Possible Fueling issue? D40 2006

[Kzin]

Hi all, I'd appreciate some advice on this, have looked all over the net for similar problems, & tried many fixes but to no avail, I'll list what I have done below

My Navara has the following symptoms:

Note: there are no Codes
At cold start there is no power & black smoke, when first trying to accelerate. If I lift off the accelerator then try again it will come right after some lag, but its as though the boost comes on all of a sudden.
Power is quite flat even when warmed up.
When warm intermittently when accelerating power can come on suddenly after some lag.
There is injector rattle when accelerating, weather warm or cold
The idle is a bit rough, but not stalling rough.
Starts fine.

Using The Nisscan software I see "Pump Current" value of ~1389mA at Idle The manual states this should be ~1600 - 2000mA
Also at 2000RPM It is not changing & should be 1500 - 2000mA
Testing the voltage on the Fuel Rail Sensor I get ~1.5v at idle (is in the Correct range) but at 2000rpm it reads ~1.66v the correct range is 1.7 - 2.0v

With Torque on android I'm seeing Rail pressure of ~4200psi At idle up to a max of ~23000psi driving, Idle seems to be in range, but not sure about the driving figure.

I have changed the SCV, turbo vacuum solenoid valve, Boost sensor, MAF, vacuum Hoses, injectors, fuel hoses from filter to engine & both fuel filters.
Cleaned the Inter cooler, & Cat.

Am I correct in thinking that the above measurements, indicate Low fuel pressure, along with the injector rattle?

 

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[Kzin]

Hey thanks for that, but the EGR is blanked already, & the black smoke goes away once you get down the road a bit. I'm going to check that there is no leakage from the fuel rail pressure release valve, next.

 

[Old.Tony]

I think you need to examine boost control. Fuel rail pressures sound about right, that's how my car does it too. Typical mid 4K's for idle, up over 20,000 psi for pulling up hills (I don't drive it hard).

Monitor the boost pressure. It should respond fairly quickly to demand especially with the revs above 1800rpm. There are a couple of things that affect boost:

* Old/cracked/hardened vacuum hoses. Your car will have one vac hose running across the top of the motor from the vacuum pump on the vehicle's right hand side and this will go to a valve on the intercooler hard pipe called the "Boost Control Solenoid" (BCS). There will be another hose going from the BCS to the turbocharger actuator. If any of these turn easily on their joins, they'll leak vacuum and the turbo won't be controlled reliably.

* Faulty BCS. Unfortunately this is common. My own failed me twice, I now use a Tillix valve and have no dramas with boost at all. You'll know yours is faulty if the hoses are ok and the boost level isn't rising under engine load but the turbocharger itself is still ok.

* Failing turbocharger. These unfortunately cost a bit to replace, but I'd recommend getting one from a Honeywell Garrett supplier rather than a dealer (who will sell you a Honeywell Garrett unit anyway). Check yours thoroughly before giving up on it - shaft wobble, and check the inside of the hose going to the intercooler for any flecks of metal.

You could also do boost leak checks (black oil is emitted from leaking intake hoses and joins). Cleaning the intercooler will also help (petrol is fine, just give it an hour of sitting with the two ends open once you're done cleaning it).

 

[Kzin]

I think you are correct on the boost, I have noticed a Hiss near the Turbo, and getting under there can see soot on the exhaust side of the turbo core where the vane actuator passes through, A boost leak perhaps causing lag down low, & then feeling a bit dead once the boost comes on as well, as some is coming out, I have also noticed that the Actuator stop screw is missing! could that cause the vanes to close too far & not boost at low revs?

But yeah definitely Turbo...

Going to pull it off tomorrow, will post pictures

 

[Kzin]

Bit of an update.

When I re-built the engine I replaced the turbo core, as I noticed (when cleaning the vanes) that the original exhaust side had some chips in the fins.

So Removed the new turbo core, and put the old one back, and it is running better. the new one definitely seems to have been leaking out around the vane actuator.



You can see the soot round the under side.

So that has cured the loud whistle, and the huge lag on acceleration. But... see next post.

 

[Kzin]

I still have the issue of noisy injectors on acceleration, & pulsing (hunting), & it will die sometimes at idle.

But I think it is air in the fuel line, Because there is air in the fuel line.

I have Replaced the primer & filter with Nissan genuine, all the fuel flexible hoses & clamps, from the one just before the water filter (passenger side of the engine bay) to the engine.

I pulled the tank & checked all the pipes & etc. it all looks good.

If I blead the air out and go for a drive it will run good, but the next day the air is back and it gradually gets worse.

Yesterday when I was replacing hose clamps, I removed the hoses from the engine to the primer, I put a rag under them to absorb the fuel, but they were empty. but there was still fuel at the other side of the primer.

Could there be an air leak at the fuel pump? there is no leaking fuel.

 

[Old.Tony]

The fastest way to find an air leak around the fuel pump is to overprime the system. I had the water sensor incorrectly installed on my filter and air was getting in, allowing the fuel to drain back to the tank overnight (made starting difficult). I should have paid attention to the position of the sensor's electrical plug (which is supposed to line up under the knurled knob on the side of my filter, but wasn't at the time) but because I didn't, I decided to overpressurise the system to see where the leak was coming from. Less than a minute later, the filter was dripping diesel and I found the leak.

 

[Kzin]

OK, thanks for that, but After pressurizing the tank, I have found no leaks. But I suspect it may have been a bit of a red herring. I'll start another thread on the turbo...