There's a big chunk of material missing from the outside layer of the intake manifold. It looks like maybe someone tried prying it off or something. I sprayed a decent amount of starting fluid at it with the engine running and the engine didn't move from idle at all.

 

Whatever, paint if you don't like the look. Did you have the P0171 before you pressure washed the engine?
If not, look at possible causes for P0171, that would correlate with a pressure wash. Btw, wtf is mounted on the rear of your valve cover?

 

Okay, cool. I wasn't sure if the cracking was important or not haha. I'll just leave it. It's hard to see, anyway.

I did not have the P0171 before the pressure wash. I was code free until the car wash incident.

I appreciate your image with all the info on it. I know I need to keep pressing on... I feel like I have dealt with so much in such a short time of owning this thing.

I have two new O2 sensors but wasn't planning on installing them yet (waiting until after this tank which has fuel system cleaner in it).

I tried checking my fuel pressure but the loaner gauge set I had was messed up (pressure release plunger was missing a retaining clip). I'll check it again when I have time (with a different gauge). When I tried the first time, the pressure went up to about 50PSI and then quickly dropped to 42-45PSI within 30 seconds or so, I think. Could have been the gauge, but I'll update when I check it again.

I have a crankcase breather filter on the back of the valve cover. It's a cute little guy.

 

You missed it. What would cause a P0171 with water?
Rule out:

• Intake leak
• Oxygen sensor
• Exhaust leak
• Incorrect fuel pressure
• Lack of fuel

That "cute little guy" is going wreak havoc, probably took in a lot of water during your pressure wash. Btw, CRANKCASE TO CAI CONNECTION=PCV.

 

Ahh... I am starting to catch on, I think. So by me not having the breather hose connected to the CAI, I'm messing something up? I was wondering about that.

The breather hose would have suction pulling from the intake tubing. There is another PCV from the back of the valve cover going into the intake manifold, I think.

Is there actual harm in losing the vacuum connection from the breather? Does my set up with the breather filter lead to air being sucked into it and causing the code? Would the car wash incident further the issue?

I was careful to not blast the filter directly but imagine some water could have gotten in (side note).

I don't know all that much about this stuff, so I appreciate your generosity in helping me understand lol.

 

Here are the two spots. Is it sucking on the right line so the left filter (old hose) is pulling in air?

 

Yes there should be a port in your aftermarket cai for a hose connection? Put that on your to-do-list. In the meantime, Did you check under the cops? / Clean/seal the FI connectors?
Stick with it, you could be a Hummer MasterTech.

 

At idle, the manifold vacuum is high, which would draw in a large quantity of crankcase gases, causing the engine to run lean.

 

A high vacuum from the manifold makes sense, which would totally take in a lot of air through the breather filter instead of metered air being pulled through the intake tubing into the breather tube and back into the manifold. Thank you for painting the picture for me.

I actually made my own CAI and modeled it after a K&N kit for a 2008, which comes with the mini filter (I think). There must be a different design with the later manifolds which allow for the breather filter. I will buy a nipple and install it into my intake tubing so I can run a breather hose to it. Hopefully that'll solve this issue.





There was definitely water in the holes with the COPs. Thanks for the tip on those. The front hole has a lot of rust in it and the rest are decent looking (but still water in each).

I have not done fuel injector connectors yet. Those are on the list. Does the intake manifold need to come off to access them?

 

I did some barnyard craft work and solved the vacuum leak (thank you Hummerz). I cut up an old spark plug, found a tight fitting nylon washer, applied some RTV, and hammered the sandwich together on the coupler just before the throttle body. The lean code is gone and hasn't come back. Now the P0137 code is pending. I cleared the pending code and unplugged the battery. I'll see if it goes away on its own. If not, I imagine the O2 sensor is bad.



3.5-inch silicone coupler, cut up spark plug, a nylon washer, and some red RTV.

Outside view.

Inside View.

"fixed" hahahah