unexpected mot fail

H

houston

my car failed its mot on brake pipes, emissions and a one that i had no clue about, missing wheel nuts! some thieving git has pinched 3 of me wheel nuts! i needed to get some locking ones anyway but what a liberty!


now for the help bit, 0.3 is the max for co2, mine got 0.58, plugs are new, oil was done bout 4 month ago, put injector cleaner in, only thing i can think of thats left is the cat, anyone else know of owt i havent thought of?
 
Have you got a cat or has it been removed? Is it definitely the CO2 reading that's high or is it the CO reading? Also, has your timing been advanced?

Some stuff here on CO...

High CO is caused by a rich air/fuel mixture. The air fuel ratio should be 14.7 parts air to to 1 part fuel. Problems that can cause a rich mixture include:

* Problems with the feedback system (the system that regulates the fuel being added to the engine based on the amount of oxygen in the exhaust).
* Problems with a computer sensor such as the coolant temperature sensor, air flow meter, MAP sensor, etc..
* Problems with the fuel pressure. Fuel pressure that is too high can cause a rich mixture.
 
its got a cat, but dunno if the timings been advanced, didnt think it was doable without a piggyback ecu, the coolant temp sensor is deffo ok cos its new, but could be maf, cars costin me a small fortune in petrol, get jus under 50 mile to 10 quid of petrol.

i put some injector cleaner in and gave it a good blast down the a19 so engine was at a good temp for test.

another strange bit, the engine management light came on not long ago, quickly checked code n it came back wit 0420 again! this came up a few month ago but went off on its own, think its to do wit the cat but dont understand the code description TW CATALYST SYS
 
three way catalyst (Manifold) is the cat in the manifold?

Exhaust tube - exhausts fine but it does have an aftermarket tail pipe, shouldnt affect it tho if theres no leaks

Intake air leaks - gonna check in mornin but dont hear any induction whistle when driving

no petrol leaks and spark plugs are new, how can i check the timing?
 
were they not knocking though? i sheared one on my old car and gave me no end of grief, ended up costing £400 trade to get sorted :mad:
 
try a fuel treatment and a new CAT, give it a good blast for 15min's before the test and it should pass.

car would drive fine without 1 nut on each wheel (some car's only have 3 ie. old saxo's), if you have steal wheel's, put some wheel trim's over them and its an MOT pass without even replacing the nut's. If you have alloy's you will need new wheel nut's

also the fault code you gave 0420 isn't a complete fault code, but i can tell you it has something to do with your CAT not functioning properly. Either it's totally nackered or its storage capacity is very low. Could also be related to your o2 sensor i suppose.

Do you have a high flow exhaust system on your car (i.e bigger diametre), if so, this is probably the cause of the code.
 
yup its got a 3 inch tailpipe! its been in garage to get brake pipes done today, i had a look n saw they go over fuel tank n jus thought fuk it!

im good mates with the garage owner n he got onto his mate bout the fault code, apparently nissan cats are really good n hardly ever need replacing, he told me its most likely the pre cat lambda (o2sensor) which needs changing, this is the one that controls the fuelling, the post cat sensor is a monitoring probe which throws the fault code.

so 60 quid lighter for a new sensor now n we'll see next week if it passes mot!

also when it was up on the ramps me mate says hes surprised they didnt say owt about the crossmember, looks like its in a sorry state, rust holes are appearing so doesnt look good for next years mot!
 
I was gonna say how'd you not notice the missing nuts- but I suppose it's not something you look at every time you get in and out of the car.

Houston_we_have_a_problem_small.jpg
 
car was at right temp, had put injector cleaner in and took it for a trip at 60mph in 3rd gear.

hoping its the 02 sensor, dont fancy forking out for a new cat.

the wheel nuts were there when i did the brakes, only thing has to be they were stolen
 
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