MOT Failure - Emissions and lpg?
Discussion
Hi Guys,
Bit confused here. My '98 Range Rover 4.6 has just failed the MOT on emissions (CO too high), despite it running on lpg. The tester didn't seem to know anything about lpg which worried me a bit.
The printout for the emissions shows the fuel type as Unleaded. Shouldn't it be LPG as I understand this gives higher allowed CO limits (something to do with it being tested in the non-cat category)?
I know it should pass on the standard test, but the previous owner emptied the cats and it's never had a problem before, even at the same test centre.
Fast Idle Test CO - 1.01% (shown max allowed is 0.3)
Second Fast Idle Test CO - - 1.08% (shown max allowed is 0.3)
Natural Idle Test CO - 1.34% (shown max allowed is 0.5)
I've found a few articles that suggest if the fuel type was lpg, then the max allowed would be 3.5%
I've done some reading around but can't find a definitive answer.
Anyone know the real story?
Guy
Bit confused here. My '98 Range Rover 4.6 has just failed the MOT on emissions (CO too high), despite it running on lpg. The tester didn't seem to know anything about lpg which worried me a bit.
The printout for the emissions shows the fuel type as Unleaded. Shouldn't it be LPG as I understand this gives higher allowed CO limits (something to do with it being tested in the non-cat category)?
I know it should pass on the standard test, but the previous owner emptied the cats and it's never had a problem before, even at the same test centre.
Fast Idle Test CO - 1.01% (shown max allowed is 0.3)
Second Fast Idle Test CO - - 1.08% (shown max allowed is 0.3)
Natural Idle Test CO - 1.34% (shown max allowed is 0.5)
I've found a few articles that suggest if the fuel type was lpg, then the max allowed would be 3.5%
I've done some reading around but can't find a definitive answer.
Anyone know the real story?
Guy
I had this once before, The tester did not realise it was lpg and kept the revs up high waiting for the readings to drop? it was at this time i told him it was running on lpg and and he passed it. Was the tester aware it was on lpg? and have you questioned it saying unleaded on the printout?
cahami said:
I had this once before, The tester did not realise it was lpg and kept the revs up high waiting for the readings to drop? it was at this time i told him it was running on lpg and and he passed it. Was the tester aware it was on lpg? and have you questioned it saying unleaded on the printout?
I did explain that it was lpg at the start but I didn't realise what that actually meant at the time. For some reason, I thought it would actually lower the CO settings, but having read up on it that's obviously not the case.I didn't think to look at the fuel type until I got to the office and started investigating. I'm trying to confirm that this is actually right before I go back and speak to him - as I mentioned, he didn't know anything about lpg so I'm hoping he just didn't know that he had to change the fuel type on the gas analyser.
He was revving the bejeesus out of it for what seemed like hours.
As a tester. You test "as presented" If it comes in on LPG you test as a LPG
CO Under 3.5%
HC under 1200 ppm
From the book said:
Vehicles which run on more than one fuel(e.g. 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 emitted 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 reading of 700 ppm. The PEF marked on the machine is 0.48. So the actual MOT value is: 700 0.48 = 1458 i.e. fail
Some exhaust gas analysers have an automatic facility for doing this
FYI (and as I understand it) Limits for LPG areSome exhaust gas analysers have an automatic facility for doing this
CO Under 3.5%
HC under 1200 ppm
Edited by Rich_W on Thursday 6th October 21:12
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