planting your foot on the throttle opens up the number of injector cycles + demanded rail pressure = potentially more fuel than required.

Of course, "overfuelling" is a relative term in a diesel. Diesel engines are supposed to get complete lungfulls of air all the time. There is a throttle butterfly in the intake - you might check that this isn't sticking from gunk or something. The point is, "overfuelling" also can mean "under airing". That's why checking the EGR isn't open is important (exhaust displaces oxygen = under airing). Pull the hose off the front of the turbo and stick a plastic rod in (a clean texta will do the trick) and spin the impeller if you can't reach it with your fingers. It should spin fairly freely but should stop reasonably quickly. It shouldn't be too reluctant to turn. Something tells me this isn't the problem, but it's worth checking just to be sure.

Speaking of simple things, mine had trouble starting and it turned out to be the non return valve in the primer bulb.
It was passing and draining the fuel system out when left for a while. New bulb and it was all good again.