I need some help

[EPorsche]

I've come to discover that my car, an early '81SC (Dec '80 build date, requires a different lambda ecu than the later '81SC and later cars. My car requires the Bosch unit ending in 055 and the later cars, at least April 1981 and later, require the 037 unit. So I was thinking that the 12 pin connector that sits on the cross member between the rear shocks might be wired different.

Could someone with an early car tell me what wire goes to what pin on that connector. Only 7 of the 12 pins are used.

Thanks

[boyt911sc]

EPorsche,

Does your engine have the following:
Temperature switch (35°C/95°F)
Throttle switch (15°)
Cold acceleration control unit?

Above items are the items added after '80 SC. Have you been using ECU (-055) for your engine? If you have any of the above items, ECU-055 is not the correct ECU for your engine.

Have you been running this '81 engine using the '80 ECU? Keep us posted.

Tony

[EPorsche]

I do have all the above items. There was a change early to mid year with the 81SC that switched from the 055 to the 037 ecu's. The way you can tell which one is right for your car is by looking at the lambda ecu connector. If your connector have female pins on both rows, then you need the 037 ecu. If like my car, which I picked a short time ago, then you have female pins on the top row only and require the 055 ecu.

[Pazuzu]

I know that the early 02 cars have only 6 connections there. My Feb 1980 build SC has only 6. I do not know when they switched to 12 pins.

[boyt911sc]

Originally Posted by EPorsche

I've come to discover that my car, an early '81SC (Dec '80 build date, requires a different lambda ecu than the later '81SC and later cars. My car requires the Bosch unit ending in 055 and the later cars, at least April 1981 and later, require the 037 unit. So I was thinking that the 12 pin connector that sits on the cross member between the rear shocks might be wired different.

Could someone with an early car tell me what wire goes to what pin on that connector. Only 7 of the 12 pins are used.

Thanks

EPorsche,

If I understood your post correctly, you have an '81SC engine (US model) with 12-pin connector (OXS plug harness), and using ECU-055? Someone gave me an ECU for '82 SC (?) and its marked as -055. So I'm interested to find out if the ECU-055 could make late SC engines ('81-'83) run.

The 6-pin connector ('80) and the 12-pin connector ('81-'83) have totally different wire orientation or connection. I'll go over my notes and post the difference. PM sent Thanks.

Tony

[EPorsche]

boyt911sc,
My newly acquired car had the 037 ecu and ran, but did it in open loop. Trying to set the dwell was impossible. There was no control of the frequency valve. The way to tell if an 055 will work in '81 1/2 and later cars would be to look at the ecu connector. If the connector only has female pins in the top row and none in the lower row then you would have to use the 055. If you have female pins on both rows then I think you have to use the 037 or 006 ecu's.
Here is the 006 and 037: The 006 is upside down





Here is the 055: Note some pins are not used on top row

[boyt911sc]

EPorsche,

I'm having a problem following the logic of your decision to use a -055 ECU for your '81 SC. You are correct in stating the difference between the ECU's for '80 and '81-'83 SC engines. But have you considered swaping/installing a good ECU-037 in the car?



And how would you make the CACU (cold accelaration control unit or enrichment unit) using an ECU-055 to work? Looking at the wiring diagrams, it might be feasible to use an ECU-055 with some modification or re-configuration of the wiring connections. But, why go into this trouble when you could simply install a good working ECU-037 or -006 instead?

This is an interesting concept. Please help us understand your choice. And keep us posted. Thanks.

Tony

[SCadaddle]

I'll add that my USA 82SC (build date 6/81 edit 07/81 not 06/81) runs with the -055 box. Somewhere along the line the previous owner(s) connected something wrong and absolutely fried i.e. melted the wiring to the Frequency Valve. When I bought the car the FV was inoperable, the O2 sensor was disconnected and the CIS tuned way rich for it to run.
Sorted out the burned wires, replaced the O2 sensor and connected it up, FV came to life and CIS was tuned to run in closed loop mode. Life is good. 3 months later all of a sudden the car went very lean.

Tony et al helped me diagnose the O2 relay.....

Turned out to be the 055 box not outputting a signal to the FV.

Sourced a used box from the classifieds. Had a well known 911 mechanic swap it into his known, well running 83SC. Ran like ***** with no FV action. Of course it did the same thing in my car. So it was a dud. Sourced yet another 055 box, tried it in the 83 and it ran fine. So we put it in my 82 and it also ran fine.

[EPorsche]

Tony,
I had a good 037 ecu in the car (checked by ecu doctors). I also swapped out the oxygen relay. The FV still didn't work. That's when we notice the difference in the ecu connectors. Now, I might be wrong, but my understanding was that the switch to the 037 ecu happened mid year of '81.

Did the 12 pin wiring change any from 81 to 83?

I'm not an expert and will take all the help I can get.

Thanks

[EPorsche]

Tony and/or SCadaddle,
Could you guys take a picture and post it of the connector to your ecu where it shows the female pins?

[SCadaddle]

This is the wiring diagram we used on my car and I want to say the wiring to the FV was via pin 15 of the ECU. It's a red/black wire; there are 2 red/black wires that actually go to the FV that make the FV part of the circuit. As for photos of the connector I'm a bit hesitant to disconnect things as right now it is working. Lets see what Tony comes up with first.

[Bob Kontak]

Here is an excerpt from the CIS primer.

It shows the 055 for 82 / 83

037 for 81

006 for 80

My head is starting to hurt

[Bob Kontak]

I have spoken with EPorsche twice and I am pretty sure he has a firm grasp on the issue.

I am going to run the data discussed up the flag pole and let folks shoot it down if not correct. Simply an academic exercise.

The 80 box is an 006. It does not have WOT enrichment. It has many more male pins than used per the electrical diagrams - two rows of pins.

The 81 (part year) is an 037 box and it has many more pins than used and has two rows.

81 part year and 82-83 and later years for the 930 use the 055 box. It has one row of pins and every pin is used.

The 037 and 055 boxes are interchangeable. The wiring harnesses are interchangeable (all 81-83 cars) EPorsche has no female connectors on his bottom harness row clip on connector on his 81 but I do on my 81 - I have the 037 box.