Hey guys, im trying to figure out what the issue is now, just when I almost had it running right!
So long story short, My Frequency Valve is now cutting out.
(couple notes: I have a Wideband O2, and a Dual adjustable WUR, and the Regular O2 replaced only a few hundred miles ago.)

My accumulator is leaky (and maybe a couple injectors too??) So i have a switch to turn on and prime the fuel system. I connected it at the FP relay. When I turn that switch on (car cold/not running) The FV also runs. for a few seconds.

Now when i start the car, I can hear the FV running at first. Seems like when the car starts to warm up, it starts cutting out, and then stops completely.

If I turn the car off and then turn on the Fuel Pump, I hear the FV run for a split second. So i don't think its a wiring issue.


(Possible red herring): So I have been messing with the WUR and the mixture screw on the Fuel Meter, trying to tune it, as some point it was OK, not great, but good enough to drive. But recently while trying to tune it I discovered a leak in a Vac Line.
Now, I remember at one point a while back, if I was messing with the WUR, while trying to set pressures, at a certain adjustment (moving the dowel pin up and down) the FV would cut out. (but that is without the engine running). Could I have adjusted the WUR that far out of range to cut out the FV? (and yet still have the engine run?) Last couple times i drove it, when the FV cut out it went really lean, and I had to counter that by enriching the mixture on the Fuel meter, and then when I got back home, I think the FV came back on, as when I parked the A/F was 9.

 

anyone?
or is there a better forum for CIS issues?

 

Beside the couple of issues your CIS is suffering from as you write above, ....

Check for proper voltages at the ECU wiring (port 15) and the frequency valve (Port 8) and also check their Ports 87 and 87b at the OXs Relay if a continous current flow is present all time.
See attached diagram

 

yes. pelican parts forums have some of the best technical people in the world for CIS cars.

 

You may have an intermittent Lambda ECU (under the passenger seat) problem. Check pin 8 of the ECU, and the FV, for a constant 12V with the engine running.
Check here; https://www.systemsc.com/products.htm

 

can you comment on what the root cause might be? such as failed solder joint, or circuit board component?

 

That's it!

 

Ok well I just did a simple test (previously I was driving and had to make adjustments to get back home). I started the car, and it started ok, FV was running, Put a multimeter to the wires at the FV it was at about 11.8-9v the A/F was about 12.5. Let the car warm up and idle. and after about 5-6min, then all of a sudden the A/F drops to 9.8+/- and is barely idling. I go a check and still hear the FV running but a little less intense, put the meter to it again and it now reads 11.3v.

What do you think?

PS. Can I wire in and LED to the FV to see if its on or not?

 

Once the engine is warm:

1. Pin 7 (oil temp switch) of the ECU should be at a voltage greater than 5V.
2. With O2 sensor (pin 2) disconnected, the DC (duty cycle of the FV) should be at 50%. Use a DC measurement from a voltmeter to check it or an oscilloscope.
3. Make sure the throttle switch & accelerator relay are disconnected.
4. The only inputs to the ECU that should affect the DC are;
a. the oil temp switch to pin 7
b. the O2 sensor at pin 2
c. the throttle switch & the accelerator relay inputs to pins 12 & 14.

Get the engine to run properly & repeatable with none of the inputs of number 4. above to eliminate the ECU being intermittent.

 

Ok ill try that, what is the best way to test (and is there a pin out I can follow?) the pins? (assuming I have to keep it connected.)

Im sort of getting the feeling it has something to do with temperature. (but maybe not engine temp, perhaps when the ecu heats up?) Does the lambda do Open/closed loop? just trying to think of all the things the change after the engine "warms up"

 

Monitor the FV signal on pin 15.

Without the O2 connected, the Lambda ECU is open-loop at 50% duty cycle. Temperature (oil - pin 7) is just a switch and not a sensor.

 

is there a schematic of the pins/board I can view?

 

None available.

 

Do you mean the connections/terminals at the ECU? Just check the pdf I attached above.

 

Wasn't able to test anything yet, But I was able to borrow a Lambda Box, so i plugged it in.....and Same result..... BUT I thought this was interesting: So, as before car starts normally, (A/F between 12-13 then after it warms up for a few minutes, FV stops and A/F goes to 9.8. and the engine is barely running. Then I unplug the second lambda box (while running) and the engine goes back to running better! A/F back to 12-13. Seems like a Clue?