Idle adjustment question, Idles high or slowly stalls Options

[BillC]

I have an idle adjustment question for all you D-Jet gurus:

I can adjust the idle air screw on the throttle body so the car idles at 1600 RPM, and it will happily idle at 1600 all day long. If I turn in the screw just a little bit, like 1/4 turn, the car will slowly drop idle speed down slower and slower until it stalls. I can blip the throttle to keep it running, but it just wants to slow down and stall. This is all when the car is fully warmed up.

How do I get the car to idle steady around 1000-1200 RPM? 1600 is just too high.

Car is a '73 2.0 with factory D-Jet. I installed new Standard Products FJ67 injectors, and the fuel pressure is 29 psi. There are no leaks in the intake side, and the idle adjustment screw is about 2 turns out (so there's plenty of adjustment available in both directions). The MPS hasn't been messed with, and the ECU looks like the correct unit. All new vacuum lines, fuel lines, pump & filter, and fresh gas. New @JeffBowlsby engine and alternator wiring harnesses.

Known issues: it has the wrong CHT sensor (it's the one that's commonly available) and I think the TPS board has worn traces. I finally found the right CHT and ballast resistor, and I also have a 914Rubber replacement TPS board, and I will install both of them when I get a chance. However, I don't think either of those should keep it from idling at a reasonable RPM.

[Superhawk996]

I’m sorry that you’re still struggling with this months later after throttle body swap, etc.

If I were you, I’d be going back and questioning all my assumptions.

As I re-read this thread there are lots of assumptions being made about fuel mixture (no photos of plugs - are they rich or lean?).

There appears to be a new reference to timing being as much as 25 degrees at idle? Have you verified the orientation of the dizzy drive? There are 12 teeth on the dizzy drive - each amounting to 30 degrees of advance or retard depending on how it’s installed.

Likewise - as the vehicle is spiraling toward stalling have you tired zapping it with starting fluid and what happens? Has it been confirmed that when the engine is hot that the valves still have some clearance and valves aren’t being held open forcing the loss of vacuum at low rpms? Even silly things like making sure the coil has a solid 12v even as the vehicle is losing vacuum and trending towards stalling.

These things really shouldn’t be in question. Perhaps I’m just not caught up or missing details or things that weren’t documented here?

If all else checked out after re-verification of assumptions I might even pull the oil pump just to see if I could see any ID on the camshaft nose (not all do).

Again so sorry that we haven’t helped you get this resolved by now. I wish I had the magic answer in my pocket but simply don’t have enough info at this point. It’s gotta be very frustrating I’m sure. Keep goin, be data driven, and logical in the methodology (as you have been) and eventually this will get solved.