So my frequency valve is not working

[911 sc]

1982 911

What to check for first?

What causes the frequency valve to not kick on other than the oxygen sensor relay?

I have a new relay on order from our host but it will not arive until next week I was wondering what else I can check.
thank you

[T77911S]

fuse 18

[911 sc]

Ok checked fuse 18 still nothing

[911 sc]

Anyone

[Dave Kost]

it could be the ECU too. I just went thru this with my newly acquired 83.. Both the ECU and relay wasn't working. Chances are that it is the relay only.

[gazzerr]

Could be the oxygen sensor itself. The FV might be actually working but the duty cycle is so low you can't hear it. I'd check that the sensor is actually plugged in and working. My FV was not audible until I changed out the old oxygen sensor, then I could hear the FV working away.

[Bob Kontak]

There is a way you can cheat the system and test freq valve with key off. You have to jumper the relay ports with a wire. Let me find the correct post and will link it in an edit in this post.

Here is the link. See post 13. I was on the phone with the original poster of this thread when he got it working using this method. Let me pull the test on my car right now so you don't screw something up based on my recommendation.

http://forums.pelicanparts.com/porsche-911-technical-forum/559200-911-sc-running-flat-no-idle.html

[911 sc]

Dave i tryed calling you but your phone was off. Give me a call at your convenience thanks

[911 sc]

Yea im thinking it may be my ecu because my old relay is clicking but fv still not running.

Could the relay be bad but still click when i plug it into the running car??

By the way symptoms are rough idel backfires will not rev up spits and sputters.
thanks

[Dave Kost]

it could be the ECU too. I just went thru this with my newly acquired 83.. Both the ECU and relay wasn't working. Chances are that it is the relay only.

[Dave Kost]

i sent you a pm. i am away until july 14th.

[Bob Kontak]

Originally Posted by 911 sc

Yea im thinking it may be my ecu because my old relay is clicking but fv still not running.

You can't be sure right now. You can have a perfect relay and a perfect ECU and the 12 pin connector by the driver's rear shock could have a corroded connector not allowing voltage to your freq valve.

Can click all day.

Still working on confirming this mentioned test for you.

These are your symptoms, correct? I pull the relay at 23 seconds in.

[911 sc]

Yes my syptoms, however my car may be backfiring more as soon as i touch the throttle

[Bob Kontak]

I had the cover on the air intake and the camera does not really pick up the "pop' very well.

Confirmed test. Taking some pics so you can perform if you choose.

[911 sc]

Ok thanks bob much appreciated and ill check the 12 pin connector too

[Bob Kontak]

The top two middle connectors are the two 87's. The bottom middle is the 30.

Flankers are not necessary for test.

Wire the base of these three prongs together (A PITA) and plug in.

Preferably if you can use a wire like I crafted and plug them into the corresponding female ports on the wire loom that will send 12V to the freq valve.

You cannot hear it run when under the passenger seat. You can hear it run through the engine grill.

Good luck. Worked for me just now.

If nothing, then more digging.

[Bob Kontak]

Originally Posted by 911 sc

Ok thanks bob much appreciated and ill check the 12 pin connector too

Don't do that now as it is pain (the connector itself). Your relay may just be tired or cooked.

This will absolutely confirm that juice is or is not getting to the freq valve. If it confirms, screw the extra work.

Well, it can confirm that freq valve is toast but that is VERY rare.

[tkmoore]

If you end up needing an ECU let me know. I've got one avail for 80-83 sc cars. I bought it from a pelican recently to help diagnose if mine was bad and it turned out to be an entirely different problem so now ive got a spare ECU. Tim

[911 sc]

Ok just so im understanding correctly wrap the three said prongs together and run three wires to the corsponding female ports and this should kick on the fv while key is on?

[911 sc]

Thanks tkmoore ill keep you posted