Direct Injection - Intake valves

[bennyr]

Hi Folks, just signed up here. Probably getting off on the wrong foot. I don't yet have an NV but would like to get one soon. It seems difficult getting some technical information. I understand the V8 versions of the NV vans have direct injection as does the current Titan. I know with early versions of direct injection engines soot build up was a problem on the intake valves. Is this a concern with the NV vans? Any insight is greatly appreciated. Thank you. Also, is it true that Nissan has discontinued the NV vans in the North American market? Should this be a concern? Thank you much.

[aztec]

Reasonable question.  Depends on who you ask.  If it bothers you, run heavier, low volatility oil, add a catch can to the pcv circuit, and add techron every few thousand miles.

[bennyr]

Thanks Aztec. Do the catch cans make a big difference? I do remember hearing about them.

[radin2son]

Aztec answered the first question. 

 

2021 NVs are being built. Check Nissan Commercial for info. 

 

There seem to be more commercial use NVs on the road. Maybe the delivery service has scooped up all the euro style vans leaving NVs for tough duty. 

[TopFuel]

Here is a video link to a 2018 direct injected 44,000 mile VK56VD engine. The cylinder scoring problems are in cylinder number 7. That is the rearmost cylinder on the driver's side of the engine. Examine the PCV plumbing and vapor distribution dynamics on each side of the VK56VD engine. I own a new 2019 VK56VD. Using my God given common sense and understanding of gravity and fluid dynamics, I have decided which cylinder I believe is going to carbon up first, worst, and also operate at the highest temperatures. 

 

Every catch can video I've watched is showing the cans are for a fact filtering out and collecting a percentage of the oil vapor contamination. 

 

Uncertain of the implications of installing catch cans while the engine is still under warranty coverage. 

 

https://www.youtube.com/watch?v=9-OYXvWVTzQ

[bennyr]

Thank you. Good info. Wish they'd change the design of the direct injection engines.

[aztec]

Catch cans are another "depends on who you ask" question.  Some people swear by them, others think they are a waste.  If you don't hack up the PCV plumbing installing it, or source spares for any lines you do chop, there is no way for anyone to tell it was ever installed, so warranty is not an issue.  I have seen no claims they hurt, plenty they help, and plenty they are worthless.  I run techron as preventive maintenance.  I know it works as I've fixed injector issues with it.  Redline is another brand that uses the same solvent.  Someone told me the concentrations are higher in redline, and I've had success with that as well.  Try a Titan forum for more in depth discussions.  Same motor, broader audience.  Your best defense is always going to be running quality fuel.  Alcohol free if you're lucky enough to live in a place where reason prevails over political idiocy.

[bennyr]

Watching that video talked me in to the V6 engine with Multi Port injection.

[TopFuel]

Yes, the factory PCV hoses can be disconnected, rotated, and easily and plumbed into a catch can system. Fuel system additives will only contact the bottom of the intake valve.

 

In the '70's GM took Oldsmobile gasoline engines and retrofitted them to burn diesel fuel, instead of going with a "clean sheet" design. They were a disaster. Now the process seems to be flipped with diesel style direct injection of gasoline, but using a spark plug to initiate combustion instead of cylinder temperature. On turbocharged GDI engines (looking at you Ford) low speed pre-ignition has also become a problem. 

 

Bennyr, I would have infinitely preferred a port injection system over GDI but I needed and immensly enjoy the torque and acoustics of the V8 engine. I classify cleaning the intake valves at 50k intervals as a DIY preventative maintenance procedure. Not happy about it, but while deciding on which van to buy, I didn't want my feet to be the first thing to arrive at an accident.

(Looking at you GM.) 

[bennyr]

Great post. I remember the diesel fiasco of the 70's. Yeah, I'm old. It was a great analogy to what's happening now with the DI system. I'm a little surprised there hasn't been a class action law suit against auto makers. I know it's not just Nissan. In my book, it is a design flaw. If nothing else they should redesign the engines and incorporate an injector upstream of the intake valves to wash them off as some automakers have. In the meantime we are stuck with a flawed design. I totally understand wanting the V8 though. I'm not aware of 2021 NV's being built. I haven't seen the commercial and I don't see it on Mr. Google. Perhaps for other markets other than North America.

[radin2son]

Not a “commercial.” That would ruin NV’s “what’s that” reputation. 

 

I meant go to Nissan’s Commercial web site or google 2021 NVs. 

 

Misinformation on on my part. I can’t find 2021 NVs mentioned on the Nissan site. Another site says they are being built but cost more. Another says production will cease summer, 2021. 

 

 

Edited October 13, 2020 by radin2son
The older you get, the less well you see.

[TopFuel]

Thank you bennyr!!  I too am an old guy.

I am currently reading through the Titan owner forum threads concerning the GDI issues. IMO, Nissan is being very proactive in replacing defective engines. I'm a mechanic, not a lawyer, but this seems to be an intelligent business decision to avoid class action lawsuits, while retaining consumer confidence. I agree, this is a flawed design bought about by CAFE and emissions standards. The VK56VD also has a computer controller VVEL variable intake valve timing lift apparatus somewhat similar in theory to the BMW vanos system. 

 

Sad. The engineers know how to built a 2 million mile class 8 diesel and an automotive 400,000 mile gasoline engine. They just can't do that while also having the exhaust pipe emitting cleaner air than what is flowing through the intake air filter. I used to buy Cummins powered duallies. You couldn't melt a diesel and pour it on me today. The VW Dieselgate was the most well publicized, but every diesel manufacturer (that I'm aware of) was fined for emissions violations. Caterpillar threw up their hands and walked away from the over the road market. Navistar (International) tried meeting the new diesel standards with copious EGR and a seventh injector spraying raw fuel into the exhaust (instead of DEF) and lost over one Billion dollars... along with their reputation. The EPA fined everyone. Bottom line was the ridiculous standards could not be met without cheating. As a bonus, 18 wheelers went from getting 6.5 mpg to 5.5 mpg or less, plus drivers were forced to park on the shoulder of the road for 30 minutes while their engine went through a forced regen process. 

 

Sorry to go off topic. Just some of the backwash as to how we got to where we are today trying to burn gasoline like it is diesel. 

[bennyr]

Thank you, not so much off topic. It's what's led to this whole problem. I wish the government would let engineers engineer. I also had a Ram with the 5.9 Cummins. I wish I never got rid of it. I just think auto makers should be redesigning these engines to alleviate this problem. Maybe they're working on it but this engine has been in service for several years now and seems to be continuing in to 2021. Would sure prefer the V8 to the V6 but I'm not sure I'd want to mess with the valve cleaning.