MFI Tuning Question

[lwa]

I previously had the CO set to about 3.8% both idle and part load. The car ran pretty well, but would not idle at less than 1400 RPM. The bypass screws were all the way in and the stops backed out. I figured the throttle bodies required a rebuild.

This winter I started again working through CMA. In that process I found the distributor advance short about 10 degrees and had that rebuilt. With the advance mechanism working, the idle RPM dropped to about 1200.

About 2 1/2 months ago, I pulled the throttle bodies from the car. I found quite a bit of daylight when they were "closed" and those too went out for a rebuild.

They are now back on the car, the linkages are set, and I am attempting to reset the mix. I have 114 mm from the pump to the cross bar. The linkages to the TBs are set without preload.

I am measuring the exhaust using one of these analyzers: http://bridgeanalyzers.com/9005_Brochure.php4. Its something I can borrow. The analyzer runs off battery. I can place the probe up the exhaust, tape the hose to the side of the car and drive around while making measurements. To set part load, I drive at about 2400 RPM in 2nd gear dragging the brake a bit. I have to keep it steady for about 15 seconds, while the analyzer reaches steady state. Following that technique, the results are repeatable.

Right now, the part load CO measures about 2%, which I know is low.

However, the idle exhibits a very curious behavior. I start it up and let it warm up, the car warms up and the idle settles at about 1k RPM. The CO measures about 0.25%, which I understand is very low. If I hit the throttle, the RPMs rise to about 2200 and the CO now measures about 5%. It stays there. I recheck the linkages and everything is still on its stops. If I turn off the engine and restart, it again reverts to 1k rpm. If I bump the throttle, things revert to 2200 RPM.

At this point I've disconnected the cold start injector and the overrun solinoid.

Is there something wrong with the pump, or should I just keep working on the part load until that is right?

Larry
'71E Targa