rich running 912E

[sportline]

What do I need to look for/adjust for the mixture control as it runs too rich and smells of unburnt gas at idle. It seems rich from startup cold to warm running - CHT sensor or? I do not think the cold start valve is leaking - or just injectors that do not atomize fuel properly.

Had been sitting for a while, and going through it all - fresh tune-up and valve adj.

Ideas?

Thanks

[WFBowen]

sportline:
I had a similar over-rich mixture problem with a 912E that just wouldn't lean out. You've probably done the following, but double check:
1. Timing; being absolutely sure your vacuum cannister on dist. is functioning and your temp sensors are good.
2. Check function of auxiliary air valve - make sure it's open when warmed up. Double check your grounds, especially the little spade connectors above the fan area (towards pass. side) under the large wiring loom.
3. Test the cold-start valve (5th injector) for leaks. You can temporarily pinch-off the fuel supply line to see if it makes a difference.
4. Check your plugs after a warm run - if it looks like all of the cyls are over-rich, it's probably the airflow meter (this was the problem I had.) Check the black plastic lid/cover on the AFM for signs of removal. If it looks like it's been off, chances are that someone tried to re-adjust for "better performance" but usually botched everything up. Also, these mechanisms will wear out over time. The system is designed to default to rich, "limp-home" mode when major components fail. My car was "eye watering" rich - just this side of spitting out raw gas through the tailpipe. After putting on a new AFM, everything was immediately correct - without any adjustments, etc.
Hope this helps & other "E guys" can add more info.
Bill.

[sportline]

It's amazing what an extra pair of eyes and hands can do! Took it to my local pcar shop for an hour to see whats up - found an open vaccum port at the back of the intake (facing the front of the car) with nothing attached to it. A short length of hose and a plug fixed that and then new seals on the oil breather cap and - magic - works like a champ.

Simple fixes can make the big problems go away - if only it was only this simple.

I looked and looked for an open port or leaking line and would never have found this - something to think about.