2.0 idles fast then not at all

[bobswei]

On my '74 2.0 that I recently restored. It runs very well but idles fast, around 1800 RPM. Fuel pressure is at 26 psi, idle on ecu is as low as it will go, air screw is all the way in. Now, after driving it till it's all the way warm, park the car and short time later, it starts right up but won't idle. It's trying to idle but will stumble and die. If you keep your foot on the gas, you can drive it and still runs great. Plugs seem like a good color, not to rich. Why, idle to fast, then not at all after stopping?
Maybe a cylinder head temp sensor? I've changed it twice. Any ideas?
Thanks

[Dave at Pelican Parts]

Sounds like you have a couple of different things going on.

First, you either have a vacuum leak of some kind, or your ignition timing is pretty far advanced. Double check the timing, then start looking for vacuum leaks.

Do you have any hoses that are not connected? If so, that's a problem. Does the decel valve pull air in at idle? (Check the hose from the valve to the air cleaner.) If so, that's a problem. Does the Aux Air Regulator close, or does it still let a bunch of air in even when the engine is warmed up? (Again, check at the hose from the AAR to the air cleaner.)

Second, your slightly low fuel pressure (should be 29 PSI) and ECU knob cranked all the way down means you are running lean. That would cause an erratic or very poor idle.

--DD

[bobswei]

OK, I'll start with the easy stuff. Vacuum lines are new (less than 50 miles on them) and gone over all the diagrams to get them correct. Even had the car at a Porsche repair shop to get it to run better. Decel valve at idle pulls very little to no air. More revs, I can feel suction. AAR pulls air at idle, from putting my finger over the hose end. But that causes the engine to slow and die. Haven't tried it with a warm engine yet.
Timming - more difficult. A few years back I put these two white marks on the fan. Don't recall why other than so many degrees BTDC. The photo shows, kind of how they are oriented with trimming light at idle. I would think, the shop double checked timming when they worked on it but still suspect.
Did this add any clues? Thanks for the response.

[Dave at Pelican Parts]

No good way to know from that photo if the timing is in spec or not.

The original timing mark is on the other side of the fan, closest to the engine. You have to get a good way in to see it; the mark is obscured except when it goes past the notch.

https://www.pelicanparts.com/techarticles/914_timing/914_timing.htm

--DD

[bobswei]

Thanks for the link. I do recall setting timing but years ago. That should be a good refresh for me. Might be a bit before I get to it since we're getting a rusty '67 beetle in for some new metal, in the next day or so. Once again, the 914 goes to the back burner.
Thanks for the response.

[r_towle]

Get the car up on three wheels, one rear wheel off the ground.
Put car in fifth gear
Spin airborne wheel backwards, which spins motor forwards.

On the bottom of the engine at the transmission is a large hole, spin engine till you see the notch for TDC.
Paint it white with nail polish.

Now you will be able to see better when you set your timing.