1992 3.5 v8 EFI Discovery

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

Good Morning!

I have exactly the same Disco as you, the 3.5 EFi on a 1992 shouldnt have any 02 sensors hense why you cant find an electrical plug/lead, whats probably happened at some stage of its life is its had the exhaust off a later disco that does have 02 sensors on it fitted to it, and they found the only way of blanking off the hole is just to put a sensor in there instead of using a proper blanking plug, not that it makes much difference whats in the hole if its just there as a blank?

Hope that helps?

edwardbahaw said:

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

Click to expand...

Hello Ed

Welcome to the "in my opinion best version of Discovery ever made" club.

200 body - very simple (very rusty aswell though lol)
3.5 engine - very reliable.
1992 - just old enough to not have any kind of emissions regulation, new enough to have beige interior (in my case)


So, has yours got cats in the downpipes?

Cos if it's got O2 sensor holes I assume it's got cats in the pipes too? That is WELL GAY, you must get rid of them immediately so that when you start the car up in the workshop it immediately makes your eyes bleed.

Ah the joys

Thanks for the replies thus far!

Here is a pic from underneath which shows the location of the oxygen sensor on the exhaust pipe!

Ed

Interesting! It looks like it's got the old type non cat Y pipe on it, so can't imagine why that sensor would be there.

Also looks to be a nice car, not a lot of rust about in that pic!

Interesting! very interesting as it's not shown in any of my rangy or disco part books or workshop manuals.

Mr Noisy said:

Hello Ed

Welcome to the "in my opinion best version of Discovery ever made" club.

200 body - very simple (very rusty aswell though lol)
3.5 engine - very reliable.
1992 - just old enough to not have any kind of emissions regulation, new enough to have beige interior (in my case)


So, has yours got cats in the downpipes?

Cos if it's got O2 sensor holes I assume it's got cats in the pipes too? That is WELL GAY, you must get rid of them immediately so that when you start the car up in the workshop it immediately makes your eyes bleed.

Ah the joys

Click to expand...

Or you could get a 3.9, convert it to LPG and then legally bin the cats, like wot I did

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.


Regards
Ed

Odd. Pull your ECU plug and see if you have the wiring in the plug for O2.

The pinouts can be found here:

Rover 14CUX Hot Wire Mass Flow EFI: Service and Troubleshooting

Makes for an interesting read too, it's worth checking your efi system over whilst you got the multimeter out

sidewaysste said:

Or you could get a 3.9, convert it to LPG and then legally bin the cats, like wot I did

Click to expand...

But now if it left the factory with cats they have to be fitted for the MOT

You are all barking up the wrong tree!
Land rover never produced a single ox sensor in that location looks more like it had a single point gas system with lambda sensor detection but was fitted so the sensor sensed both sides of the engine rather than one like most crappy system do!

Mr Noisy said:

Odd. Pull your ECU plug and see if you have the wiring in the plug for O2.

The pinouts can be found here:

Rover 14CUX Hot Wire Mass Flow EFI: Service and Troubleshooting

Makes for an interesting read too, it's worth checking your efi system over whilst you got the multimeter out

Click to expand...

Thanks so much for this link ... great information here!

One question though ... where would I find the Electronic Control Unit and the Fuel Injection Fault Display on this discovery?

Thanks in advance!
Ed

edwardbahaw said:

Thanks so much for this link ... great information here!

One question though ... where would I find the Electronic Control Unit and the Fuel Injection Fault Display on this discovery?

Thanks in advance!
Ed

Click to expand...

ECU is fixed to the side of the inner wing, just above and to the right of the accelerator pedal.

Look under the dash and you'll see it.

As for fault display, your car probably doesn't have one. American spec range rovers had to be fitted with them by law, nothing else did. So, some range rovers have the wiring in the ECU loom and a plug fitted to connect the fault code reader, but as far as i know discoveries don't.

Again check your pinouts on the ECU plug to see if it has the diagnostic wires fitted. If so, you need to trace the loom til you find the plug.

By the way, I agree with stu that this car probably had LPG fitted and the lambda sensor was for that. May also explain those blue wires cos they certainly don't look factory...

discool said:

But now if it left the factory with cats they have to be fitted for the MOT

Click to expand...

Not if it's documented on the v5c as being equipped with LPG. If it is, it must be emissions tested whilst running on LPG and it will be running so clean that it won't need cats.

Hello everyone,
I also have a '92 3.5l v8. Mine has been converted to LPG and until 12-18 months ago she has run beautifully.
In the last year I've done the head gaskets, thinking that was the problem. Recently I found out that it's the cat's that are the problem.
My v8 is set up differently from the standard '92 version, I think it's because she was a Japanese export. There are 4 sensors on the down pipes. 2 each side, 1 before the cat and 1 after it.
I can't find anywhere that sells a part with the correct amount of sensors mounts.
Are the "extra" sensors there because of the LPG conversion and can I get rid of the cat's?
Help please?

flashpanach said:

Hello everyone,
I also have a '92 3.5l v8. Mine has been converted to LPG and until 12-18 months ago she has run beautifully.
In the last year I've done the head gaskets, thinking that was the problem. Recently I found out that it's the cat's that are the problem.
My v8 is set up differently from the standard '92 version, I think it's because she was a Japanese export. There are 4 sensors on the down pipes. 2 each side, 1 before the cat and 1 after it.
I can't find anywhere that sells a part with the correct amount of sensors mounts.
Are the "extra" sensors there because of the LPG conversion and can I get rid of the cat's?
Help please?

Click to expand...

Yes, two O2 sensors standard fit with the cats and sound like two for the LPG.
As LPG burns cleaner and yours is a 92 you could fit a non cat downpipe and get a couple of O2 sensor bosses welded on and refit the LPG O2 sensors

Thanks for replying
I've taken the extra 2 sensors out and they look like temperature probes(thermal couplings). They are totally different from the Lambda sensors. I spent ages on the phone to "Rimmer Bros" earlier and they don't think that they are standard and must be something to do with the LPG system.
The garage that fitted the system has ceased trading, but the garage that is there now fit LPG and they don't think that the sensors are to do with the LPG system. I am now in contact with egasweb who made the system and I'm waiting for a reply.

the jap ones do as std p38 is the same ,i belive it warns of cat failure

Ah! That would make sense as mine is a Jap' export. Thanks
If they warn of cat' failure they couldn't have been working anyway though. My cats are knackered and I've had no warning lights.
Are they temp' probes and are they the same as P38 ones? Do I need them at all

Most modern cars have four sensors (if they are a V engine) and all the second sensor does is monitor oxygen levels in reference to the front sensor, as james says to check cat efficiency.

however, it could be that a primitive method was to measure EGT and if it was found to be hotter than upstream sensor then it is assumed cat is working ok.

lets have some pics of them, might recognise them/the plugs