MOT failure

Hi All,

I have had my P38 in storage for nearly two years due to what I thought was an issue with a piston misfire but turns out to be plugs/leads! Don't even go there!!!

Oddly enough the car actually passed on everything else but failed on emissions which came as a surprise - 25% over the legal limit!!!! I had the lamda sensor replaced for a similar reason a few years back but at 17yrs old wouldn't expect the old girl to be running perfectly. That said, she passed an MOT back on 2011 without any issue and hasn't been running much since.

Any ideas as to the problem? It isn't worth forking out £££ for catalytic converters as I have an L322 which is in perfect condition but still don't want to let the P38 die either. All help/suggestions appreciated. I thought maybe fuel/2yr old oil could be an issue since it has been standing a while but marginal difference to the readings apparently so I need a cheap but sensible solution in an ideal world.

Thanks.

Fuel is only really good for a few weeks, after that it gets crappy...

Did you take it for a good few hundred mile burn to clear out any crap before hand??

Cats work optimally when warm, and sitting for a couple of years with spiders and moisture etc crawling in them will take a while to clean out and operate efficently...

Old Plugs will create an uneven burn....old oil etc....

Good idea to give it a thorough service...

Good service load her to the hill with bricks and a trailer find the biggest hill you can and have it labouring for a good bit 100% load will burn it clean

Roughly 45mph for 15 minutes in third gear is how long it takes for a cat to turn on.

Vauxhall Vectra will cruise in third at 70 for 30 minutes in third or fourth to burn out crude in a DPF (that was the official "fix" given to our garage by a local Vauxhall dealer).

So burn it clean. Most garages will thrash the nuts off of a car for a bit to pass an emissions test as too many vehicles are only used around town in light duty. You need to get heat into your exhaust to make it run efficiently, otherwise it just creates restrictions that do nothing to help clean the air.

Put new fuel in put new filter on ,put new oil in put new filter on !!!!
Fetch the mice out of your air box!
Take it a good thrash , then go mot again !!!!
If emissions are still high then further investigation is needed !! Check all hoses vacuum pipes etc !!! Good luck !!

Put a fuel cleaner through it, £3 at ASDA! Clean plugs or replace, whip out air filter for test!!!

Or you could get it on testbook or similar and see what is going on,the Cats light up quickly in seconds rather than 15 mins with hot gases going through them.Fuel does lose some of its goodness,but not all - I had a car recently fly through emissions test after sitting for 3 years with the same fuel in it.

Many thanks chaps very helpful thank you

Dint think fuel gets old ive got a capri that my dad left and the fuel thats in it is about 8years old
Still starts and runs on first turn of key (after ive put a jump lead on it)

gfromleeds said:

Dint think fuel gets old ive got a capri that my dad left and the fuel thats in it is about 8years old
Still starts and runs on first turn of key (after ive put a jump lead on it)

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It'll still work, but will be beyond its best....

The additives they put in to clean, protect, burn more efficently etc will be broken down and useless, so the fuel won't burn cleanly or efficiently....

So yes while the engine will run on it, it won't be very efficent or clean!

Saint.V8 said:

It'll still work, but will be beyond its best....

The additives they put in to clean, protect, burn more efficently etc will be broken down and useless, so the fuel won't burn cleanly or efficiently....

So yes while the engine will run on it, it won't be very efficent or clean!

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It's an oft quoted thing about petrol, I wonder how true it is? My MR2 was laid up for 10 years with close to a full tank of petrol. Started first time when I put a new battery on, no noticeable difference in performance and passed it's MOT with no comment on emissions

Datatek said:

It's an off quoted thing about petrol, I wonder how true it is? My MR2 was laid up for 10 years with close to a full tank of petrol. Started first time when I put a new battery on, no noticeable difference in performance and passed it's MOT with no comment on emissions

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Not being in the PetroChem industry...my only research is from internet and word of mouth...

Real world examples such as yours and GFL's are more reliable information...and I know stand corrected and learned....

Next time the subject is raised I can now speak from real world reference that old petrol is a viable Hydrocarbon and as such should still burn clean....

Saint.V8 said:

Not being in the PetroChem industry...my only research is from internet and word of mouth...

Real world examples such as yours and GFL's are more reliable information...and I know stand corrected and learned....

Next time the subject is raised I can now speak from real world reference that old petrol is a viable Hydrocarbon and as such should still burn clean....

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I'm absolutely not saying you are wrong Ant, I just wonder how critical it is.
The MR2 is pretty highly tuned, so anti knock additives would be conspicuous by their absence if they disappeared.

Well my 1956 Ariel HT5 has been sat for 10 months and started second kick after a gearbox rebuild. I'm not saying either that nothing is lost from the petrol - just that it cant be that bad.My little Suzuki Alto's emissions were absolutely perfect with 3 year old petrol and its performance is mind blowing.....

Latest is, new fuel/additives didn't work!

Next idea? New CATS? Yikes!!

Did you give it a good burn around to clean the carbon deposits out...clean engine oil...could be sticky valve tappets....Clean Air Filter...Clean the MAF etc etc etc

Datatek said:

It's an oft quoted thing about petrol, I wonder how true it is? My MR2 was laid up for 10 years with close to a full tank of petrol. Started first time when I put a new battery on, no noticeable difference in performance and passed it's MOT with no comment on emissions

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I think anybody would be pleased but you were lucky to have encountered such an open-minded tester.

G~

Martin1_01 said:

Latest is, new fuel/additives didn't work!

Next idea? New CATS? Yikes!!

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No, absolutely not ! Why not get it checked out properly to see whats going on ? I've sorted emissions failures on P38's in the past by just changing one s/h plug lead for tight sales mobs - they wouldnt even pay for a new set.
P38 v8's pass cats tests with ease if they are running properly,and 99% of the time its very quick and easy to find out whats wrong.A quick code read followed by a live data session usually shows up the problem,sometimes a scope session around the HT leads is necessary.
Any decent LR independant should do this for a reasonable sum.

gencybay said:

I think anybody would be pleased but you were lucky to have encountered such an open-minded tester.

G~

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The emissions were all in spec, I was watching over his shoulder and he did not know that the car had 10 year old fuel