Another black smoke thread…

[user 50884]

Thanks I’ll give that a go.
Read somewhere that disconnecting the electrical contacts to the injectors then doing a fuel reset might work as well.

I only replaced the injectors since I believed they might was causing the black smoke however that wasn’t the case. But yes the injector codes was updated after replacing.

Strangely no error codes at all

 

[Old.Tony]

Read somewhere that disconnecting the electrical contacts to the injectors then doing a fuel reset might work as well.

It might be worth trying if the simpler reset doesn't work, but I can't see a lot changing by unplugging the injectors (since they're newly installed, they've already been freshly plugged in so their electrical contacts won't be suspect).

Fuel metering at idle will mostly be a function of the programmed engine speed (typically 750rpm), the TCM and data from the MAFS. EGR will be off and not included in the ECU's calculations. Engine load (for air conditioning mostly) may play a minor role - but on my car, aircon ON doesn't raise my L/H figure much (up to around 2).

Have you cleaned the MAFS?

 

[user 50884]

Yep both tried cleaning and replacing it.

I’m a little bit suspicious about my valve clearance: (0.0 in front all)

I1: 17
I2: 25
L3: 17
I4: 31
I5: 23
I6: 31
I7: 17
I8: 25

E1: 17
E2: 25
E3 25
E4: 31
E5 22
E6 32
E7 22
E8: 27

Haynes manual refers to intake: 0.020-0.053
Exhaust: 0.030-0.063 with limits for valve tap at 0.080 & 0.090

Nissan service manual says intake: 0.26-0.34 exhaust: 0.29-0.37 (cold)

Wouldn’t a tight valve clearance cause a poor combustion? Potentially causing black smoke?

I also found injector 4 almost stuck in the cylinder head, lots of carbon build up the injector. Will clean and replace the seals.

Worth bothering about the clearance? I would have thought for performance and fuel efficiency a looser clearance is preferred?

 

[Old.Tony]

I wonder why injector 4 had lots of carbon - you've just replaced the injectors, they should be quite clean. Something isn't right in Cyl4. How's the intake manifold? Any build-up in there, particularly towards the back?

I'd adjust the clearances.

 

[Erick]

I would be checking injector four, recently replaced or not. Black smoke and carbon build up are the same problem-over fueling.

 

[user 50884]

From memory the intake wasn’t all that bad when I took it out to replace the head.

I’ve done the valve clearance and swapped injector 4. As well as fuel map reset both through battery method and with injectors disconnected. But she still smokes.. it isn’t crazy smoke, but enough to be annoying.

Last time I had a D40 like this the local tuner managed to remap it to run leaner and got it to run like a dream.

Unless I missed something obvious the only thing I can think of is that the overheating has lowered the compression slightly so it no longer matches factory tune..

 

[user 50884]

Maybe a random question but I'm looking at getting a common rail chip, more so just to use just for troubleshooting purposes.
Now all it seems to do is increasing the fuel pressure. You would think it would cause more black smoke? But does it necessary mean more fuel? or will it be the same amount of fuel, just at a higher pressure?
If the case is more fuel and higher pressure, how does the tuners compensate for that? Do they tune the throttle body to open more?

Perhaps in my case it would be better to find a chip that allows more air? Is there any throttle body chips going around?
I have seen these hiclone devices that you mount at the throttle body, supposly it allow more air to the eninge?

 

[user 50884]

So looking into the intake from where the throttle body mounts it definetly looks like there is some build up inside the intake.

I normally always degrease and clean the intakes when replacing cylinder heads. However maybe I did a slack job on this one.
It also looks like the egr is blocking almost 50% of the hole.. would it be worth cutting it off? The egr is blanked anyway.

Is there a carbon cleaner you can spray in to the intake or is the only option to pull the manifold off?

 

[Old.Tony]

In order to avoid problems, I'd only clean the intake manifold after removing it - because I'm paranoid.

Chips: there's a bunch of different ones. Some only change the response to the ECU from the fuel rail pressure sensor, which means the ECU thinks there's less pressure than it asked for, so it increases the pump's output. Standard laws of pressure in pipes works here: higher pressure means more flow through the same aperture. This may very well produce more (black) smoke.

There are supposed to be chips that adjust injector duration or the number of openings as well (longer duration or more opening times = more fuel) but these chips usually add extra boost as well, and they monitor EGT to ensure they're not overdoing things - if the EGT climbs over a certain level the chip deactivates, allowing the ECU to take control (something the cheaper, simpler chips like No Limits won't do).

 

[user 50884]

Alright I’ll take it out and give it a proper clean. The question remains if the build up is what causing the issue or if the issue is causing the build up. Guess I’ll find out once it’s been cleaned.

I was hoping to find a chip with a number of settings where the lowest settings would lower the rail pressure. Perhaps this can be done on request, I’d imagine that people with hot tunes would want to have a chip with modes so they could lower the performance if needed.

Everyone talks about SCV, what about the other sensor on the pump? Is that a common fault?

 

[Old.Tony]

The remainder of the pump on the D40 is pretty robust.

A really good tune (done on a dyno) will edit the ECU itself. Chips can only adjust a tune and react to the inputs it gets - like EGT, throttle, load, boost etc and make adjustments based on that. It's another layer on top.

To reduce smoke you could ramp up boost earlier (unless your car had a DPF that's been removed, in which case you could put one back in). More air will allow more complete combustion = less smoke.

 

[user 50884]

Ramp up boost as shortening the actuator rod?

I does blow a little less smoke if I bypass the boost solenoid but the smoke is still there.

 

[Old.Tony]

Ramp up boost as shortening the actuator rod?

I does blow a little less smoke if I bypass the boost solenoid but the smoke is still there.

You could shorten the rod yes, that's the cheapest way. Might want to prepare for popping the hoses though, at full song she'll make a decent amount of pressure in there. The other method is to edit the ECU and have boost mapped a little earlier but the limit retained.

It's a diesel though - without a DPF they all blow smoke at some point.

 

[user 50884]

I’m happy to give it a crack.

After cleaning the intake and putting the vacuum line straight on the actuator it smokes a lot less.

However If using the cruise control especially or just driving in 6th gear climbing a small hill, the engine will drop in power (like a minor limp) until you take the foot of the pedal and press it again.

Kind of like the engine is backing off from to much load.

Also the turbo is whining a bit after long distance driving..