1992 3.5 v8 EFI Discovery

edwardbahaw · Post by **edwardbahaw** » Wed Jan 11, 2012 3:05 am

Hello all

Recently purchased a 1992 3.5 v8 EFI Discovery which is in good working condition.

I went underneath and noticed that the O2 sensor is fitted on the exhaust but is unplugged on the other end.

I was hoping to plug it back in just to see if it makes any difference but can't seem to find where it plugs into.

Can anyone here suggest where the connection might be located?

Much appreciated

Ed

robp · Post by **robp** » Wed Jan 11, 2012 11:05 pm

Hi Ed

Got a 3.5 efi myself

standing at the front of the motor look at the bulkhead around the rocker covers. There should be a round three pin plug that hands down from the wiring loom attached to the bulkhead on each side of the engine.

If you cant find it I can try and take a pic at the weekend

Rob

edwardbahaw · Post by **edwardbahaw** » Fri Jan 13, 2012 2:23 am

Hi Rob

I look forward to seeing the pic!

In the mean time here is a pic from underneath showing the sensor on the exhaust pipe.

https://docs.google.com/leaf?id=0B7ltZi ... 1&hl=en_US

Ed

edwardbahaw · Post by **edwardbahaw** » Fri Jan 13, 2012 5:02 pm

Hi again

Was doing some checks under the hood and came across some taped up wires. Not sure what they are supposed to be connected to. Maybe the O2 sensor(s) perhaps?

It's basically two sets of 5 blue wires which are bridged together and taped up.

Both sets seem to be connected to the main loom which goes inside the firewall supposedly connected to the engine ECU.

Here is a pic! Not sure if any one of you would recognise them.

https://docs.google.com/leaf?id=0B7ltZi ... 1&hl=en_US

Regards
Ed

DaveEFI · Post by **DaveEFI** » Fri Jan 13, 2012 5:18 pm

That link requires you to register to view. Photobucket and others have a direct link facility to a single pic.

robp · Post by **robp** » Fri Jan 13, 2012 8:28 pm

DaveEFI wrote:That link requires you to register to view. Photobucket and others have a direct link facility to a single pic.

Even if you are registered on Google docs it returns the error documentt not available.

As for two sets of 5 blue wires bridged. Unless a previous owner has done a load of wring changes then thats not them

Will get a proper picture in the light tomorrow but this is a picture copied from the LR rave workshop manual. The conector on the RH bank is arrowed as C113 n this pic

Rob

SimpleSimon · Post by **SimpleSimon** » Fri Jan 13, 2012 9:47 pm

You may find that the sensor as also been unplugged because someone as chosen to run on the non-cat map, is the catalytic converter still fitted?

edwardbahaw · Post by **edwardbahaw** » Sat Jan 14, 2012 3:33 am

K guys, I got links from photbucket now!

Here is a pic of the y pipe with no cats but an O2 sensor screwed into it but not plugged to anything on the other end.

http://s1078.photobucket.com/albums/w49 ... Sensor.jpg

Here is a pic of the wires which have been bridged and taped!

http://s1078.photobucket.com/albums/w49 ... pwires.jpg

Looking forward to your replies now that you can see what I see!

Ed

DaveEFI · Post by **DaveEFI** » Sat Jan 14, 2012 9:02 am

That looks to me like an addition - a wideband for use with a MegaSquirt, etc? Or just to monitor the actual AFR?

The wiring also looks like an addition - perhaps to do with an alarm?

robp · Post by **robp** » Sat Jan 14, 2012 1:06 pm

That O2 sensor is not standard fitment in that position.

I used to have the cat downpipes on my '93 and then removed in favour of non cat.

I don't believe the non cat downpipe has an O2 sensor position (mine doesn't!) so that looks to have been added afterwards. On the cat downpipes there are two sensors. One on each of the downpipes just after the cats.

I cant see that the O2 sensor you have in that position would ever reach the standard plug up on the bukhead. So as dave suggests I suspect that it is an add on.

Also those wire are definitely not the standard sensor wires either

shaunod · Post by **shaunod** » Sat Jan 14, 2012 5:49 pm

Certainly not a standard fitment .. and also does not look like a wideband .. if it has three wires coming out of the sensor .. one black, one white, one red, then it is a standard narrowband sensor that looks like it has been put in as an afterthought. As for the blue wires .. again certainly not standard .. have you got a wider angle picture to show where they are going? Also a picture of the ECU and the first 12" of the loom next to the ECU would help.