Nav loss of power under load & clouds of black-gray smoke

[bringthenav]

My Nav D40 Manual 2.5L Diesel Navara i bought under a year ago has 300,000 on the clock, still goes alright around town.
Lot better when i bought it but not for long, slowly getting worse

It had this issue when i bought it i think, but not bad at all, i didn't notice or know about smoke, it didn't lose much power on freeway hills under load, then it slowly got worse over 8 months ove owned it, if it gets much worse i could be off the road.

Keen to get to bottom of it !!

It will display following symptoms:
After going up hills at say 50-60kmh typical local speeds then coming to a standstill... the engine appears to shudder for 10 or 15 seconds (the gear stick can be seen shaking about),

starved of fuel under load? or not burning diesel right from something unknown.. not sure?

Itll blow some smoke under heavy pedal pressure under load.

Then when moving off after the hill after its stopped shuddering about (or before that) it blows a huge cloud of dark black smoke on take off.

When cold and not warmed up much yet, it will shudder worse if coming to a stop after a hill, and then not take off well and blow smokeif stuck at lights etc while moving off still on a hill or under some load.

When planting the foot a fair bit to get up to decent speeds to negate town driving conditions itll blow a fair bit of gray or some amount of black smoke under load or fairly hard pedal pressing on accel until being light on pedal after gear changing and at cruising speed.

On the freeway if going up a hill at 110 itll lose alot of power after less than a minute, a blow copious amounts of smoke, mostly gray bit black maybe, and lose alot of power, even gearing down i wont be able to go faster than about 90, with smoke pouring out... And then on the flat again i can reach 110-120.
I noticed in testing on the flat it doesnt even want to drive much faster than 120 despite obviously not needing to, it would be blowing smoke and losing power if i try accel up to 120+

When i got it the first couple drives on freeway im pretty sure it had alot more power up hill and wasnt really doing this, but i noticed it was a bit gutless.

I have done about 3-4 fuel treatments, changed the fuel filter, changed the oil (bit overdue again i reckon its been about 7000-8000+ bit busy cash strapped etc, will do shortly.. i meant to do it by 5-6000)

Ive heard of this problem a bit before recently joining the forum while i was treating the fuel and doing the filter i looked it up a bit on line.

Hasnt been scanned for codes yet, but i have had Cel thrown a few times then go away and i have hit limp mode on hard accel a few times in recent months.. with or without a code on the dash..and had to pull over. I noticed if i turned off the engine & restarted it limp mode was gone and i can drive normally again.

What are some things it could it be?
Bad fuel pump? * I Suspect it
Blocked cat or dpf? *I suspect it
Suction control valve? *I suspect it
Electrical issue ? *Could be
Injector/s? *Maybe possible

Some good advice & your stories people of similar experiences and what it was/how u solved it would help alot. Thanks

 

[Old.Tony]

Early manuals didn't have a DPF (anything from about 2014 or before, I think). Not sure on the later ones.

To me it sounds like you have two problems, one quite common, the other not so but still happens. Thankfully they're not difficult to fix.

First off: if it's blowing black smoke it's got plenty of fuel. Don't sweat on that. I'll get to that later, let's look at the issue of planting your foot and having it go into a limp mode without a code.

The usual culprit for this is a damaged SCV. They sometimes get dirty and injector cleaner will sort them out (particularly if it's hunting at idle, not a steady rhythym) but since you've done that already I'll assume the SCV is damaged. Thankfully it's not too expensive, but you need to check if yours is a long or a short one. Here's two on eBay - I am not recommending these particular sellers, just highlighting the difference between SCVs:

https://www.ebay.com.au/itm/3943098...1wuneSEZ5x8FsSR6RnqPsWKw==|tkp:Bk9SR5iItpDfYQ
https://www.ebay.com.au/itm/1131475...fk0KWrP38G9uZT1wDiTmRqGQ==|tkp:Bk9SR5iItpDfYQ
Now, the power & smoke issues could be either a faulty EGR valve (particularly because your car shakes after a heavy run) or a failing BCS (not as likely but we still need to test this).

EGR is really easy - block it off. If yours is 2014 or older, you won't have any sensors and blocking it won't throw an error. It's easy: replace the gasket on the intake manifold side of the EGR tube with a blanking plate. It's really that easy. EGR should not flow at idle and a sticky valve could let it get in. At higher throttle levels you shouldn't have huge EGR flow but it might be doing the wrong thing: block it and see. If you still want the EGR to be functional so that your car complies with emission control standards, you may have to replace the valve.

The BCS is the little guy that controls turbocharger boost levels in the D40 (which has a variable vane turbo). If the BCS goes south your turbo won't boost much (if at all). The car will be sluggish and blow smoke. Test this: connect the vac hose that goes over the top of the motor directly to the turbocharger's actuator and take the car for a drive. If responsiveness improves you've got a faulty BCS. Note that without the BCS, you will overboost plenty and risk popping hoses - I've done that before - so just drive it enough like this to prove the BCS is faulty and stop.

You then have two choices: replace the BCS with another unit (eBay for under $40, see below) or go to a Tillix or Dawes valve, which removes the ECU from the equation - but you'll have to run slightly lower boost settings so you don't upset the works.

https://www.ebay.com.au/itm/1740739...GAOBYeTUh02J4O1esrOya7CVcrIC|tkp:BFBM-JGWkd9h
Hope that helps a bit.

 

[bringthenav]

Hi Tony. Thanks for the long reply.
Yeh that helps alot.
I should have mentioned at the beginning its a 2007 & vsk spain.

I'll try w replacing the scv,
Would the scv be short in the thai & long in the Spain is a wonder?

I have a new short one i bought a few months ago, haven't got round to trying it but its worth checking out.
Maybe my current scv is rusty and original and running injector and fuel cleaners a few times couldnt help it.

I'll try fit a new scv. Should at least help and probably run a bit nicer.
Theres no idle hunting.
Starts great, idles great, drives okay til after any hill especially larger ones, and loses power on hills on freeways and blasts black smoke. Running a canopy, a constantly packed full heavy car and a bullbar so its probably almost under load all the time. It may already have a blanking plate for egr but maybe not, but came with a blanking maf cable thats supposed to close it & it def runs better with that on but still blowsthe smoke and has same issue, but probably not quite as bad.

I just read 3-4 other related posts after i wrote this post, and saw your info about trying a ecu fuel map reset with the battery. In 2 posts, and both guys said it solved the problem.

It may just be mostly or entirely pretty much having the same issue, being it seems like it maybe over fueling under load when the turbo has to work more.

I certainly dont feel like the turbo doesnt work properly at all, i hear it going & i feel its boost plenty but unsure of the boost readings at present if its running between the 18-21psi, but its certainly running okay far as i know.

I don't think my solenoids not working by any means but it may not be the best in the world & could be a factor.

I can try
1 The fuel map reset
2 The unplug the actuator vacuum and carefully putt up the street seeing if performance improves as i reach a hill, my street has a small hill if i turn right, if i turn left its a small downhill.
3 The scv replacement

Hopefully that will do it.
If I'm lucky in 15mins easy work with the fuel reset trick i'll be sweet & all i had is an overfueling problem.

The last owners spent buckets f money on it with lift kit it, heavy duty suspension upgrades & towing e brake gear, different wheels etc, they could have pulled out a plugin chip or cable out before trade in or something.

I do get terrible fuel economy from the start & it got bit better after a few injector, fuel sys cleans but could be blowing half burnt fuel out constantly.

No harm in trying the fuel reset brake pedal battery disconnect trick right?

Sounds easy and harmless to do.
Considering doing it now quickly & seeing how it runs after it.

Probably wait until morning after i might hear a reply back

 

[bringthenav]

I got the touchscreen double din stereo fitted, so wont need the inputting the radio code after, but i have it written in owners manual

 

[Old.Tony]

There's never a harm in trying an ECU reset. Just be sure to drive it fairly moderately for about 10 minutes then shut it down so the "moderate" fuel map is stored. I'm not 100% certain that Nissan make it save the info like that - but it doesn't set off alarm bells and isn't hard to do.

If you feel like it's getting good boost then the BCS is probably fine. It's more likely EGR getting involved.

 

[bringthenav]

Alright, i'll give it a try in morning.
So long as it can't harm none.
Kinda thinking u could be correct about it being EGR, it might be all sooted up and stuck & the blanking cable might only partially work or not at all, but certainly goes better after fitting it.

Also:
I found this video earlier while trying to search for videos showing the ECU reset u described in the other posts.

Shows a pedal dance type reset
reset recommended after fitting new parts like scv, fuel pump etc if when dont have a scantool to reset after fitting various sensors.
The get in close door, ignition on, 5 Accel taps in 5 secs, wait least 7 sec, hold accel least 10secs, let go when EML light comes on & then wait a couple mins while it flashes and relearns about all the sensors etc fitted to the truck, then turn off ignition to save.

Someone in the videos comments mentions it didnt work & found a forum saying do all that but also then hold the accel another 10 secs after all of that before turning off ignition & amother commentor said this worked after having the video way not work for months.

Do you know about this video one and this other extra pedal push anyone & if so is it different from the one u describe, or just do same thing?

Heres the link :

 

[bringthenav]

I'm inclined to just try the battery reset first.. maybe itll work, if it does i will certainly post my findings.

If no joy try the careful brief run with the solenoid actuator vacuum unplugged check for the moment.

Never know could then try the new scv, i think i need the long one, going off comments around the placefir the spain model, i'll look at it and know anyway before ordering.

 

[Old.Tony]

The reset technique is only going to work one way and the way you described it is what I've tried (if you don't get the timing right, it doesn't work). The battery-off technique just means you can do it without concentrating too much.

The cable device has to actually work and relies on the EGR valve actually remaining closed and not being stuck open because of soot caught in it. Blocking it off completely bypasses that issue and a 2007 model definitely won't have a clue that it's been done (no flow sensors). Do the block first, before the SCV.