I think I'm on to somthing here, (many of you may be suffering this too!)
Typical EFI problems, Stall when start, poor fuel economy, irratic idle, ect, ect, but no codes. "pass 11, My As*!

Using a breakout box I found Power to the EEC-VI to be 15.43V, Keep alive Power 15.4 and EEC-IV power relay loss at 0.02V

On the ground side, Main power ground KOEO 0.02, Signal grounds to be 0.01 and all other grounds to be 0.01V.
Power in and out on EEC-IV all good.

BUT the Reference Voltage, (power to the sensors) is extremley high, 6.55V. The spec is 4.9 to 5.1 Volts.

Now most of the sensors measure higher then spec. voltage too.
So if the range is off for all the sensors, the inputs to the EEC-IV are incorrect sending the computer to adjust for things that just ain't happning.
For example the coolant temp is telling the brain the temp is 40 degrees when it's 80. the ACT is saying the air 40 too. The bypass should read 9.5V to 10.5V, but at the breakout box I get 15.2V, (pushing more air than needed,= stall)
All this bad inputs to the computer, No wonder its stalling and running like poo.

My question is how do I get the Power to the sensors down to the range of 4.9 to 5.1V?

I'm thinking if the feed voltage comes down, the sensors will react favorably and calm the computer down. Thoughts?
Reamer

 

Sounds like the internal voltage regulator for the Reference Voltage is bad. You might be able to wire in an external 5.0 or 5.1 Volt Zener diode. I'd guess at least a 1 watt Zener (more watts if available). Anode to ground, cathode to Reference Voltage line. Radio Shack or other electronic supply stores should have Zeners in stock. If that doesn't work you'll likely have to spring for a new module.

 

Actually the cathode (stripe end of Zener diode) should connect to the Orange/White (O/W) Reference Voltage wire and the anode should connect to the Black/White (B/W) Reference Return line. I'm not completely sure the B/W wire is tied directly to ground. But first, measure your Reference Voltage (at one of the sensor connectors) between the O/W wire and the B/W wire; that's where it should be the true Reference Voltage.

 

Measuring this, O/W to B/W = 6.55 V Do ya think this is driving the system crazy?

 

Just a question because I don't understand, how does the EEC get 15.4v, when the nominal voltage for a 12v lead-acid battery is 13.6?

 

Reamer,
Could be having some effect, its about a 28% increase in reference voltage. I'd try the Zener. If I remember correctly they are only about $1.50.

 

check alt output as sugjested by leadhead
max should be about 14.2

 

Yes, I would check the charging voltage too. Or it might be ok and your meter is a little off? That would explain why the computer voltage seems high.

If the computer gives you an 11, then that means it's happy. Your stalling when starting and erratic idle sounds like the throttle body and IAC motor are clogged with soot and carbon. A very common problem.