Frequency Valve and Lambda computer testing. Please Help.

[bit]

Hi Guys,

I have a 1980SC which has strarted to run like a bag of poop. One moment it was fine, and then all of a sudden it appered to have lost about 50% of its' power, and started to backfire/sputter. I temporarily manually richened it up the mixture and it is somewhat drivable (barely). From doing some looking around, I noticed that the frequency valve is not making its' buzzing/vibrating noise it always used to make. The Haynes manual sez to test the fv and measure 2 to 3 ohms, mine measures 4.3 Ohms. I checked the relay under the seat beside the lambda unit, and verified the relay is ok (applied power to the coil and measured that the outlined points made contact). I checked that the connector on the fv is getting about 12v. It appears that the lambda unit is getting power too from the connector. My question is, could by lambda unit be bad? How can I test it? Does the 4.3 Ohm measured value indicate that my fv is pooched?

Please help if you can.

.Steven
1980 911SC

[konish]

Steven,
If you show any resitance at all in the vlave winding then it should be fine, although a higher resistance may suggest that some corrosion has occured on the coils increasing the resistance(?) If you removed the relay to test it, then you may not have tracked down the cource of your power supply. Does your car's interior lights still work? If not, replace the fuse becasue it provides power to the solenoid.

R/
Dustin

[konish]

okay that was a horrible reply, let me try again...your power source problems may be the fuse for your interior lights. That particular circuit provides power to the lambda solenoid, which in turn provides power to your freq valve....

R/
Dustin

[john walker's workshop]

....to the lambda relay, which powers the computer, which works the frequency valve, which makes the engine run right. the relay is the usual culprit. warm the engine and at idle, unplug the relay and see if the idle gets funky, or no change. it has to get funky, unless it's there already. like konish says, check the fuse first. the relay is under the front of the passenger seat, toward the tunnel.

[konish]

dangit! I meant Lambda RELAY not SOLENOID...like JW said. Please don't go crazy looking for a Lambda solenoid (sorry, long, dry day at work)

[bit]

Hi guys,

Thanks so much for the responses. I spent about 5 hours tinkering about and after basically testing everything I could and tracing wires and whatever, I removed the lambda controller from under the passenger seat and opened it up. I traced the voltage coming in on pins 8 and 15 on the main circuit board. Very quickly, and found that ONE solder connection on the main power transistor was bad (cold). I resoldered the connector (and soldered in a jumper wire so it won't happen again) and right away, my frequency valve started making the wonderful music is used to make. Car is running so strong again, I had to lean my settings out and left the O2 sensor disconnected. It's amzing the power loss with the Lambda subsystem shuts down. And really there is no way to bypass it, unless you get a 78-79 fuel distributor which doesn't need or use lambda, so I'm told.

Another funny observation is the more I tried to fix the frequency valve problem, the more I questioned whether there was any sound coming from it before or not. Once I heard it again, I knew right away that it was fixed.

Take care,

.Steven
1980 911SC