Removing catalytic converter?

Submitted: Sunday, Dec 14, 2008 at 13:37

ThreadID: 64262 Views:8831 Replies:5 FollowUps:2

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Member - Drew T (Melbourne)

I understand that the catalytic converter on petrol 4WD is the part that is very hot and probably the initial cause of most 4WD fires (spinifex build up). Now while i clear out the spinifex several times a day if necessary I was wondering whether there is any merit in removing the catalytic converter completely for desert trips? (replace with a tailor made section of exhaust pipe?)

Actually on my last thru the Canning & Kimberleys I left the bash plates on becuase of the Kimberley section ... but next time i'll think i'll do the opposite as the amount of spinifex that gets under the bash plates is amazing (on one off-road section near the Canning I was checking & cleaning out spinifex every 20 min or so!!

DrewT

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Reply By: Member - Nick (TAS) - Sunday, Dec 14, 2008 at 14:00

Sunday, Dec 14, 2008 at 14:00

Have heard of people making up a straight through piece of pipe to replace the CAT on trips like your talking about, then replacing it when you get back.I guess its illegal but who is going to be able to tell anyway.

AnswerID: 339673

Follow Up By: awill4x4 - Sunday, Dec 14, 2008 at 14:18

Sunday, Dec 14, 2008 at 14:18

In Victoria it's a $10,000 fine if you get caught. The police are up to the old trick of a straight through pipe on the cat and will give it a tap to see if it gives off a tinny hollow sound to check it out. The smart guys who modify their cats fill the outer with clean dry sand so there's no noise if tapped.
Regards Andrew

FollowupID: 607192

Reply By: OzTroopy - Sunday, Dec 14, 2008 at 14:01

Sunday, Dec 14, 2008 at 14:01

The cat converter is a greeny / govt requirement on your vehicle in regard to the reduction of vehicle emissions. .... not of any vehicle engineering benefit whatsoever.

As such, it is a legal requirement (ADR I believe ) and the fact that it is a fire hazard is irrellevant.

Removal of the cat converter is normally made difficult by the fact that there is an O2 sensor "sniffing" the fumes at that point. Anything out of the ordinary will generally cause the computer to make changes to fuel delivery systems / timing electrics/electronics - higher fuel usage or breakdown.

Mind you .... a clever person with a couple of diodes could probably make the computer receive the correct voltage ( as if the O2 sensor was functioning correctly ) and everything would be hunky dory ... untill the RTA or whatever, had a look underneath and saw the cat' converter was missing.

AnswerID: 339674

Follow Up By: Tippa - Sunday, Dec 14, 2008 at 18:10

Sunday, Dec 14, 2008 at 18:10

Most cars have the 02 sensor just after the exhaust manifold, before the catalytic converter, although some have a second 02 sensor near the tailpipe (which can be disabed...).
Maybe the best way of stopping grass fires is to raise your car up a bit (more)... great excuse to convince the other half you need to "invest" a bit more money in the beast!

FollowupID: 607240

Reply By: Willem - Sunday, Dec 14, 2008 at 16:34

Sunday, Dec 14, 2008 at 16:34

Drew

What about covering the converter with some exhaust bandage? That should dissipate the heat.

When I buy a 4by I remove every conceivable bashplate and always watch where I drive :-) As a result there is very little collecting of spinifex stems or seeds underneath. The Nissan's first half of the exhaust has a protective jacket and this in turn keeps the exhaust heat inside the jacket to a degree.

Cheers

AnswerID: 339703

Reply By: RobAck - Sunday, Dec 14, 2008 at 17:49

Sunday, Dec 14, 2008 at 17:49

Bottom line is it is illegal to remove.

What is not understood is that all diesel engines, from 2005 also have catalytic converters. As well pretty much all now also have another device that catches the solids that come from the diesel combusion process and then burn them off if the vehicle is not operated at highway speeds on a regular basis. This applies to all diesel engines, 4WD or car that comply with Euro 4 and Euro 5 emission standards.

You will also most likely find that the engine management system will notice the cat is missing which could result in it changing engine settings but that I don't know.

So the issue not only applies to modern petrol 4WD but diesel ones as well.

Regards

RobA

AnswerID: 339715