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how can you tell a cat's dead ??
samjc - 20/4/12 at 08:11 AM

Hello all.
ok this isn't about the living meowing type so not to worry those animal lovers :-)

Ok well my daily driver (ford fiesta 2003 mk6) is up for sale but before it goes i want to make sure it's all ok as i try to sell as if i were intending to buy. but more to the point lately its been realy sluggish and the engine management lights cropped up. had it reset and again its back. fault reads lower lambada sensor fault.
mot station say the cats dead go buy a new one so went to the local exhaust place were the mechanic asked for a look before ordering and booking anything. well hes said it doesn't smell like it, car doesnt seem restricted when reved so hes sugesting sensor but to run an emisions test first incase.

What else can i try to do?
what are the tell tale signs of a dead cat??

sprouts-car - 20/4/12 at 08:24 AM

If you don't observe it then it wont be dead or alive.

MkIndy7 - 20/4/12 at 08:28 AM

When you call it for its tea and I'd doesn't come in?

I've not much of an idea about CAT's I'm afraid but there's a product called something like Cataclean thats supposed to be really good..
Or if you belive its just a sencor fault you could swap the upper and lower sencors IF their the same and see if the fault follows.

Macbeast - 20/4/12 at 08:49 AM

If you don't observe it then it wont be dead or alive.

No - it will be BOTH dead and alive

sprouts-car - 20/4/12 at 08:53 AM

quote:
Originally posted by Macbeast
If you don't observe it then it wont be dead or alive.

No - it will be BOTH dead and alive


Exactly.





(p.s. I seem to have hijacked this from the original question

[Edited on 20/4/12 by sprouts-car]

steve m - 20/4/12 at 09:43 AM

My old Rover 75 1.8 k series had the eml light on and off for years, and at mot time the tester had to coax the car through the test, and it only just got through
yet once i changed the lamba (about £30) it was a different car and sailed through its last mot while in my care!

Not sure if its true, but a headgasket failure (i had two) mucks the lamba up, so a new one was required

steve

steve m - 20/4/12 at 09:46 AM

Also, with the car at a normal hot temp, engine running the exhaust fumes smell like an eggy fart, and if it does, the cat is working

[Edited on 20/4/12 by steve m]

UncleFista - 20/4/12 at 10:24 AM

An emissions test at a friendly MOT station ?

stevebubs - 20/4/12 at 10:40 AM

I would always suspect Lambda sensor over cat..

Norfolkluegojnr - 20/4/12 at 10:47 AM

coyoteboy - 20/4/12 at 11:05 AM

quote:
Also, with the car at a normal hot temp, engine running the exhaust fumes smell like an eggy fart, and if it does, the cat is working


My other half's car doesn't smell eggy at all and it's cat is working fine. My car smelled fine before the cat was removed also.

Edited to include some good info!

"As the fuel burns, the organic sulfur compounds break down into simpler compounds. If the engine is running lean (more air than is needed to burn the fuel), the sulfur is likely to be SO2, or sulfur dioxide. The catalytic converter can change this into SO3 (sulfur trioxide), which then reacts with the catalyst to form sulfates on the catalyst. Over several minutes there is a build up of sulfates. If the engine suddenly starts to run rich (not enough air to burn all the fuel), such as when you stop at a red light, climb a steep hill, or brake hard to slow down, the chemistry changes. Now the sulfates are unstable and they react to form hydrogen sulfide, which is expelled from the exhaust pipe all at once. The high concentration is the reason for the bad smell! This effect is a common problem with new vehicles because the catalyst is working at a very high efficiency. However, as the catalyst gets older, the activity drops. Fortunately for us, one of the first reactions to be affected is the formation of hydrogen sulfide. So as the catalyst gets older, the smell will go away. It should also be noted that many catalysts never smell bad. One reason might be because the vehicle doesn't run lean for much of the time, or perhaps the catalyst has an extra component that reduces the production of hydrogen sulfide.

"Next time Eggbert and Shelley stop behind a vehicle that smells bad, they can be grateful that it's at least not contributing much to atmospheric pollution."

Thanks to this month's Whizard, Dr. Gordon Bartley, a senior research scientist in the Emissions Research Department of the Automotive Products and Emissions Research Division. Bartley specializes in the development, aging, and evaluation of vehicle emission catalysts.




[Edited on 20/4/12 by coyoteboy]

snapper - 20/4/12 at 11:54 AM

quote:

fault reads lower lambada sensor fault.


Am I missing something?

"My fault code reader says "low oil pressure" so I changed the rear wheel"

I think I would check the lambda first, it's cheaper than a cat

britishtrident - 20/4/12 at 04:57 PM

First thing is to find out if the engine is running closed loop and what signals are look coming from both hego sensors. The other thing is to make sure the engine is running hot enough.

The voltage output from the sensors can be checked by making a tap connection into the wiring but checking by reading OBDII live data is easier although it it won't show a sensor out of calibration.

[Edited on 20/4/12 by britishtrident]