hi..ST...you can pass a smog in CA if you have catalyst and oxygen sensor connected(even with higher fuel mix) but he is not in CA so the regulation are different in Canada i assume;-)
Also the fuel mix was never adjusted ,that would my 1st thing to go after since ha has check all of the above...
Ivan

car passed smog about 10 years ago....back when it was idling fine. It also had a cat back then.

So I played again with it this morning. I played with the mixture screw. I had the O2 disconnected and tried to see what reading I could get. With the mixture screw all the way in I was getting between 0.3 - 0.8. With the screw where it originally was I was getting around 0.03-0.06. With the screw all the way in it would not idle with the 02 plugged in. With the screw where it is it will idle fine with the O2 plugged in.

In every case putting the jumper in settled the idle right out. Could it be as simple as the ICV even though it passed it's bench tests? Anyone try using an non-bosch one (cheaper kind)?

Hi Old You basically did not adjust the fuel mix in 10 years? Correct? i suggest you you do the adjustment.
Set it around 1.0.... oxy unpluged.....
Are you now talking about mixture screw or idle screw??

here is some reading where the mix screw is located.

http://forums.pelicanparts.com/porsche-911-technical-forum/438195-idle-throttle-screw-setttings.html


and here you most likely have this plug still in .If not you just have to adjust it .If the plug is in you have to remove the AFM unit and remove the plug to access the adjusting screw for fuel mix.
http://img.pccreation.net/photos/201803031656443009.JPG

I have owned the car for 10 years and have never touched it. There was no cap on it so I am assuming a PO has touched it.

How do I set 1.0? 1.0 what? Volts?


I was talking about the mixture screw on the underside of the AFM.

ok now i know you know which mix screw .To set it you have to go to someone who has the gas analiser .Or you can play with it by listening to your engine .It has to be warm to adjust...oxy sensor disconnected and side plug jumped with your tool-wire.

Ivan

Unfortunately I don't have a gas analyser. I played with it and couldn't get a noticeable change by ear.

Just for fun I unplugged the CHT. It just belched out black smoke and didn't really idle. Just coughed. Mean anything?

My car will not start with the CHT unplugged.

How old are your spark plugs? If they are bad, even one, car will run terrible

Motronic really should not change much through the years. Must be something else. Do a complete tune up. That is what I did and car runs so much better . Also I installed correct 02 sensor.

Old..again if you disconnect the oxy sensor and insert the jump wire on side the idle should change ..Your??

Replace spark plug wires! Really!

They are about 30min old.

Depending on where the mixture is set disconnecting the O2 sensor does or does not have an effect. Jumping the wire always stabilises the idle out.

Ok..what i would really do..Find a nearby shop where they can check your fuel mix...you did a lot of things and even now you do not know what the mix is..That is very important for the engine running fine...and correct idle

Ivan

That was my conclusion as well. I will either have to wait and then go to a shop or order my own meter. Right now my car doesn't have axles, front suspension, brakes, or seats so it's not going anywhere soon.

it looks like you have something to do when is cold outside;-)

Ivan

+5C, sunny, and no snow here...unfortunately. I usually have tons of stuff to do when it's cold and snowy out.

Back to the question. If I had to buy a tool to check my mixture. Should I get a CO gas analyser (gunson gastester) or get some sort of a air/fuel guage perhaps even a wide band LM-2. I don't know much about these things.

My fuel pressure tester came in the mail. I tested the fuel pressure engine off, engine running, and vacuum disconnected as per bentley. Exactly on spec.

Search in my previous posts re surging. I had a similar issue and I tensioned the spring on the air flap in the afm. There were quite a few posts about the tracks on the afm being corroded and needing resetting. HTH .

AFM track has been 'shifted' over a mil or two.

As for messing with the spring I have read mixed advice over that. I will read more, however.