3.6 Conversion - Euro DME O2 Sensor Wiring

[CBRacerX]

Greetings,

The 3.6 conversion in my '87 is finally coming to a boil. Engine is prepped and ready to install, and the chassis has been updated to handle the connections needed. Except one - the O2 sensor.

Some quick background - this is a 1990 3.6 with a 1997 Varioram Intake (including all engine electrics) and a US 993 Engine Harness, and Euro 993 RS DME harness and of course a Euro 993 DME. Got that?

The 993 RS Euro harness does not have a provision for an 02 Sensor, but the DME will support one if I get the connection right. There are about six connections on the DME end of the harness that are empty at this time, so one of these is "the one!" But which? I have the US wiring diagram for the DME, but that is useless in this case since the Euro DME only uses one 02 Sensor, not _four_ like the US OBD brain does.

Does anyone know:

Which pin is the single O2 sensor feed?
Where can I source the connector needed on the DME side - the dealer?

Thanks! This is the last unresolved issue electrically. I still have to connect the oil scavenge line when I get access to the bottom of the engine (exhaust is coming off for that, bummer!). But I'll be quite happy to reach that stage!

Thanks again,

Chris Brown

[CBRacerX]

Here is what a factory 993 Engine Harness Looks like "new".



BUT - I can't figure our what this connector on the DME harness is for! Any ideas??

[Bill Verburg]

Dunno, at first I thought it might be an O₂ sensor but this is what a euro M64/21 O₂ sensor will look like


Here are some other pics

[CBRacerX]

Enjoyed the "special grade 8" plugs on the vacumn line - mine looks similar

The O2 sensor pickup is helpful, now I just need the connection on the DME to make this have some more context.

Cheers,

Chris

[blue82coupe]

I believe it's the connections for the heater blower . Dan

[CBRacerX]

that isn't it. I've already identified the heater blower connections.

[Joeaksa]

Chris,

I had a pipe on my 964 engine that had been used for the oil scavenge line but it was a home-made version and the welding did not give me a warm and fuzzy feeling.

Patrick Motorsport in Phoenix had a bolt on replacement that if its not factory, it sure looks factory and works beautifully. Just put mine on yesterday and the fit was perfect. If your motor needs one you might look into this part.

JoeA

[CBRacerX]

with Patrick, so I hope that a call and an order will keep the customer service at the right level.

I am using a stock C2 exhaust to get thru inspection, so the oil line I will install is the Carrara (3.2) line to the stock connection for the thermostat.

After passing inspection, I have a set of 993 heater boxes that I am going to install, with a "custom fabbed" muffler as done by many folks on the board. For that I will use an AN to Metric adapter and connect the oil line with braided hose.

Chris

[Speedster94]

on the DME side :
lambda signal ,Green wire 0.5 Pin 28
lambda ground ,brown wire 0.5 Pin 10
lamda heating , brown wire 1.0 Pin 20
In the wireschematics i see a Plug in with 2 green and 1 Brown marked as CO- Poti ( M 150 )
harald

[Speedster94]

M 150
For leaded gasoline only . Maybe you have a wiring harness for this option ,that would clear why you dont have a Lambda sensor Plug in .
What is the Number on the harness .
harald

[CBRacerX]

Thanks very much for the detailed information. This is for the Euro Varioram DME, correct?

This harness does not have a part number on it, the seller removed it to keep it a "secret" because of the low cost. I didn't know that until after it was delivered, of course...

This is supposed to be a Euro 993 RS harness. Leaded gas optional connection eh? Interesting. Won't need to connect that to anything I think!

This motor was actually purchased from you, I hope to have it running soon!

Best,

Chris

[CBRacerX]

the seller mentioned that a potentiometer could be installed on the harness to use for setting the mixture manually. That might be what the "CO - Poti" is referring to!

Now the DME itself knows nothing about this explictly, so I if I provide the O2 sensor connection that it expects I would think that the mixture would be adjusted using a normal feedback loop.

Chris

[CBRacerX]

I called this morning and the rep was just looking at my email! He had all the info ready for me and we did the transaction over the phone for the throttle cable that I needed. Now I just have to wait for it to show up...

Rating: Good So Far!

Chris

[Speedster94]

on the schematics it looks like it is going into the DME Pin where the lambda goes normally . So you need the Poti to set the Mixture i guess .
I have never come across one of those harnesses ,as they are not used here , even not in a RS ,they have to be with cat to be streetlegal and also in most race series .
harald

[CBRacerX]

Bizzare. Not terrible if it works and is much less expensive than the 993 RS or Euro V-ram harness.

I have what is supposed to be a euro 993 V-ram DME. It is a 55 pin, socketed chip Bosch DME. The part number is 993.618.123.80 - is this what is supposed to be? I'm wondering what it could really be!

Thanks!!!

Chris

[Bill Verburg]

I have what is supposed to be a euro 993 V-ram DME. It is a 55 pin, socketed chip Bosch DME

That part is correct.

but the DME for an RS is 993.618.123.85 w/o driveblock or 993.618.124.85 w/driveblock.

Again I have been told that the euro M64/21(v-ram) harness is not functionaly compatible w/ the M64/20 RS w/o switching pin positions.

[CBRacerX]

It seems that I have an 993 M150 "leaded gas" Euro V-ram DME harness. This is connected to a US spec 993 Engine Harness and a Euro spec standard (non-RS) 993 v-ram DME. Whew!

I still have to look at each pinout I suppose, but in theory are these compatible?

Chris

[Speedster94]

DME for euro Vram is 99361812311 non Driveblock or 99361812411 for
driveblock . The Rs numbers are the ones Bill has .
The number you have is not known in the PET .The Engineharness has only 1 Lambda sensor ,while the US has 4 Lambdaconnectors .
I would think you need a VERY good electrician if you dont want to blow
the DME or set the Car on Fire . To me that is too much a mix up ,and it can get expensive ,very expensive .
Harald

[CBRacerX]

Harald,

Thanks for taking the time to look this up. I am going to take some pics of the inside of the DME and post them to help perhaps identify what it really is.

Cheers,

Chris

[CBRacerX]

This is the DME that I have. Not an official part number sticker, so anything is possible I guess!





I also tested out a few of the harness connections to the DME connector. Since I don't have a v-ram wiring diagram (only the '95 993) I can't tell if these are correct.

"Poti" connection (CO potentiometer)
Green - 29
Green - 29
Brown - 10

Left Knock Sensor
White - 28
Brown - 28
Black - 33

Right Knock Sensor
White - 9
Brown - 27
Black - 33

Flywheel Position
White - 44
Brown - 45
Black - Ground Lug

Head Temp
Black/Red - 48
Brown - 6