NickHodgson Posted January 24, 2007 Share Posted January 24, 2007 I am taking a V8 Auto 1997 Disco to Africa where it will run on leaded fuel. The current mileage is 86,000kms. Do I need to remove the cats? I understand that I do not have to remove them but they will be damaged and will eventually clog up. Is it possible to get the front exhaust section with no cats for this car and then what do I do with the Lambda Sensors? Thanks Nick Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 24, 2007 Share Posted January 24, 2007 I have run my cat Discovery 2 (it was built wrong) on leaded for several years with no problem, they have only just introduced unleaded here. Exhaust just smells funny that is all. You can get a non cat exhaust system for Discovery 1 because my old Discovery (1996MY) was a non cat one, and this would be the best option and may give a slight power increase. The engine ECU can be told to use a "non cat tune" using a "tune select resistor" in the wiring harness (I'm assuming it is a standard 14CUX 3.9 V8), the resistor is built in to the harness under the drivers side dash (RHD) and there are non-cat low compression, non cat high compression and cat high compression ones I think, maybe others. Simple job to change it and the ECU will then ignore the oxygen sensors and run "open loop". Quote Link to comment Share on other sites More sharing options...
NickHodgson Posted January 24, 2007 Author Share Posted January 24, 2007 sounds good. Microcat seems to say that the cat tune resistor is white but the non cat one is green. So I fit the green one and a new downpipe and even when I break the oxygen sensors trying to remove them it will not matter? Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 24, 2007 Share Posted January 24, 2007 I suggest you fit the green one, disconnect the oxygen sensors and run it for a bit to make sure it is all ok (it should be - I have just never done this particular mod) before you start wielding any more spanners Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 24, 2007 Share Posted January 24, 2007 If the lambda sensors are before the cats you can leave them in as closed-loop running will be more efficient and may help compensate for poor fuel. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 24, 2007 Share Posted January 24, 2007 I always understood that leaded fuel "plated" the HO2S with lead and so they didn't work and led to the vehicle running very rich? I didn't notice any difference between closed and open loop economy in my Discovery but that is a Thor engine of course, different EFI system entirely. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 24, 2007 Share Posted January 24, 2007 Not heard of that one, I know they don't like silicone sealant. Thor engine would be relatively new and a smarter system so you probably wouldn't notice a great change as it has other sensors that help it stay in a happy place. Older systems, on older engines, you should see a bit of benefit but then this is Lucas we're talking about the MS running closed-loop with a carp fuel map beats the Lucas system which in theory should have a far better developed map in it. Quote Link to comment Share on other sites More sharing options...
Diff Posted January 24, 2007 Share Posted January 24, 2007 It is my understanding that leaded fuel will 'poison' the cats, not physically damage them. The engine will run fine on it, BUT it is my understanding that when you return to england, you may have trouble passing an MOT emissions test because the cats won't work. I know that Stephen (bogmonster) lives in the falklands where it is my understanding that the vehicles don't have to pass the same emission tests as uk vehicles do every year. If it were me, I would definately find some replacement pipes (or have some made up) and temporarily remove the cats and refit on my return. (Assuming the pipes are a lot cheaper than replacement cats!) Aside from the 'poisoning' issue I understood that the cats had potentially fragile honeycomb cores which can get damaged by impact etc. There are often a lot of stones bouncing around under a landy in Africa, and these, coupled with the appalling vibration etc from corrugated dirt roads may hasten their internal demise. Regards, Diff Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 24, 2007 Share Posted January 24, 2007 Diff is right ^^^ mine rattle like buggery! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 31, 2007 Share Posted January 31, 2007 What does buggery rattle like? Quote Link to comment Share on other sites More sharing options...
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