The 242 is finally running and rolling after a complete rebuild of all major systems. I'm now beginning to sift through the list of secondary issues.

First on the list is K-Jet, which seems to have a rough and lumpy idle when cold or when warm. At higher RPM's, it runs perfectly. I can adjust the idle with the screw, but anything below 1000 RPM and the engine practically dies. It just gets very rough and lumpy, barely hanging on. At higher speeds, there is no detectable miss or roughness, and it pulls hard during the rest of the power band.

Some facts:
1. Engine is newly rebuilt.
2. Has a new and tested engine wiring harness.
3. Has gas in the tank that is about 9 months old.
4. Has confirmed spark to all 4 cylinders.
5. Has timing set to 15 deg at 1000 RPM.
6. Has a new fuel filter. Has previously replaced main and in tank fuel pumps.

K-Jet components examined so far:
1. Tested the motion and centering of the airflow sensor. Appears good.
2. Tested resistance of control pressure regulator as per K-jet.org instructions. Tested good at 23 Ohms.
3. Checked function of aux air valve. Motion is smooth and easy and it is not stuck open.
4. Removed the AC solenoid from the intake circuit to eliminate that as a possibility.
5. Frequency valve appears to be working, I can hear it while running.
6. Systematically removed other vacuum circuits while running. No changes.
7. Unplugged cold start injector while running and warm. No changes.
8. Checked connections at CIS computer in cabin. Everything was clean and in good order.

Things I still need to test:
1. Measure fuel pressure (a pain to build the rig, but I know it needs to be done).
2. Adjust fuel pressure regulator?
3. Adjust mixture?

I'm currently looking for other things I can test to better understand and fix this problem.

Cheers,
Jason