koala

Looks like I need to go back in there and check my work. I didn't realize there was a rubber o-ring on the solenoids and now I'm paranoid that the new ones didn't have an o-ring, lol.

Edit- looked at the part diagrams again online. Looks like the o-ring comes with, guess I can just keep an eye on it for any oil leaks.

Joec500

I saw a pic of that part number on Ebay and I could see a brand new purple o-ring installed on that part number, so you should be good to go.

koala

Thank you, sir. I can't smell oil or see any drips in the parking lot, so I should be good. I'm also going to have the car up on the lift at the Porsche dealer shortly here so they can torque down these transmission bolts (LOL!), and they've agreed to let me get under the car while it's there.

Ducaiti999

Ok. After all the parts replaced so far and no change in idle stumble I have come up with one data point that confuses me. This thing will run great when the ambient temp is low and humidity is low. Today all day it's been right at 80 with sub 40% humidity. Runs great. I have seen this trend on at least 5 other cold snaps down here over the last 2 months.

AFR is stable
Cam angle is on target

Short term fuel trims stable within 4%

None of this is the case when the car is stumbling

So, what is that all about?

1st theory:

Malfunctioning injector on bank 2 causing a rich condition that STFT is trying to lean out.

Could it be that the air density being higher is allowing the car to not try to lean out STFT?

2nd theory:

Some sensor (COV possibly) that is affected by ambient temp is causing an intermediate vacuum leak?

I'm nearing my whit's end on this thing.

I do have 6 new injectors, I guess that's the next 2k parts guess to install.

Joec500

This sounds super frustrating, I like your Theory 1 I had this issue on my old N54 335 (I know different platform, but all ICE work on the same principals) I had a leaky injector causing a rich condition, it eventually blew out my cat on that bank. It was also intermittent.

Good luck and keep us updated. I am sure it's just one random part and when you figure it out it will be so satisfying.

mikeleal

Did you ever figure out the problem?

GermanCarFan1

Did you change out your gas tank filler cap rubber O-ring along with your oil cap O-ring? These are all related issues associated with "the stumble." People have changed these out and have seen a difference.

koala

I feel like this is the first I'm hearing of this. Two more parts to buy and replace in the never-ending quest to solve this stumble.