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O2 Sensor


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I found the O2 sensor and connector in the engine bay, but no opposite wire to the DME unit. After opening up the connector at the DME unit, I confirmed all the connections, and no connector nor wire exists for the O2 Sensor. The car runs fine, although I can smell what I consider rich fuel from exhaust. Is it critical (better...) to have the connection for the sensor in an '84 911? If so, what is the best method to re-establish the link, as I doubt fishing through the conduit is viable?



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  • 1 month later...


1983 factory wire looms on ROW cars without catalytic converter aint have the O2 Sensorcable,

In 1984 the sonsorcable came with all cars yet ROW without CAT had the cable rolled up into the rear DME wireloom you can find it mostly behind the rear Fuse box carrier.

1985,5 the wirloom changed the O2 Sensorcable from a single spade conector on the end of a single braided wireloom (RF shielding) to the 3 prong Canon rubber connector and the O2 senors got a preheating yet no seperate ground via wireloom. on 85on cars you will find a plastic connector clamp on the left main beam on non CAT cars there is a rubber cap with a resistor wire loom on the socket.

Pre 85,5 cars have a sheet metal strip clamp for the O2 wire. However 1985, 1985,5 and 1986 is a bit "unsharp" seems Porsche used up some 85 wirelooms in 85,5 and some 86 cars as well.

Normaly if you have the new dash with the large outher vents you have the 85,5 DME wireloom.


Edited by IXXI
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Thanks for the response - how do I tell which part of the year my '84 RoW was built (i.e. whether it's an '83.5 or early '84)? The car appears to have a CAT with the O2 Sensor installed (including the wire to the engine bay, but nothing else to the DME). Does that make sense? Would the CAT be doing anything if the O2 sensor is not connected?

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the VIN descripes the build year, officialy the Modelyear runs from main vaction to main vacation wich is mostly late summer. So cars build after august/September are from the coming new year.

The 1984 Year has the Code E, 1985 has E, 1986 has G,,

Now the 3,2L build before the august are build in sequence with SC and run as 1984 Models yet those cars have time stamps around July 1983 and some preproduction specials (Like the smaller SC Brakes and the Trany without oilcooler).

The main difference is that the DME wireloom is much thiner and routet trough the CIS wireloomhole.

If you want to go sure about the build month just pull the clock or the Tank instrument and check the Date Stamp it will show year and month. Instruments whern´t shiped just in time so Porsche stocked them inbetween however the Porsche date stamp tells when the stock was inspectet by Porsche and moved to the production line so 1 to 5 days after the date stamp they went into the car.

However pre 85 ROW came without Cat so someone retrofittet the Cat with the O2 Sensor the question is who has done it and how? The factory had several upgrade Kids, your 1984 ROW should be a 231HP 10,3:1 CR engine wich was made to run 98 ROZ and needs adjustment with the fuel Quality switch to run 95ROZ.

Factory installation adds tree stickers one to the engine bay showing new specs and one to the fuel flap and the Fuel instrument gauge showing the needed fuel quality. Also you get a inlay for the manual and the TÜV approval for the maintenance book. As the factory swaps the complet DME brain it will have the correkt sticker and Order #.

Now the factory offered two retrofit Versions the early ones ratet with 208HP as the 9,5:1 CR US versions and used the very restrictive Catalytic Converters, later the factory used the improved Converter and the kit was ratet 220HP with 95ROZ Fuel. Beside the factory some Porsche Tuners and indipend Exhauts companys also offered Retrofits for ROW with TÜV approval. The difference is the factory kits swaped the complete DME harness and the DME Brain to the newer Versions, the aftermarked Version where much lower in Price and had mostly a additional O2 sensorharness and a remaped chip to be switched into the original DME Brain.

Now here comes a funny thing the 3,2L 231HP versions could pass the US Emmisions without a catalytic converter just equiped with the secoundary air pump (Swiss, Norway, Sweden versions) and using the much cleaner european fuel.

So some US Grayimprters just added a used Ctalytic converter and passed the Emmisons test without problem as long they had enough german fuel in the tank. So the Catalytic Converter was just there to make ist trough the visual test and the US emmisions test with the blue pill in the exhaust was easy to pass even a 4 Gas tester like used in germany would indicate a working system as long noone woud check it on the rolling road or test if the O2 sensor can regulate rich and lean within the allowed timeframe. So if the 911 was delivered to 49 US Staates without the smog Nazis noone would care if the system actually works.


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