How many PPM should a well running LPG system give for the emissions test at MOT?
If you mean the HC (unburnt hydrocarbons) figure the limit is 1200 but usually it will be down into the low 100's so 200 ppm is pretty good (mine read 241ppm at the last test) but I would expect a recently installed multipoint system like you have to be better than my singlepoint. It is a test of how efficient the combustion is so will be affected by things like worn spark plugs, tired HT leads, etc.
Last year mine was 28ppm. I forgot to write it down this year :/
Ah, it's hydrocarbons. My test doesn't say what it's measuring, just that the measurement is PPM.
It came in at 117PPM and I wasn't sure if that was right given that the limit is 1200! Seemed far too low to be a feasible reading.
Guess not.
CO also came in at 1.197% out of 3.500% max allowable.
Pretty chuffed - I wasn't even sure the LPG was working when they came to pick it up. The system was beeping at me when I turned it on.
Two advisories: one brake line was covered in grease/dirt so they couldn't properly assess its condition and there's a slight oil leak from the back of the engine.
As I've just replaced the head gaskets and the valley gasket I'm going to assume for now that those are fine.
Besides the rear crankshaft oil seal is there much else at the back there that would leak oil?
Surprised that it didn't get an advisory for split ball joint boots. I noticed them when I replaced my brakes earlier in the year and bought the parts. I mentioned it to them and said I've put the parts in the car in case it needs them. Nothing mentioned on the advisory list though.
Looks like you are running a touch rich on LPG, mine came out at 0.237% CO last time but in the past I've seen it down in the 0.05% region. CO checks the mixture, the higher the figure the richer it is running but you'd probably find that just changing the air filter would drop it further and get it below 1%. The HC figure is unburnt hydrocarbons in parts per million so shows combustion efficiency. They check both to stop you fiddling the figures. If the CO was high you could reduce it by 25% on a 4 cylinder engine just by pulling one plug lead off but if you did that the HC figure would go through the roof. Mind you, thinking that through, if you disconnected the fuel injector too.......
Not a lot at the back of the engine to leak other than the rear main seal or the sump, although a leak from the front of the engine from the oil pressure switch or pressure relief valve O ring tends to appear at the rear as airflow around the engine blows it to the back. If it isn't marking it's territory, I'd ignore it. Oil leaks have only recently been added to the MoT test so just about every tester is giving advisories on anything that isn't spotless underneath.
It's had a new sump gasket too - had to fish a screwdriver bit out after my bit holder disintegrated while assembling the top end.
TBH I've no idea if it's marking its territory - I've not driven it since I out it back together. The MOT was its first journey.
The running rich thing might be to do with idle speed. When I bleeding the coolant system this morning I noticed that it seemed to be holding the revs when revving the engine. I'd blip it, they'd rise, then fall and at around 1500rpm they'd kind of hover and then drop more slowly. Once or twice the revs got stuck at 3000 or so, even though the pedal was no longer pressed and the cable at the throttle body end was resting against the stop. Had to switch the engine off when that happened.
Need to look at that but I just needed it running for the MOT at that point. MOT guy didn't mention any problems when he brought it back though.
Disconnecting a spark plug and injector to lower emissions would lead to very lumpy running engine and possible warning lights/error codes (on a more modern car) wouldn't it? I'm sure that would give other problems for an MOT.
On a more modern car, yes it probably would, but as you know, I'm not into modern cars, I'm into ones that you can actually work on......
RutlandRover wrote:
It's had a new sump gasket too - had to fish a screwdriver bit out after my bit holder disintegrated while assembling the top end.
TBH I've no idea if it's marking its territory - I've not driven it since I out it back together. The MOT was its first journey.
The running rich thing might be to do with idle speed. When I bleeding the coolant system this morning I noticed that it seemed to be holding the revs when revving the engine. I'd blip it, they'd rise, then fall and at around 1500rpm they'd kind of hover and then drop more slowly. Once or twice the revs got stuck at 3000 or so, even though the pedal was no longer pressed and the cable at the throttle body end was resting against the stop. Had to switch the engine off when that happened.
Need to look at that but I just needed it running for the MOT at that point. MOT guy didn't mention any problems when he brought it back though.
Disconnecting a spark plug and injector to lower emissions would lead to very lumpy running engine and possible warning lights/error codes (on a more modern car) wouldn't it? I'm sure that would give other problems for an MOT.
You wouldn't really need to disconnect the spark plug, just the fuel injector would be enough on an injected car. Though on a modern car that would bring the MIL on anyway, which would fail the MOT.
Given the performance (or lack of) when one of the spark plugs was ejected out of the Galaxy i've also got, running it on 3 cylinders somewhat hits the performance - lumpy running with a real lack of power. You might get away with it on something with more cylinders, though it would probably still be noticeable.
The last MOT my Disco had struggled slightly on petrol to pass, tester was hesitant to test on gas but decided to try once I'd guided him away from the cng options on his tester towards the lpg ones, It passed on that with what turned out later to be a dying coil pack (probably the cause of the original failure on petrol, combined with a cat thats seen better days).
RutlandRover wrote:
Surprised that it didn't get an advisory for split ball joint boots. I noticed them when I replaced my brakes earlier in the year and bought the parts. I mentioned it to them and said I've put the parts in the car in case it needs them. Nothing mentioned on the advisory list though.
If the Balljoints are anything but top and bottom there ok, but I certainly wouldn’t strip down to change a dust cover, new ball joints would be going in.
It was the top and bottom ball joints of the front axle. I bought 4 new Lemforder ball joints :)
Ah well, now I have them for when I need them. Can't be too long until they're worn with split boots. There has to be some amount of crud getting in there now.