1982---911SC Targa CIS,frequency Valve chech

[vizail]

Correct me if I'm wrong.
I I took the ECU Connector slide cover out and I found that #8 conector is Brown(negative) #14 Green/Black # 15Black /red and #16 Brown Again. Wish one if this is the one that delivers power to the ECU. As I see it the relay provide a constant + positive via 87B and the #14 Provides the negative fluctuations. Can someone corect me if I'm wrong?

Vic

[john walker's workshop]

the oxygen sensor computer is at the top. ground is at the bottom. but may be out of the picture.

[vizail]

JW
Thanks Again
Check your Email
Vic

[john walker's workshop]

that's from the factory manual, not bentley.

[Gunter]

Vic: When you energized the OXS relay, did the 12V coming from 87 & 87B end up going to the respective terminals? In other words, do you have 12V at the Frequency Valve from 87B and also 12V at the ECU from 87? Look at the electrical schematic Bentley page 970-8. Do you see how the ECU is connected and powered? Your '82 has a few more connections and components than my '80. Check all the connections from all the components; for some reason your ECU is not modulating the Frequency Valve. I disconnected the OX Sensor from the CAT Converter without any problems. Do you still have a CAT?

[vizail]

Gunter:
Today I visit a fellow Prsche Owner and let me use a VW Jetta Frequency Valve to see if I get some voltage to the FV terminal from the relay and ECU. I first tested the Jetta FV by applying low Voltage 4, 5.5V upto 9.5v . from then on up to 12.v I clearly hear the valve open and closed every time I connect and disconnect the wire. Then I proceed to intall it to the FV connector in my Targa.
I start the car and let it run for while and did not get a responce from the FV conector I then disconnect the cables from the remote FV and put my Voltage counter and, no Voltage or voltage pulsation where coming from the Connector. I hotwire tested the remote FV to see if it operates. It did..!
The conclution is that I'm not getting Voltage to the FV.
He has replaced the FV on his own 911 3.2racer instaling a mechanical Valve. He has performed this alteration in other VW, AUDIs and Porsches. He is making me one. I,m going to take a picture and will try to post it.
Let me tell you that his Posche is a T Class 3.2 and is working perfectly.

To anwer your question. 87 and 87b are getting Juice but for some reason the computer is not producing a pulsation and the engine runs rich all the time.
I'm also thinking about a centrifugal Ignition distributor for my 3.Litter Targa. Do you Know where I can find one? I'll keep you updated.

Cordially

Vic

[john walker's workshop]

voltage to the FV comes from the relay, not the computer. you previously said that the relay terminals 87 and 87b got 12V when the relay was activated. if you have 12V at the 87b relay terminal and none at the FV, there's an interruption in the wire. the only junction between relay and FV is the 12 pin connector in the engine compartment. black/red wire. (relay, thru connector to FV, back thru connector to computer).

[Lorenfb]

This thread has become too complex!

It's VERY simple to checkout the Lambda control unit on a 911SC:

1. It must have a ground on pins 5 & 16 on the 35 pin Lambda connector.
2. It must have +12 volts on pins 8 & 15 (freg valve), (key on).
3. If you ground pin 15 with the engine running, it goes rich and idles poorly (unit disconnected).
This checks the freq valve.

If the above check out, the Lambda unit is bad. If you need it tested/rebuilt, send it to Pelican.
If they don't, use the diagram on this thread for wiring/relay troubleshooting.

That's it. It's that simple. Let's not make it a life time project!

For more info check out this web site (www.systemsc.com) on the Diagnostics page.

[Gunter]

Loren: I see only 11 connections (Pins?) on the schematic in the Bentley manual. You mention 35? Please, explain.
I see 5 & 16 as ground
I see 15 twice: 12V from FV (Blk/Red) and 12V from the relay (Blk/Wht)
I don't see any pin 8?
If you ground one of the pins 15, you'll get a nasty short, no?
What about all the other pins 2,4,6,7,12,14,17 on the ECU?
Could you be more specific? Please.

[Lorenfb]

"You mention 35? Please, explain."

Most are not used. The connector is still a 35 pin connector.

John provided an excellent diagram which has all the info needed.
Pin 8 is shown on the diagram going to the Lambda unit to supply it power.
Pin 15 is the variable duty cycle grounding pin to the freq valve.

1. pin 15 open - lean
2. pin 15 ground - rich
3. pin 15 @ 50% duty cycle (6-7 volts D.C. average) - normal with no O2 connected.

"What about all the other pins 2,4,6,7,12,14,17 on the ECU?"

Pin 2 - O2 sensor
Pin 6 - D/C (don't care)
Pin 7 - cold running fuel enrichment
Pin 12 - accel enrichment

Pins 14, 17 - D/C

[Gunter]

Thanks, Loren. What kind of tester is needed for the 3-prong test connection plug on the '80-'83 SC's to determine the duty cycle?
Is the OXS Control Unit and the Acceleration Control Unit on the '81-'83 one combined unit? Or are they two seperate units? Both under the pass. seat, or?

[Lorenfb]

"Is the OXS Control Unit and the Acceleration Control Unit on the '81-'83 one combined unit? Or are they two seperate units?"

Two units -

Use an o-scope or a Fluke meter that measures duty cycle.
Check out this web site (www.systemsc.com) on the Waveforms page
for additional insights about the frequency valve signal.

[vizail]

It has been a long time sice I have not reply to this forum subject, I spent some time in the hospital . My deepest apology to all you and thanks for the the camaradery.
I'll put you up to date and if you wish you can reply with your coments.

To begin with I will put some pix that will explain my findings.
Ubiously some mechanichs mess around with the wiring of this car before, as you guys can see.. In my early posts I complained that I could not get the OXS rellay to work.
I found that the Fuel pump rellay plug harness was drastically cut, and in his place they put a VW 4 clip rellay.
I change the 3 fuse carrier, Then I found that I still cant get the OXS rellay to click, somewhere the current was interrupted. I kept searchings and I found that the red/white wire that comes from the fuel pump relay to the WUR and then to the OXS rellay was cut . Then I reconnect the wire.
Suddenly the OXS rellay click but # 18 fuse burned out. I noticed that instead of a 5amp fuse there was a 25 amp . The Rellay was on and working. The clock stoped working. Then I noticed that the lugage hatch ligth, deck lid light and other intirior ligts where disabled.The # 18 fuse kept on buring
Needless to say I already have the proper rellay socket and I will change it and put the appropiate FP rellay (RED)

In regards to fuse 18 I have to keep on searching the total interior light wires because somewhere in this car is a short.
The Instruments ligths are working ok.

I kept on my search to the T12 (Firewall beside the shock absorber) connector and verify the continuity between T12 (pin1) and the FV connector and the T12(pin2) One Brown and the other Black / Red.(The wiring diagrams show BLk/Red wires but mine have one Brown and one Black/Red ) I have continnuity between one terminal at the FV connector and both (Pin1 ) and (Pin 2) at the T12, but no continuity at the other end of the FV connector
I have found that the 1981 to 1983 /911SC, FP rellay have 2 BROWN/RED , 0.5mm that receive or deliver some signal from 85 terminal to the Airflow Sensor Contact and the RPM Limiter Switch. I'm reluctant to reconnect the original FP rellay socket and rellay . I don't want to damage other components in the CIS sistem.
Cordially
Vic

[Gunter]

Vic: Hospital? Hopes for a good recovery. Man, from your pictures, it looks like some butcher was a t work at some time with your electrical. Consider new fuse blocks and carefully check the wiring, compareing all wires to a proper Porsche wiring diagram. Cheers.

[vizail]

Gunter and Friend's
Thank's for the recovery wish.

Yes... you said it right. A butcher mechanic worked in this car before.
I forgot to mention that the test performed in the T12 Connector was from the male pins (T12-1) and ( T12-2) to the FV connector with the previous reults.

Vic

[vizail]

Lorenf and Gunter

I'm still working in the electrical conections in my 1982/911SC.
I replaced the following items in the Car and wanted to share some info with you Guys hoping to get some opinion from you Guys.
I replaced the Fuel Pump harnes and installed the right Relay



Then I check almost all the wires in the Car and reconnect many wires that where disconected. One of them is the 0.75mm red/white wire from fuse 18 to WUR and Total Interior ligts.

Then the fuse #18 burned out every time I start the Car.


I test all the wires from the OXS Rellay, OXS Control Unit, Acc. Enrichment Control Unit .


Then I disconect the T12 Pole conector and the fuse did not Burn Out, The black wire at fuse #18 Total Interior lights oK.


Then with the Engine Running I performed the Following check at the T12 Pole Disconected. I took my Volt Meter and the Following readings appeared.

T12 Female Bulkhead

#1 Pin 8.8 Volts from Pin 15 OXS Control Unit/ black/ red 0.7mm
#2 Pin 9.0 Volts from Pin 5 OXS Control Unit (Brown Wire..?)
#3 Pin 13.8 Volts from OXS Cont. Unit to Pin 6 at Acc. Enrich Cont.
#4 Pin 13.9 Volts from Pin# 8 Acc.Enrichments Control to 87b OXS relay
#5 Pin 000,not in use
#6 Pin 000,not in use
#7 Pin 000,not in use
#8 Pin 000,not in use
#9 Pin 13.8 Volts from OXS Control Unit (blue/green wire)
#10 Pin 4.7 Volts from Pin #4 Acc. Enrich. Control(green/red wire)
#11 Pin 5.3 Volts from Pin #5 Acc. Enrich. Control (green/yellow
#12 Pin 000.not in use

T12 Male from the Engine While runing

#1 Pin 000 From Freq. Valve (blk/red wire)
#2 Pin 000 From Freq. Valve (brown wire ?)
#3 Pin 000 From Micro Switch(green wire)
#4 Pin 000 to 0.5 ???
#5 Pin 000
#6 Pin 000
#7 Pin 000
#8 Pin 000
#9 Pin 0.0 to 0.4 Volts from Trottle Switch blue/wht and Temp Sw 15C degrees
#10 Pin 000 from Trottle Switch (green/red wire)
#11 Pin 0.5 Volts from Temp. Switch 35C degrees
#12 Pin 000

I suspect that the wiring Harnes with the T12 Male conector is shorted somewhere or Some Components are Defective
Furthermore in my diagrams( Factory) I see that the T12-2 appears twice ..,one with the Brown wire going to the OXS Control Unit and another T12-2 with a Black/red wire, This black wire is located at Pin #4 in the Male Connector


Ok Guys I really need Your HELP here. Are this readings acceptables. Because the T 12 ,is not Connected and the OXS Control is sending some signals and No fuse burn if I leave the T12 disconected. Then Again the short is in one of the wires going to the Engine.

All the Help will be Appreciated

Cordially

Vic

[vizail]

Helooooooooooooooooo There........!

Vic

[Jim Williams]

Vic,

You asked for my personal input, so here it is. I read though the whole thread (!) and there were lots of good suggestions to locate your problem. Here are mine:

Be careful using 12v and ground to check the Freq valve. There is a current limit resistor inside the ECU i think, and if you leave the + 12 volts connected too long there is a danger you will burn out the coil in the FV.

Loren's 01-16-2005 post is not quite accurate in the way it is worded. Pin 15 will show varying duty cycles. I think that is what he intended, but it will never be either open or ground. Pin 17 is the pin you connect your duty cycle meter to.

There are 3 conditions to input to pin 2 of the ECU to check closed loop operation. 1) ground, 2) +1.5 volts from a AA cell, and 3) open circuit.

1) should result in a rich freq valve reading ~ 90%.
2) lean reading ~ 20%
3) stoichiometric mixture ("everything is OK") ~ 50%

For the complete diagram, see

<http://members.rennlist.com/jimwms/CIS/CIShome.html> Go to "lambda computers" then scroll down to the second diagram. This is a complete diagram for your ECU and how it should be wired.

The diagram indicates the normal open/closed postion of the 15 deg and 35 deg switches. That is ambient temperature. I think the acuation temperature of the thermotime switch is 45 deg C.

You need to get a long wire you can run from the ECU connector to the engine compartment, a test lead. Then check the continuity from the ECU pins to the connector in the engine compartment according to the wiring diagram, You should check each wire pin to pin for continuity and then each pin to ground to see that there are no shorts. I don't see where the voltage measurements on the open-ended connectors are meaningful, as we don't know what the readings should be when we don't know whether the wires are connected properly.

The factory diagram showing a pin 2 T12 connection at the frequency valve is in error, from my memory, this should be pin 4 T12.

HTH,

[vizail]

Jim
Thanks for the reply.

We have the Same Diagrams Ok ..,But in yours the T12-2 between the Frequency Valve and the Pin 87b OXS relay Black/ red wire that then again goes to Pin #8 Acc. Enrichment Control,Black /red wire to Pin#4, was corrected?
No Wonder I was Confused

Loren sugested that the OXS Control Unit K-Jetronics is defective. He sugested that I should have ground on Pin 5 and Pin15 from the Lambda Unit. I have a 1.5mm brown wire that goes to Pin 2 at the T12 connector and instead of ground I have 8.0 to 9.0 volts engine running. I have groun from Lambda Unit Pin 16 . I have another T12-2 in the Factory Diagrans that is a black/red wire that runs from Pin 8 Acceleration Enrich. Unit to Pin 87b OXS rellay to T12-2. This wire is located at Pin 3 -T12 Female at Bulkhead with an ouput of 13.8 Volts.
This is my Confusion..!
If you have the Originals Factory Diagrams for 1981 to 83 911SC you will see my meaning
I also perform the following test on this Brown wire from Pin 5 Lambda Connector to T12-Pin#2 .
With the 35 Pin Connector disconected from the OXS Cont. Unit, I ran a 1.0mm wire from Pin 5 at Lambda conector to Pin #2 at T12. "I found Continuity."
Every time I run the car I get Voltage in the Brown wire From Pin#5(Lambda) to Pin #2 at T12
How could this be posible if I should have Ground on this Brown wire.
I will try to Post the Diagrams.

My Friend.. be patient with me ok
I will keep in touch with you and update you

I check all the wires Connected and disconected from the Lambda Unit. I peel of the Black tubig Insulator and perform Coninuity and Voltage reading from and between segments.
O peel of the Black Insulator tubing and found that the wires were glued eithr by heat or other means. Is this Ok? I separated each one of them.



You can see the brown 1.5mm wire from Pin 5 at Lambda to Pin 2 at T12 Female


I also see the Coaxial Green OXS Sensor wire splited.. outside wires protected with black insulator to Pin #4 at Lambda Connector and the internal wire of the OXS Sensor Green wire to Pin #2 Lambda Connector

I will Give you more information on this proyect Tomorow.

Have a happy Mothers day with your wife and childrens or your Mother

Cordially

Vic

[vizail]

Jim
I'll perform the continuity Test and will Infor you

Cordially

Vic