I'm honestly not certain, but yeah I do think that guideline I mentioned is for an engine at idle speed. I'll try to check mine and report back.

 

Yet another update.

I had the chance to spray the engine with carburetor cleaner to see if I can find any leaks and it seems like I could not identify any leaks on the in take hose,
throttle body, EGR valve etc.
Car is running smooth as usual, yet P0171 and P0174 keep coming back every time I restart the engine for the second time after erasing the code and resetting the adaptation.

However, I am not sure if this could be the cause of the leak, but I have noticed that the engine oil filler neck was loose.
The filler neck has a small clip at the bottom that clicks into position when seated correctly, but on my vehicle, I had to tighten the neck way past the "click" in order to secure it in position.

But I some how doubt that this could be the issue as I recall my engine running rough last time when the engine oil filler cap was not closed properly.
My engine is running very smooth despite the check engine light. Unless it was the check engine light, I would not have noticed that the engine was running lean.

 

The oil filler neck being loose can definitely cause an air leak, which would give you those lean codes. No guarantee that was the only root cause, but it could be. Let us know if that clears it up. You should know in 100 miles or so.

 

I got the same codes right after my previous response.

Have you done a smoke test?

I purchased the following to do my own smoke test and these items worked great. (I purchased the smoke machine vs. making one to make life a little easier on myself)

https://www.ebay.com/itm/283210079548



Found a leaking EGR valve and a leak just before the throttle body.

I just passed the yearly emission inspection and hopefully all is good.

 

Thanks for the information, this smoke machine is quite affordable.
FYI, I did the carburetor cleaner method to identify any leaks, but I could not find any. I think this machine should do the trick.

I am also waiting for the new oil filler neck since the current one is loose. I have tightened the current one so that it does not wobble.

Interesting thing is that when I clear the code, it does not appear until I restart the engine.
I drove all the way to Vancouver Canada yesterday after clearing the error code and it did not comeback until I restarted the engine at Vancouver.

 

Codes often won't come back until 2 or more drive cycles.

 

YYet another update.
I made a Smoke machine with a soldering iron and baby oil.
First of all, this homemade smoke machine worked great, creating lots of smoke, but there are a few things I would improve on it if anyone wants to try it at home too.

The lid is metal, so obviously, the lid started to get hot due to the soldering iron, and that melted the glue gun material causing the smoke leak.
I would use rubber grummets next time.

However, as for the air leak, I found three leaks. Two air leaks were on the intake hose (Red arrow below).
Both were minor leaks that I had to focus on to notice. I am unsure how to tighten the clamp as I had experienced cracking the hose before by over-tightening the clamp.
I wonder if I should use some sealant before tightening the clamp.
The second leak was between the MAF sensor and the intake pipe, where the screws are not fastening tight. I have glued the screws with JB weld, but it is still not enough to hold the MAF sensor tight enough. ​​​​​​​



The third air leak is around the loose engine oil filler neck, which I already have on order.

Overall, there was nothing dramatic. The leaks that I found were so small that I wonder if replacing the air intake pipe will solve the P0171 and P0174 issues, but I will update once I have replaced the air intake hose and the oil filler neck.

 

I did mention those earlier. Think what a tiny hole does in a straw when drinking. Same issue. It does not really take too much to be an issue.

 

Two things cause these codes. Air leak down stream of MAF and low fuel delivery. What is the fuel pressure? How clean are the injectors? How is the fuel filter?

General Disclaimer: I may be wrong.

Jeff

 

For sure on fuel being a cause of these too. My persistent lean codes didn't go away until I replaced injectors after one failed. rud3dog has 3 air leaks though so seems prudent to go after those first.