Hi all,
The car is idling well now. Thank you all for your input and to Sal for sharing his knowledge. I have the "least crappy" of the after market valves on my car while I hunt for an Bosch unit.

The IACV was the issue. I did test the valve electrically and measured the resistance across the pins as my test. What I did not do .. and what is the most simple test ... is try and blow through the valve when closed. That's all on me.

The IACV on the car was functioning electrically, but not sealing when closed. There were other adjustments done to the car to mask this issue, thus the excessive rich running condition.
The air-bypass valve was also leaking and I had cracks in one of the oil vent lines. These were great to fix, but were not the cause of the idle problem.

To further confuse the situation, I still have the high RPM miss over 6k ... but that looks to be unrelated.

A good lesson in the mess that can be made when tossing parts at a problem when full testing has not been complete.

Thank you,
Chris

That test is incomplete. The very simple tests referenced in posts #33 & #34, if done correctly would have found the problem. Try the test, since you have a bad valve. It would have saved you time.

Bench testing the valve only tells you that the valve moves from full open to full closed stop. What it does not tell you is when fully closed does it actually block air flow.

The after market valves leak/allow a ton of airflow to still pass through the valve even when fully closed. The Bosch OEM valves do not allow much if any air flow when closed.

So the testing would have told us that the original OEM valve was bad, that's good to know.

But then he purchased a aftermarket valve that does work and moves close and/or open but the valve leaks air when closed. This causes the high idle issue because these aftermarket valves are not to Bosch OEM valve specs.

Keep in mind these cars are more than 30 years old and often issues like this are caused by 3 or more failure conditions. It's not always just one thing wrong.

You can have air leaks, cracked hoses and such that tend to get worse with time. Then you suddenly have a idle switch go bad or out of adjustment. Or maybe the ICV craps out.

Diagnosing multiple issues at once is not easy and just throwing parts at the problem complicates things further.

Start by finding the actual issues one at a time and fix them as you go.

Most importantly, never assume a part is good simply because it's new!

I've seen:
- spiders nest in new vacuum lines
- new vacuum line 'Y' connectors that came defective and blocked.
- aftermarket parts that are not to spec as we saw here.

Chris,

Now you can go chase the >6000rpm issue. You have a decent WBO2 gauge now, start verifying AFR conditions next as follows:

1 - Set base idle speed at 900-950RPM
2 - Set idle AFR at 13.8 to 14.2AFR
3 - Drive the car on level road at 3000RPM in 4th gear, take note of AFR. It should be in the 14.4 to 14.8AFR range.

Do these next test then we can proceed to hi-load test for AFR.

I suspect possibly you are going lean at WOT but we don't want to test WOT AFR just yet. Proceed to testing part throttle AFR in steady state 3000RPM 4th gear.

I also explained how to do a cylinder balance test by unplugging one injector at a time at idle. Please do that across all 6 injectors so we know they are all functioning the same.

May be the new ICV was defective from start? I have heard of successful replacements with this aftermarket brand LOWE from Germany. You can find details and price here.

You like the OP, did not fully read post #20 referenced! Here's some help from the 2008 thread post #20;

http://forums.pelicanparts.com/porsche-911-technical-forum/360766-bench-testing-carrera-idle-control-valve.html

"This leaves me with a funny feeling that the DME controll lines (pins 33 & 34) are pulsed GND signal lines."

Good guess!

"But they could also be variable 0-12V analog but I doubt it."

Bad guess!

Most make this issue more complicated than it really is,
i.e. just check that the valve is clean and most importantly
that each winding (from the center pin) is about 20 ohms.

A very simple operational test:
1. Remove valve and fully close the vane and re-install
the valve without connecting the connector.
2. Start the engine and it should idle at a low RPM.
3. Connect the connector. The idle should come up to
the normal RPM.
4. Stop the engine and remove the valve and fully open
the vane and re-install the valve without connecting the
connector.
5. Start the engine and it should idle at a high RPM.
6. Connect the connector. The idle should go down to
the normal RPM.

Simple!!!
__________________
Have Fun
Loren
Systems Consulting
Automotive Electronics

You obviously read it in 2008 because you quoted it in your post #22.

A lot of time wasted in this thread by not fully reading posts, or understanding them.

Yes agree, that's exactly what I had him do. Install the valve fully closed and the non oem valve idled high when closed. This is a really good test.

Then he should have known that the valve was bad on 11/24, if he did the test correctly per the post #34 on this thread.

You've mentioned the adjustment screw on the AFM and adjusting the wiper inside.

On all the AFM equipped cars we've checked, we've had to physically adjust the clock spring several clicks to get the car close enough to spec in order to effectively use the adjustment screw.

https://www.youtube.com/watch?v=yQukm7lNux4

My personal car ran SO MUCH better and achieved a personal-best MPG on my latest 5k mile trip to RR7 and back.

Up to 28 mpg at 80 mph on wide sticky tires loaded down with two people and a ton of cargo. The worst was 20mpg when driving the hell out of it.

Only affects the idle, i.e. once the throttle opens it has no effect.

This affects acceleration, and mixture at cruise, but the O2 counteracts its effect when connected. Adjusting the wiper can be used to tweak emission test parameters.

The AFM spring was adjusted too rich for the air screw to have an effect, and/or the butterfly stop was incorrect.

Exactly

The AFM has 2 possible adjustments:
1 - The big wheel that controls tension on the spring. You should never touch this unless you know howto calibrate the AFR across the entire RPM range. If you tighten the spring it will effect the AFR across the entire sweep of the AFM. Set this very loose results in AFR getting richer and richer as air flow increases. It is possible to re calibrate the AFM with a WBO2 gauge and lots of test time.

2 - The wiper arm has a single screw that allows you to reposition the arm on the carbon. You can move slightly up or down the carbon track. This is useful for setting base idle mixture if the CO screw is all the way in or more than 5 turns out.

Bottom line is that trying to adjust these AFMs often results in fixing one condition but making another worse. For example you make adjustment to hit idle AFR and then find WOT AFR is out of wack. Or vise-versa.

That's great information. I need to dig out my old wideband and permanently install it in my car to verify I got as lucky as I think I did. The car has been running better than the last 70k miles as far as I recall.