cats

Yeah, provided that it didn't make too much noise (the car afterwards, not the removing process) and provided that it didn't mean the car would be illegal to drive on the road.

Contrary to popular belief it 's not illegal to remove the cat. It's just that you'll probably have trouble passing the post 1992 MoT emissions test without it.

I drive a diesel car at the moment and that has a particle filter as well. Which is coming off and being replaced with straight pipe next time it requires replacing. Just have to fiddle with the ECU code to get it to ignore the pressure sensors.
 
i put a decat on my civic and yeah it sharpened up the throttle response but didnt feel like it had gave much power.
sports cats seem to be the best compromise bit more pricey than a decat but at least then you dont need to swap back to the original cat for the Mot, unless you have a friendly tester who will use another car.

Hdi will removing the particle filter not cause more smoking ?
 
If you remove the cat and the remap the ECU so that it no longer has to obey the 14.7:1 stoichiometric air:fuel ratio (by mass) then you can get some superb gains in fuel economy, quite apart from the performance hike.

Cats killed lean burn technology overnight. Twenty years of industry research wasted.
 
HDi fun said:
If you remove the cat and the remap the ECU so that it no longer has to obey the 14.7:1 stoichiometric air:fuel ratio (by mass) then you can get some superb gains in fuel economy, quite apart from the performance hike.

Cats killed lean burn technology overnight. Twenty years of industry research wasted.
Click to expand...

Worth doing do you think?
Thanks
 
"HDi will removing the particle filter not cause more smoking."

Yes, it will, without doubt.

But my car does not need to meet the Euro IV regs (even though it does with the PF) by law.

So it can bloody well smoke its little head off as far as I'm concerned. VOSA and all the other self appointed roadside emissions experts can go and swivel.

Right - that's better ;)
 
Basically, you're not going to get masses more power or torque simply by taking off the CAT(s). There will be a little less back pressure so a slight yield at the top end of the rev range. THe same might give you a slight increase in fuel economy.

But the O2 sensor and ECU will be controlling the fuelling to keep within the boundaries required by the cat to avoid either poisoning it (too rich) or burning it (too weak).

With the cat out of the way you can approach a good tuner to remap your ECU to remove these now unrequired constraints. The problem is that you probably won't get through an MoT test without the cat. And putting it back on for the test won't work because of the new fuel/igntion map.

Superchips do a product called Bluefin which allows you to change maps on the fly. It may well suit your needs.
 
HDi fun said:
Basically, you're not going to get masses more power or torque simply by taking off the CAT(s). There will be a little less back pressure so a slight yield at the top end of the rev range. THe same might give you a slight increase in fuel economy.

But the O2 sensor and ECU will be controlling the fuelling to keep within the boundaries required by the cat to avoid either poisoning it (too rich) or burning it (too weak).

With the cat out of the way you can approach a good tuner to remap your ECU to remove these now unrequired constraints. The problem is that you probably won't get through an MoT test without the cat. And putting it back on for the test won't work because of the new fuel/igntion map.

Superchips do a product called Bluefin which allows you to change maps

on the fly. It may well suit your needs.
Click to expand...

maybe best doing that, will check out superchips, thanks for your help
 
so if you remove the cat you dont pass the MOT?

therefore its not legal for you to drive your car

so how comes so many people do it?

im confused :confused:
 
TITAN said:
so if you remove the cat you dont pass the MOT?

therefore its not legal for you to drive your car

so how comes so many people do it?

im confused :confused:
Click to expand...

Not quite. There's no requirement whatsoever for a car in the UK to be fitted with a catalytic converter. However, it's unlikely that it'll pass the UK MoT emissions test without it being in place and working correctly; also, the supporting infrastructure (lambda sensors, MAF and everything else) will need to work correctly for this to be the case.

WE need to be careful here. It's not necessarily illegal, but is probably unlawful. Further, it's possible to find yourself on the wrong side of the law for doing something unlawful. It doesn't have to be illegal for you to be challenged.

If you can get your car through the MoT test without a CAT then you are at liberty to drive it around without one (a cat, not a valid MoT test certificate). And if it passes the Mot without the cat then the roadside emissions lot will never stop you on account of visible emissions because if there were any (visible emissions) the MoT test would have been aborted immediately.

You have to be careful because removing the cat constitutes a vehicle modification. And your insurers might see fit to void your policy if you had occasion to make a claim upon it if you had not disclosed such a modification. Again this does not mean that you are using your car illegally, although you are possibly using it unlawfully.

It's a dark grey area. But if your insurer decided to void your policy on account of undisclosed Modifications in the event of a RTA then you will be found guilty of the offence (illegal this time) of driving without adequate insurance should your insurer elect to decline a claim.

THe best thing you can do is discuss your plans with your insurer and gain agreement IN WRITING that your policy is valid. You need to get it written into the policy schedule and make certain the the certificate of motor insurance refers to that that schedule specific to your policy.

it's strange that we need to go this far with a midified car because insurers will happily pay out for an accident caused by a druken policy holder.

That's BRitish law for you. Unpredicatable at best. Unreliable at worst.
 
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youve got to remember that having an MOT certificate doesnt mean that the cars fit to drive as well. Like Hdi said on a roadside inspection you may find the cars not fit to drive, in the same way as you might have a MOT dated 2 weeks ago but sine then your tyres are now bald so therefore illegal because of this.

the problem is that too many people know someone that is a tester and so can get away with a decat, come mot time the probes stuck up another car to pass and a MOT certificate is issued
 
pgarner said:
youve got to remember that having an MOT certificate doesnt mean that the cars fit to drive as well. Like Hdi said on a roadside inspection you may find the cars not fit to drive, in the same way as you might have a MOT dated 2 weeks ago but sine then your tyres are now bald so therefore illegal because of this.

the problem is that too many people know someone that is a tester and so can get away with a decat, come mot time the probes stuck up another car to pass and a MOT certificate is issued
Click to expand...

It's common. But folks that take interest in and responsibility for their respective cars are possibly thinking and thoughtful drivers. So what harm does another couple of g/Km do? I'm not sure that global warming is an issue anyway.

Seems to me that it's a convenient way to apply stealth tax.
 
A sports cat gives the same benefit as a de-cat and keep the cars emissions within tolerances. Admittedly a decat is cheaper but if you cat needs replacing a sports cat is usually about the same as an OEM one. ;)
 
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