1993,Disco V8 Lpg emissions test failure

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G

Grafell

New Member
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5
Location
Corby,Northamptonshire
Hi,can anybody out there help!!!
A friend of mine has a 1993 Disco V8 which is fitted with an LPG conversion.
The car is a left hand drive built for the german market.The car is now residing in France where it has failed its CT (french equivelent of mot) on exhaust emissions.Lambda level high.
The car does is an EFI model.There are no 02 sensors on either front pipe and no visible wiring to suggest that the car has been de-catted.There is however a sensor that was fitted at the same time as the LPG conversion immediately in front of the main silencer.
Is there anybody out there that can tell me if this car ever had cats fitted and is the sensor it does have a lambda sensor?
The co emission on test was 0.99%.
Thank you,Gray
 
goonarmy said:
in the uk if presented on lpg it wont fail emisiions.
Click to expand...

An out of tune LPG fueled engine can fail the emmissions test the same as a petrol engine.

This is a copy from the Testers Manual.
Vehicles which run on more than fuel (eg petrol and LPG) should be tested on the fuel they are running on when presented.

There is a slight difficulty with LPG vehicles: the hydrocarbons are propane rather than hexane. So the HC reading obtained must be divided by the propane/hexane equivalency factor (PEF) marked on the gas analyser. For example:

An LPG vehicle gives a HC reading of 700 ppm.

The PEF marked on the machine is 0.48.

So the actual MOT value is

700/0.48 = 1458 ie fail. :mad:

Some exhaust gas analysers have an automatic facility for doing this.
 
A high lambda reading indicates a leaky exhaust,but it should be able to get down to 0.5 % Co without Oxy sensors/Cats.So,it could just be a partial misfire OR a small adjustment on the trimming screw on the AFM.
Put the chassis # into Microcat to see if it was open or closed loop as supplied new.
 
I put mine in for the MOT a couple of weeks ago, presented it on LPG. The tester told me he had a bit of trouble with the emissions at first. The car had been standing for a couple of months so he gave it a bit of a blast and bingo it passed. Maybe that's all that your friend's truck needs.
 
Hi,thanks for your replies.The main problem is that the car is in france and my friend,the owner wants to french register it.According to the Tester in france the car has to be tested running on petrol thus the problem.On lpg it is fine but the french will not accept this for testing.
 
discool said:
I haven't a clue what it means as I never been interested, but when my disco emmissions are tested the resuilts of the test are C0 0.00, HC 11ppm and Lambda 1.01.
Click to expand...
Your CO is a bit low,.2 or .3 would be a tad richer,the HC at 11ppm means all 8 pots are burning nearly all the fuel and the cats are finishing off nearly all the rest.The Lambda reading of 1.01 is slightly on the lean side of 14.7/1 air / fuel mix. 1/1 is "perfect" Stoichiometric - yours is as close as you can realistically expect.
 
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