Car running like crap, 4 days before Hershey Options

[saigon71]

Could use some "check this" help:

Running a 2056 D-jet.

Over the winter I adjusted the valves and changed the oil. It didn't need much else.

This Spring, I installed a new distributor cap and new set of points. Adjusted dwell to 50 degrees before setting timing dead on at 27 degrees BTDC.

The car was running awesome. (IMG:style_emoticons/default/driving.gif)

All of the sudden, the car has developed a pretty serious intermittent miss. There have been times it runs flawless on a test drive, only to start sputtering the next drive. When the sputtering and bucking occurs, there is sometimes an audible "pop" or "knock" sound coming from the engine bay.

I've got a new FI wiring harness from Jeff Bowlsby installed.

So far I have done the following:

-Check fuel lines for kinks
-Added "Star-Tron" enzyme fuel treatment to fuel stored in tank for winter, have since added two tanks of fresh gas
-Fuel steady pressure at 31PSI (but I couldn't get the car to act up when I had the gauge attached)
-Verified point gap hadn't changed after setting dwell
-Verify that CHT is tight (CHT is almost new)
-Cleaned & adjusted trigger points
-Unplugged TPS - it did not make a difference
-Checked FI harness grounds at the back of the engine
-Pulled all 4 spark plugs to check for fouling - they all looked good
-Swapped the coil with a known good one

Any advice on other things to check would be appreciated.

[Spoke]

Where are you measuring the 13.6V and 12.5V when running? At what RPM are you at? If 12.5V is at the battery, you have an issue. Also what is the voltage at the coil?

With the engine running at high idle like 2k, measure all 3 pins of the VR with respect to chassis ground. Not the engine but the chassis. D+ should be 13.5V, DF should be 6-10V and D- should be less than 0.5V. All voltages DC. Don't disconnect anything; just jam the DMM probe into the connector to the VR.

[saigon71]

Where are you measuring the 13.6V and 12.5V when running? At what RPM are you at? If 12.5V is at the battery, you have an issue. Also what is the voltage at the coil?

With the engine running at high idle like 2k, measure all 3 pins of the VR with respect to chassis ground. Not the engine but the chassis. D+ should be 13.5V, DF should be 6-10V and D- should be less than 0.5V. All voltages DC. Don't disconnect anything; just jam the DMM probe into the connector to the VR.

13.6 running without lights on, 12.5 running with the lights on. Both measurements taken at the battery, car idling at 1100 rpm or so.

I'll run your other tests tomorrow after work.

[Spoke]

Where are you measuring the 13.6V and 12.5V when running? At what RPM are you at? If 12.5V is at the battery, you have an issue. Also what is the voltage at the coil?

With the engine running at high idle like 2k, measure all 3 pins of the VR with respect to chassis ground. Not the engine but the chassis. D+ should be 13.5V, DF should be 6-10V and D- should be less than 0.5V. All voltages DC. Don't disconnect anything; just jam the DMM probe into the connector to the VR.

13.6 running without lights on, 12.5 running with the lights on. Both measurements taken at the battery, car idling at 1100 rpm or so.

I'll run your other tests tomorrow after work.

Does the battery voltage come up w/lights on as RPMs rise?