fishey Posted August 15, 2011 Share Posted August 15, 2011 Anybody know the thread size an pitch for an oxygen/lambda sensor for a series 1 disco 3.9 V8? I need to buy some boss's so i can mount the sensors in my exhaust in my 90. Quote Link to comment Share on other sites More sharing options...
zardos Posted August 15, 2011 Share Posted August 15, 2011 From a quick measure of the ones I took out of my disco 1 v8 would say M12 x 1.5 but I don't have a M12 fine nut to double check that. Quote Link to comment Share on other sites More sharing options...
knacker Posted August 15, 2011 Share Posted August 15, 2011 When we fitted a Disco 3.9 in our 90 we changed the tune resistor so we didn't have to fit the cats. Jon Quote Link to comment Share on other sites More sharing options...
zardos Posted August 15, 2011 Share Posted August 15, 2011 When we fitted a Disco 3.9 in our 90 we changed the tune resistor so we didn't have to fit the cats. Jon True you can do this but depending on the age of the engine and on what you do / Tell the DVLA about then the emission level might be set for a engine with cats. Quote Link to comment Share on other sites More sharing options...
fishey Posted August 15, 2011 Author Share Posted August 15, 2011 What is this about tune resistor? Not something I've come across? I was just going to fit downpipes without cats in and fit the sensors. The sensors are before the cats anyway aren't they, so it shouldn't matter if you have the sensors without the cats? Quote Link to comment Share on other sites More sharing options...
zardos Posted August 15, 2011 Share Posted August 15, 2011 What is this about tune resistor? Not something I've come across? I was just going to fit downpipes without cats in and fit the sensors. The sensors are before the cats anyway aren't they, so it shouldn't matter if you have the sensors without the cats? The tune resistors changes the ecu behaviour for a car with cats, the resistor is circled in below picture. See http://www.v8engines.com/faq-inj.htm#tuneresistor for more details. But if you have cats, then you need lambda as cats don't like being passed un burnt fuel and the lambdas allow the ecu to adjust fuelling. So you can have the sensors without the cats but you might have problems at MOT time on emissions without the cats. And yes the Lambdas are before the cats in the pipe. Quote Link to comment Share on other sites More sharing options...
fishey Posted August 15, 2011 Author Share Posted August 15, 2011 So where can I get the tune resistor that I would need to run without sensors? How much do they cost? Is there any negative effects in doing this? Quote Link to comment Share on other sites More sharing options...
knacker Posted August 15, 2011 Share Posted August 15, 2011 We did away with the sensors and cats and have tubular manifolds that we had off another project. It's had no problems with emissions having changed the resistor, sent the V5 off with new engine number and cc and it came back changed nothing was said about any emission level. I got the resistor from a local Landy specialist, i was suprised they had one in stock. Carn't remember how much it was but i can remeber being surprised how cheap it was. Jon Quote Link to comment Share on other sites More sharing options...
zardos Posted August 15, 2011 Share Posted August 15, 2011 Down sides of no Lambda is that the fuelling might not be optimal in some conditions, thus a probably a slight loss in power and increase in fuel consumption, but this is marginal. DVLA won't tell you anything about emissions, it's only when the MOT tester or his computer to says what type of test you need (cat or non cat) will you really find out. The MOT tester's manual (http://www.motuk.co.uk/manual_730.htm) says "Vehicles Fitted with a different engine Test according to which is older, engine or vehicle. e.g. A 1995 car fitted with a 1991 engine (of whatever make), test to 1991 standards for emission purposes. Note: The onus is on the vehicle presenter to prove engine age." So if your car or you can prove the engine age is before 1st August 1992 then you can have a non cat test, if both are newer then you will need cats for the MOT. If you need cats, then you need Lambda's PS I have a 3.9 with no cats or lambda sensors in a 90 that was registered before 1st August 1992 so I can get away with no cats. Quote Link to comment Share on other sites More sharing options...
fishey Posted August 15, 2011 Author Share Posted August 15, 2011 Righti have found a green tune resistor on rimmer brothers for £13.60 delivered, i will do this for the time being as i am just trying to get it running. It is not planned to be used on the road for the near future so mot is not a major issue, can always swap back to standard tune resistor, cats and sensors at a later date. The truck is a 'K' reg and eninge is 95, so it will need them for mot at a later date. Cheers for the help! Quote Link to comment Share on other sites More sharing options...
ThreeSheds Posted August 16, 2011 Share Posted August 16, 2011 Righti have found a green tune resistor on rimmer brothers for £13.60 delivered, £13.90? I would get one from Maplins for about 13p... A ten second google found this which sound right: The Green tune resistor value is 470 Ohms, and White tune is 3900 Ohms. Ordinary 1/2 Watt resistors are just fine, although the original is a Metal Oxide 2% item (which I always use anyway). In this location I sometimes use a 1 Watt resistor, because the larger physical size makes them easier to handle. but I would check from other sources... HTH Roger Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.