Beyond resistance, how can you check a frequency valve in a non-running car?

per peter Zimmerman

Peter Zimmermann's Avatar


1. Raise engine lid,
2. Loosen two rubber straps for the air filter cover, and lift off the filter,
3. Turn on ignition, do not crank/start engine,
4. Reach into the open air box, locate the bend of the sensor plate arm (a curved metal piece that is the only obvious, easy to see, component inside the plastic air box). Lift that arm, gently, about an 1/8" to a 1/4", and then quickly release it (its possible to flood the engine doing this so be quick!). While the arm was raised did you hear the FV buzz?

...yes. The freq valve system is functional.
...no. The freq valve system must be diagnosed.

Post what you find. BTW; the symptom for a faulty/not functional freq valve is hard cold starting, and very bad running for the first five or six minutes following a cold start - unless someone has tried to put a bandage on cancer and set up the fuel mixture to work without the valve (very bad technique).
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Pete Z.
Last edited by Peter Zimmermann; 11-01-2011 at 01:14 PM..

Just another quick thought. Maybe that loose connecter goes to the frequency valve or maybe the connections got mixed up. It's been awhile since a looked at mine but the connectors are probably the same.

Here is a picture of the electrical connectors from an 1982 schttp://forums.pelicanparts.com/uploa...1597773737.jpg

The three electrical connectors are both two pin - the air flow safety valve on left, the FV right upper, and the cold start valve. On my car (engine '82 SC) two of these three connectors are the same color! As you can see, the wires are long enough so all or most could be plugged in to any of the gizmos.

Maybe it is because of my hearing, and perhps because I don't have the heater blower, but I test the FV when lifting the metering plate by putting my fingers on the FV to feel it vibrating.

The fuse for the interior lights is the fuse for the electronics!

You can disconnect your 02 sesnsor and the frequency valve will not operate. The car will run with it disconnected.

I would take a look at your injectors output. Meaning, there is a procedure to get you close. take out the injectors and put them in jars, bypass the fuel pump relay and power the fuel system. You should then adjust your metering plate with the 3mm screw on the left of the fuel distributor. Turn it until fuel just starts to eject and then turn counter clockwise 1/2 turn -reinstall injectors and start it up. There is a screenshot I captured somewhere from the factory manual that covers this.

Thanks folks. To make certain I hadn't hooked up anything wrong I pulled the motor last week. I have always worried about those two blue plugs, but I labelled them when I pulled the harness off and sure enough continuity and other tests showed that they were hooked up right. Cold start is hooked to thermo time switch etc. Will test the frequency valve, but I am pretty sure it buzzes as it is supposed to. Will be following up on fuel pump delivery and pressure today or tomorrow.

Travis - the FV will run with a disconnected O2 sensor. That's what the default duty cycles in the "ECU" are for. No working sensor, no adjustment of the AFR while driving. But the FV will cycle.

I learned something new!

Metering plate adjustment........
 

Travis,

Adjusting the 3-mm set screw will not alter or change the position of the metering plate as you suggested. What it does is raise or lower the rest position of the fuel distributor’s plunger. And because of this change in elevation, the fuel mixture is directly affected. But the metering plate remained unchanged.

Tony

I should have said that it will adjust the idle mixture and kept it simple. Anyways I get the impression that the car is stalling from being too rich.

ok ..i did not see this here yet.Worn,disconnect the emergency fuel pump shut off(sensor plate bosh plug).When you put the key on (with this sensor disconnected) do you hear the fuel pump-with the key in on position?Let`s start here.....report after .....
Ivan

Current status..........
 

Warren,

Any update regarding your newly rebuilt motor? It has been a while since we last heard from you. The weather is slowly getting colder and it would be winter soon. Try to get the motor running before putting the car in storage. Keep us posted with your progress. Thanks.

Tony