Topic

Hi all I am in need of some advice please. Last year my local garage put a new (bog standard) exhaust, cat and lambda sensor. The car then failed it's mot at first then passed on 2nd attempt. 1st time in 7 years it failed on emmisionnsAnd now it's failed again on emmisionns. I am at a complete loss on what to do next any advice suggestions appreciated.I added cataclean and gave it a good run prior to the test.

I find the best way to reduce emissions is to eat less fibre………oh you mean the car!

I’ve never had to bother with emissions test nonsense, here in Victoria the best state of Australia, we don’t have annual tests, it’s only when a car changes hands does it require a RWC (road worthy certificate) even then there is no emissions test.

And before anyone starts banging on about safety, some other states require annual RWCs and they have much the same accident per capita and per mileage rates, which is proof to me that annual inspections are a cash grab for the workshops and little else.
I’m not the only one who sees this.
Every few years the VACC ( Victorian Automobile Chamber of Commerce) kicks up a stink to try and get the government to bring in annual inspections and the politically powerful and cash rich RACV (Royal Automobile Club of Victoria) arcs up and won’t have a bar of it!
So the vested interests of the car dealers and repairers retreat to lick their wounds.

Do you have a after market exhaust or cat fitted? These can sometimes cause problems.
If everything is standard, then I would recommend a "Italian tune up" that basically means giving it a good thrashing prior to the next emission test.

By the time I get to the MOT station everything is up to spit sizzling temperatures. I take myself on a right revvy run, up to the end of the M65 & back. It’s a trip always marred by poor driving etiquette, bad manners & German cars trying to get into your boot whilst you’re doing very nicely thank you. And when you pull in to let them pass it’s like the space race; they all race to occupy the space you have just vacated. I digress.
M

You said it passed on the 2nd attempt for the last MOT. What work was carried out between the first and second attempts ?
Do you know the last time the spark plugs and air filter were replaced ?

The garage added some fuel cleaner and took the car on a run I presume to get the cat hot. And seem to remember something about fuel trim, but I will check that. Spark plugs were changed about 18 moths ago. As I say had no problems prior to the new exhaust and cat . I will buy a OE cat if it's going to get through the MOT.

This is of no help to the OP but I've often wondered if Kmaps and the like can remap an ECU for a bit more power etc surely they could remap one to run very lean and get thru the emissions test. This would not be suitable for normal road use so would involve swapping out when needed, some might consider this expensive but often on the forums people have changed plus, leads, coil packs and then start on o2 sensors etc and still they fail.
Perhaps those with the skills and knowledge could comment as to the viability of this option.

To be honest, 99% of fails are due to fitting cheap catalytic converters...

You are correct, but even cheap cats can be coaxed through if they are given a good hot run, you won't get many passes with them though. Traffic these days mitigates against such a run, I always book my car in for the first test of the day, there's always a car on the ramp, so by the time I'm on the rollers Dave's had enough coffee to be on the button. And that's at 8-00. 7-30 would in the passed see me one junction up & back to present at 8-00, that's all but impossible these days with the traffic. Now my trip is all rev's & medium speed. It's a good many years since an emissions failure.
M

Thanks all for the advice, after a 30 mile Italian tune up the car passed

Great news..enjoy 👍