There is no seal on the plunger stem at all. It just moves up and through the aluminum coolant housing.




There is no gasket sealing the stepper motor assembly to the coolant housing.

 

That’s good info about the EGR.

So far lean codes are not back and the fuel trims are perfect.

 

Interesting in seeing the difference on the new/old EGR smoke test. My EGR with 120k smokes less than that new one. I used some Gasket sealant around mine, but I still get very intermittent Lean Bank 1/2 codes. I've monitored the fuel trims and they are mostly under +/- 10% at idle and 2-3k RPMs. Occasionally they will spike, trigger the warning, then a couple of drives later the warning light is gone. Monitoring the trims, I'd say it's idle that's causing the trigger, and usually when the engine is warmed up. However, there isn't a consistency or pattern that leads to the cause. I've just changed my battery out so I'll see if that could have been a cause.

 

My LT Trim for bank 1 is typically around 9-10. Bank 2 is around 3. Does anyone have low LT fuel trims on both banks? Maybe higher LTFT is normal.

 

So much to track down this incessant code. I will have to go back through the thread to see how y'all have resolved the issue. I still have the codes, but there doesn't seem to be harming the vehicle, at least mine.

 

Just be aware, running lean for an extended amount of time can burn your cats up. That happened to me when it took me 6 months or so to fix an off and on lean issue.

 

Lean would not harm cats. Not in the least bit. Rich on the other hand......

Weird to think of EGR exhaust being unmetered since it is a closed system, the EGR, post MAF. But I guess it would make sense since it is technically excess air the engine is not anticipating the recycling of. Like a hole in a straw, in a way. Maybe at 200k I should replace mine - noticing my economy is down and oil changes are producing carbon rich used oil.

 

How lean/rich conditions affect cats is a pretty complex topic. Many do say that lean mixtures can't harm them, and on the surface that makes sense. Less fuel = less work for the cats so they couldn't be damaged right? However, in operation in an engine under constantly changing conditions, it's not so simple.

Here's an interesting discussion on the topic:
https://www.reddit.com/r/MechanicalE...re_affect_the/

One engineer had this to say: "An aspect of three way catalyst that is unknown for many is that it is able to store oxygen.

Lean mixtures would create a huge excess of oxygen that will be stored in thr catalyst, if this storage reaches very high level the catalyst could be endangered:

At later stages where AF is rich or stoechiometric, this oxygen storage will react with carbon particles in the cat and will result in exothermal reaction (heat releasing reactions).

Having high rates of such reactions will lead the catalyst to act like a burning furnace and eventually let it explode."

 

For those wondering about EGR smoke test leaks.... apparently this is normal. And sealing it up is a bad idea. In short, they are designed to leak to bleed off vacuum. Odd... I know...

https://www.rangerovers.net/threads/...testing.87586/

https://www.z28.com/threads/egr-valv...o-block.25269/

 

This was a great read!!!

​​​​​​So OP @droolyFace all in all what you think was fix for your codes and get fuel trims on a perfect range? The upper intake gasket?

Thank you