1992 3.5 v8 EFI Discovery

Thanks for helping me out, I really appreciate it. Sorry for the slow response, I've been away camping on Exmoor. Gutted I couldn't take my Disco with me
While I was away I left her at my cousins workshop. He helps me with any mechanics that I can't do myself, and he's been tinkering with her.
As an experiment he decided to swap my old downpipes for some he's got in his workshop, and see how she ran. Unfortunately he broke 1 of the 2 "weird" sensors. So he cut them out of the old downpipes and fitted the spares. Luckily the Lambda sensors came out ok and have been fitted to the "new" downpipes. The weird sensors don't appear to have any plugs, so can't be removed and are cable tied to the chassis at the moment.
My cousin has driven her for over 200 miles on petrol and LPG and she seems to run fine without the sensors in, which is great news but we still don't know what the sensors are for.
I've uploaded some pic's(I think). As you can see there is still some of the old exhaust on the sensor, but it's clear that it's not a Lambda sensor. I've also uploaded some pic's of the old downpipes so that you can see where the "weird" sensors were fitted/cut from.

How very odd indeed. Nope, never seen anything like it before!!

That's what everyone's saying

Can you trace the wires back at all?
Do the go into the main loom or do they look like an aftermarket fit?

Really don't think they are a land rover fitment otherwise I would have expected a connector futher up the loom to enable you to un plug them.

Being ex jap is it possible some boy racer has fitted an Exhaust Gas Temp guage before and just removed the guage and left the sensors there? They do look like EGT sensors..... can you see if there are two wires or three wires going to the sensor. Most o2 sensors are at least 3 wire where as a temp sensor will be two

Most old type exhaust sensors are 1 wire!!

They definitely look like temp sensors, I was thinking maybe some kind of flamer kit but just not even slightly the right sort of component!

The wires appear to go into the door pillars with no plug to disconnect them at all. Which is weird. Like you say, Landrover would've put plugs on them, but it's a lot of hassle for an add-on to thread them through the door pillars
Each sensor has 1 braided metal wire with 2 wires inside it. 1's red and 1's grey/faded blue. I've cut 1 of them out. They do look like EGT probes.
I've got the history for her since she came back here in 2004, but nothing from when she was in Japan, so I've no idea what mod's happened to her over there. Nothing's been changed inside though, no extra switches, gauges, etc.
Maybe for diagnostics?

so my 91efi shouldnt have cats??? Coz it does ... :s

my 92 efi doesnt have cats, because it's april and i think changeover was August 92, for the K plate.

regards the sensors, who knows what emissions laws there were back in japan...?

wow.. that's gay, i always thought my one was 91, it was actually made in the last weeks of Dec 92.. so its almost a 93 lol. pays to read the v5 huh...


So does it make much difference not having cats performance wise??

You've made me check my v5 now and mines March '93, which would explain the Cat's. I thought the changeover was later though(when they changed to 3.9l), but then I'm no expert. That's why I'm asking you guys

I've just had an email back from the manufacturers of the LPG system and they said;
"Hi there Steve,
The tech guys had a look and their opinion is that the “probes” are something to do with the rpi power amp(which I believe is an aftermarket addition - some kind of spark enhancer).
They based the conclusion on their knowledge of the vehicle and LPG installation, and excluded it from either as a standard
vehicle fitting or LPG, all that’s left is the RPI Power amp.
I would suggest that if it aint broke don’t fix it, if there are no management lights on the dashboard
and the lpg runs fine, then maybe leave well alone.
It might be an idea to do some research on how an rpi power amp is fitted and if it has the probes associated with it.
sorry I cant be more help but I hope it’s a start."


Er, so what do you reckon?
I'm off to trawl through the history again......

discomark10 said:

wow.. that's gay, i always thought my one was 91, it was actually made in the last weeks of Dec 92.. so its almost a 93 lol. pays to read the v5 huh...


So does it make much difference not having cats performance wise??

Click to expand...

you gain top end hp but not a huge amount

Here's some pic's of the wires on the "weird" sensors.

sidewaysste said:

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.

Click to expand...

Does yours only run on LPG then?
Mine runs mainly on LPG, but petrol for starting and running 'til warm (normally about 20 seconds with a V8)..
Therefore, the V5 log for mine states 'dual fuel'. I has assumed all converted motors would be logged the same?
So, at each MOT, the tester has to "assume the worst case scenario" and test it on petrol.....hense why mine has the cats

just my experience, but if anyone's got a .gov link or whatever, would be interested to read

Oh, and I have a similar sensor on my LPG'd brooklands.
I've never bothered investigating it to be honest, but the local LPG centre answered my questions last gas service.....it communicates with the ECU and helps "adjust to optimum running, when switching from petrol to LPG"

That's weird. The manufacturers of my BRC LPG system said that it's nothing to with the LPG and must be after-market. They seemed to think they were to do with a RPI power amp, whatever that is

As for MOT's with LPG I can only speak from experience as I've not read the legislation. I've put my Disco through 4 MOT's now and every time the emissions have been tested on gas as it's the primary fuel

Rpi power amp seems to have no available connection for EGT...

Er...What does that mean
Sorry buddy but my electrical knowledge is minimal

After you suggested it I read all about the rpi power amp and they do not and are not able to connect to exhaust gas temp sensors.

Unless this is an obscure modified version, then my money is on them not being related.

Can you not just trace where the wires go?? It's only a D1 FFS!!

I've just been out and traced them as far as I could, on the passenger side. I've also taken some more pic's.
The wire comes up through the floor in the foot wells,

View attachment 35273

It's then coiled up on the inside of the inner wing by the bonnet catch,

View attachment 35274

Then the wires go into an orange box/relay which is fixed to the inner wing,

View attachment 35275

View attachment 35276

View attachment 35277

More wires exit the box and go up into the top corner of the inner wing by the windscreen,

View attachment 35278

That's as far as I can trace them without taking the dash out. There's no sign of the wires in the engine bay

Can't see the pics