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[jtp]

Failed Mot on emmisions. Will changing cat help to solve problem.
jeep has had a backfire on start up for years.

[YT]

My tester told me the cat was only a visual check, and made no difference to the emissions test itself.

[bgbazz]

  Is that right? I was always led to believe otherwise. Having said that..it might explain why most guys over here rod the guts out of the cat to help with the 'straight through' sound.

[YT]

Is that right? I was always led to believe otherwise. Having said that..it might explain why most guys over here rod the guts out of the cat to help with the 'straight through' sound.

I've had the insides removed from mine as it had started rattling and was buggin the excrement outta me. Didn't make a damned bit of difference to the sound. 
It was my usual tester done it

[daggie]

my guess is a sensor is fecked
probably pre cat o2 sensor

[isle of man]

my guess is a sensor is fecked
probably pre cat o2 sensor

I concur..And change the cap, plugs and leads to be double sure!!

[bigjeepzj]

 
also check for leaks in exhaust pre cat

[Mike Pavelin]

My tester told me the cat was only a visual check, and made no difference to the emissions test itself.

Bollocks. Yes, the CAT has to be present, but with no core it is unlikely to meet the required emissions standard. If the lambda and HC readings are well within limits, but the CO is too high (usually around 0.5) then the CAT is probably at fault. If the lambda reading is high, look for air leaks in the intake, exhaust leaks and upstream lambda sensor faults before condemning the cat. If all the readings are off, look for misfires, and general poor maintenance issues. 

[YT]

My tester told me the cat was only a visual check, and made no difference to the emissions test itself.

Bollocks. Yes, the CAT has to be present, but with no core it is unlikely to meet the required emissions standard. If the lambda and HC readings are well within limits, but the CO is too high (usually around 0.5) then the CAT is probably at fault. If the lambda reading is high, look for air leaks in the intake, exhaust leaks and upstream lambda sensor faults before condemning the cat. If all the readings are off, look for misfires, and general poor maintenance issues.

Well, ya live and learn. ) cheers for the clarification Mike. mines still passing emissions, so must all be good in the world of airborne nasties.

[Mike Pavelin]

You're either running LPG or your mate's fiddling the test results then.

[Dave69]

if cats don't do anything then they wouldn't be fitted.

Be wary of cheap replacement CATS as well, they certainly have less exotic materials inside and work less well than the more expensive, end of the day you get what you pay for.
How far out are the emissions ?

[Mike Pavelin]

Also, you're lucky if a cheapo one lasts from one MoT to the next.

[YT]

They do nothing for around the first half hour of every journey, or, the average commute. Also ever noticed, the majority of bikes don't have CATs fitted, and are exempt from the emissions test, yet they use the same fuel.
Some of the newer BMWs are fitted with cats, BUT, it's not compulsory.
The reason is very simple, bike engines are in a much higher state of tune, and burn fuel much more efficiently than cars of 4x4's, the do however still pump a known carcinogen (that was used to replace lead, and the same one that the yanks banned years ago) into the atmosphere the same as cars do, until the cat gets up to heat.
Unleaded being a 'green' fuel is a fallacy, it just doesn't contain lead, but the government/fuel companies won't mention that. There was a comprehensive write up on the whole thing in Performance Bikes magazine a while after they phased in unleaded, but for the most part, it's been kept very quiet.
The bottom line is, it's just another way to wring more money out of drivers.

[bgbazz]

Totally agree with you Phil...the worst part is that these questionable decisions are almost all made by idiots who don't or can't drive...but couldn't give a stuff if their chauffeur driven limo has a cat or not!!!

[Mike Pavelin]

BTW, as of last Monday, cats and DPFs on diesels must now be present for the MoT if originally fitted.

[bigjeepzj]

BTW, as of last Monday, cats and DPFs on diesels must now be present for the MoT if originally fitted.

so all these DPF removal people will lose out then

[bgbazz]

Really glad I don't live there any longer. It must be unpleasant to be forced to wear nappies all the time!

[Nosebolt]

BTW, as of last Monday, cats and DPFs on diesels must now be present for the MoT if originally fitted.

don't say anything about the other 364 days of the year 

[bgbazz]

That makes sense Bruce..have a 3 foot section of exhaust pipe with a cat and a dpf fitted...take it on or off whenever required.



Would probably last for many years.

[Mike Pavelin]

BTW, as of last Monday, cats and DPFs on diesels must now be present for the MoT if originally fitted.

so all these DPF removal people will lose out then

Nope, there are other solutions