bigal13

hi

i have a 1986 944s i went to replace my oxgen sensor only to find that there is NOT one fitted
i thought these cars were fitted with DME system and has adaptive oxgen sensor control (idle speed and mixture are electronically controlled)

the exhaust has the hole for fitting one capped off with a bolt BUT there is no sign of where to fit the other end of the sensor

so one end goes into the exhaust but where does the other end go



or is it a case of i dont need one
or is it more like who ever fitted the exhaust never fitted the oxgen sensor (i only got the car 8 weeks ago so dont know who fitted the exhaust)
or is it that my car does not have a cat converter fitted

HELP alan

DLarsen

All 86 944's have a O2 sensor. They are part of the Bosch DME system. Sounds like the previous owner removed and plugged the opening in the exhaust. The O2 sensor wire is routed up into the engine compartment (the back part of the engine). There should be a round electrical connector thats mounted to the firewall that would receive the O2 connector end. I would suggest buying an OEM type O2 sensor and not a universal. Universals sensors have to be cut/spliced to your OEM electrical connector.

bigal13

hi

is there any chance of you posting a picture of where the conection is at the firewall

alan

awilson40

Depending on where your car was imported from/to you may not have an o2 sensor or Cat. Sense you are in the UK, this is a very good possibility.

83na944

Are you sure about that, awilson? I thought that even DME systems without a catalytic convertor need o2 sensors to control the mixture.

Big AL, do you have a catalytic convertor? My 83 has two ports on the exhaust. One for the o2 sensor and one for a sampling tube that is capped off.

dgz924s

Cat doesn't matter. The O2 bung is located before the cat. It is needed to control mixture otherwise the DME goes into a default setting is how I understand it. But since you are driving a Euro model the cat may not be required and the air mixture controlled elsewhere....DME?...... Dal

Travis - sflraver

With our DME, the o2 sensor plays a minimal role in controlling the fuel mixture. It is more of a "just enough" add on to make the EPA happy in the 80's.
Some of the newer cars are much more dependent on that signal just to be able to run at all, which is not the case in the 944.
As Awilson up there said, since you have a "ROW" car it is likely that you do not have the o2 sensor.
As for a sensor bung... only the ROW turbos had the bung still installed but capped. The NA cars had their own exhaust piping with no bung at all (ROW cars).

bigal13

hi

here is a picture of the front pipe where the oxygen sensor should be

bigal13

hi

i dont think i have a cat as far as i know they were only fitted to 1989 cars onwards

pic of tail pipe & middle section of exhaust

bigal13

hi

can anyone take a picture of the O2 sensor where it plugs in at the bulkhead as i cant find anywhere for it to plug into

so i am suspecting that i dont need one BUT then how does the DME control the mixture????

83na944

On my 83 its a big, round, ceramic connector that's held by a clip to the firewall. Right in the center.

bigal13

hi

not much room there as you can see i dont have a connection either


so how does the DME work

awilson40

the only purpose for the O2 sensor control is to regulate the mixture tight enough so not to damage the cat...no cat, no need for the O2 sensor feed back, the DME runs off its own programmed fuel maps.
Check out the chart from the service manuals. The 944s also has a coding plug to select different fuel maps depending on the country.
If you have no cat, then you have no need for the O2 sensor. Find your computer and see if its jumped with the connector as per the chart.

bigal13

hi

awilson40 thats cleared that up for me

by computer do you mean the DME at the passengers foot well (left hand side on a uk car) but i dont understand the chart

alan

awilson40

Yep, thats the computer, the large connector shown plugs into the DME computer. Theres (2) 2 wire pig tails comming off with connectors on them.
These may or may not have jumpers or resistors plugged into them to select the different maps for the different countrys. That way one computer will work the world over.
In the USA, we have nothing plugged in either connector, signifying a USA market car with Cat and O2 sensor.
The chart shows which connector is used for the various markets.
You probably have part number 928.607.422.00 connector plugged into the 'varient switch' cable for an EC non CAT car