Hi guys
As per the title. Our 1999 1.8 roadtser has been on the limit for the last two MOT tests fro CO emissions. lambda seems fine but fast idle test as been right on the limit. I cant really afford a new catalytic converter and the car runs really really well as it is.
It has a MAZDA speed back box fitted and a monster flow induction kit.
So will putting a dose of super unleaded high octane fuel help come MOT time? are there any other tricks that might help get it through the test?
Cheers
I suppose super unleaded would potentially help, but you might need to play around with the different types before you get the optimum - not ideal by any means.
Depending on how you use your car, a good run will potentially help the cat work more efficiently - if it spends its life pottering about time and not really getting hot, it can become chocked up, and work far less efficiently - a good drive that gets it nice and hot will help clear it out [Y].
A [B] or [G] has been known to (somehow) make a difference though… [A][;)]
How about trying a good dose of injector cleaner?
I’ve been pondering this, and it occurs to me if there were any significant difference between the injectors’ flowrates, you’d have some cylinders running leaner and some richer. The 02 sensor is bathed in exhaust flow from all the cylinders and will trim the fuel to match the average, so the lambda will be correct, but the rich cylinders will generate some CO and the lean ones will make more NOx.
Just an idea. I haven’t any figures.
Thanks guys
I have been pouring injector cleaner in a few times over the past month or so every couple of fill ups.
Was hoping it might have some affect. Also used a liquid called CATACLEAN available on ebay. I’m sure its snake oil but I thought it was worth a go as its cheaper than a new cat. it claims to clean the catalytic converter but I’m not convinced.
Was thinking come MOT time (very soon) I would fill up with super unleaded and also give it a dose of injector cleaner and cross my fingers.
I’m not friendly enough with any MOT inspectors to buy them a pint 
maybe its time I was LOL
Any other suggestions greatfully received. I dont think there is a mixture adjustment facility on these engines is there?
I know there was on our old Nissan primera.
I had similar problems to yours in 2006 so I used this stuff, I used it over 4 tanks full of petrol. The last two MOTs have not been a problem as far as the emmisions test is concerned. There are different bottles of similar stuff made by REDEX so make sure you get the one for Injectors. If your car is an Import make sure the MOT tester knows that, as it does make a difference
Thanks guys
i’m always up for a good blast so shall be hitting the red line a few times before it goes for its MOT LOL!
One more question, on using the Redex injector cleaner, is it better to empty and refill the tank with fresh fuel before the MOT or is it better to leave the injector cleaner in the tank while they do the emissions test?
Cheers
This may work on some cars and I did it on the advice of the garage, who supplied me with some additive to put in the petrol but unfortunately it didn’t work on mine. They did something that allowed it to just scrape thro the test but I believe they were testing it as a UK car not an import.
No need to empty the tank. I use it all the time now and I have never had any problems since I used the first bottle full over 4 tanks full of petrol. REDEX keep having special offers on the cleaner so I just keep my eyes open when I am near any of the many motorists shops and when it is on at a special price I buy 2 or 3 bottles .
I think that maybe they realised they had tested it as a Uk rather than a Eunos import model, but didn’t want to admit their mistake.
Is that a euphemism [;)]
Redline it a couple of times, but a sustained fast run will do it wonders - if you’re worried about points & fine, then do it in a lower gear… it’s about getting the engine, exhaust & cat hot for a sustained period (i.e. a good 5 miles+) - this will help burn off carbon, and give the cat a good clean through.