So my frequency valve is not working

[Bob Kontak]

Cool. When on ohms what does it read when you touch the black and red leads together?

[911 sc]

It reads 0

[Bob Kontak]

Great. That is what it should read when you connect the "other" connector, via the multi meter to the engine case.

You do have the connector split open though.

The broken connector is the power line to the fv. The intact #1 connector is the link from the fv to the Lambda box.

Bottom line on the ohms testing is that you take a piece of wire and touch the black probe to one end and the red to the other and the MM senses the degree of difficulty it is to get through the line. Real easy, like a nice fat wire that is clean as a whistle, no problem, zero ohms resistance shown. A broken connection in the wire will read the number 1 on mine meaning infinite resistance. Nothing is getting through.

Take a lead pencil and rough out a line on a piece of paper. Heavy pencil. Take the probes and touch the pencil line one inch apart with the probe. It will give you a resistance reading. That shows SOME resistance.

I think you have something that is not talking to something via the wires. Lambda box could be toast but you do not want to buy a box if you do not confirm that it is the box.

You need to test the connections.

[911 sc]

Do u want me to test the 12 pin connections with the jumper in or relay

[911 sc]

Ok checked them all none registered on the ohms all were 0 . If i did it correctly

[Bob Kontak]

When testing continuity, no power is fine. The multi-meter does not know the difference.

It is just sniffing to see if there is a path.

[tkmoore]

You probably already checked this, but could your interior light fuse have blown? Believe it's fuse 18. Interior lights, lambda and FV system all use same circuit and run through that fuse. If it blows, FV may not work. Just a possible simple solution. Tim

[911 sc]

Yes fuse 18 is good thanks for the idea

[SCadaddle]

Just a heads up if you decide to replace that 12 pin connector "block". I've recently witnessed a factory trained Porsche mechanic/guru break 2 of them in succession trying to put the plastic cover piece over the plastic part the wires are inserted into. They are extremely brittle and they are supposedly $50 each. Somebody here on the forum I noticed is casting their own part and I'd look him up.

As for the wiring between the Lambda box and the FV, mine in the engine compartment was melted due to a short by a previous owner, so I bypassed the factory wiring with a pair of wires spliced in to the Lamda box/O2 relay area and ran them through the grommet in the rear of the bulkhead at the tunnel and up to the FV problem solved. If I didn't have to take the seat out I'd share how mine is spliced in, however, it should be easy for someone with the wiring diagram. Good Luck!

Here you go, post #19, Timmy2 makes that connector.

http://forums.pelicanparts.com/porsche-911-technical-forum/834525-83-sc-backfires-wont-run-help-please.html

[911 sc]

Thanks for the tip Scad

[911 sc]

I think this possibility may be my problem a bad ecu .

What do u guys think ?

[911 sc]

Other questionable solder joints

Also front of board locations

[911 sc]

[Bob Kontak]

I have fixed a couple of circuit boards solder joints. It was fairly evident wearing reading glasses where the solder joints were cracked, though.

The way I could really tell was taking a high megapixel photo an blowing it up.

A continuity test can maybe isolate a break. Ohms setting. One probe on the pin and another on the base of the surround solder. Should read zero. This test is not foolproof though, I don't believe. Once stuff heats up, gremlins can rear their heads.

[T77911S]

take a look for cracks. if you dont see any, hit the ones with solder that look questionable.
clean the flux off the board too.

[911 sc]

Its was a bad ecu
thank you everyone for your help
tkmoore thanks for the ecu!

Bob Kontak you go over and beyond on this forum to help everyone so a big thank you to you!