farmershort

farmershort

Well-Known Member
Hi All,

I've been wondering about the Lambda sensor positioning for my rebuilt v8. The loom and ECU is all circa 14CUX 1994 3.9 disco v8. The problem comes with the introduction of a new manifold - I've bought some hedman headers, and obviously they're quite long, and are 4-1 configuration.

I assume that the normal position for a lambda sensor would be at the collector, just after the standard manifold. With long primaries, does this logic change? Is there another configuration option?

Oh, the engine was originally a 3.9 efi from above disco, but is now a 4.6.
 
I have 4-1 headers on mine, don't know what make they are but the hole for the sensor is at the collector, as mine is a non-cat car I just plugged the holes. Anyway, my other half is using the car today but will take a pic later if you like.
 
Hi Kev, yes a pic would be great if you can manage it. My engine in from a 1994 Disco, and my shell/chassis is of 1998 defender vintage, so whichever way you slice it - I need a cat. Which means I've got to get this sensor stuff planned out properly.
 
Fitted as shown from the factory.

image.gif
 
I'd check with my tester. Not sure whether cat presence visual inspection would apply (though a cat with its guts knocked out would pass visual). As far as emissions go, before Aug 94 is 3.5% co 1200ppm hc same as any car post 1986. The car will be emissions tested based upon the date of the engine, not the tratter (whichever is earlier) so the onus is on you to provide the evidence (log book)which I assume you have since I've seen the scrap yard on your driveway :)

If yours is earlier than those listed below, the above test applies:
LAND ROVER
The Model Code consists of the 4th & 5th digit of the VIN number and defines the model. The Serial Number consists
of the last 6 digits of the VIN number found on the VIN Plate. The Engine Code consists of the 8th digit of the VIN
number and defines the engine type.
Discovery Model Code LJ
2.0l LTi Engine Code Y 0.5 1000 500 0.3 200 0.95 1.09 3000 70 2500
3.9l V8 Engine Code M Serial number 117885 onwards 0.5 1000 500 0.3 200 0.95 1.09 3000 70 2500
Discovery Model LT
All engines 0.5 1000 500 0.3 200 0.95 1.09 3000 70
 
I think as long as they are close to the down tube all is fine, to be fair what can change in 12 inch of enclosed exhaust tube.
My RRC runs a lambda on its LPG system and that can be in the Y tube before they meet off course.

If you need a lambda boss to weld in Tinley Tec sell thm
 
Pete - yes I need a boss welding on each collector, I was going to ask zircotec if they can do it just before ceramic coating.

Cooltide - cheer for that. The scrap yard on the driveway is now just the old chassis from the 1998 defender. The disco which donated the engine used to belong to a member on here, but he's long since broken it and got rid. We're in talks trying to track down the copy of the log book, but at the moment I have to assume that all I have is the email from him confirming the sale and the reg number of the disco.

I guess I could always try and get hold of a gas tester and see what the emissions are like.
 
O.K. I tried to get a pic but it is not the best. This shows the right hand side manifold collector, you can see the bolt in the top which is where the O2 sensor would go, there is a similar boss on the other manifold. Unfortunately, there isn't enough room to get a clear photo from the top so hope this is enough to give you an idea.
Also, if you decide to run without O2 sensors you will need to change the tune select resistor and adjust your air flow meter.

HTH
IMG_0001.JPG
 
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