How to tell if I have precats?

[Paulprior]

Hi, before taking the Y piece off is there anyway to actually check if I still have precats in?

[Milky400]

Maybe infra red thermometer?

[Mr Plow]

Could you take the Lambda sensor out and stick a thin piece of wire through the hole and see if it gets stopped as you push it up through?

[bobfather]

You could remove one of the lambda sensors and poke a length of stiff wire in to see if there's any obstruction

[Paulprior]

I thought about the lamda sensor, but that's no so easy to remove without making a special tool, I was wondering about measuring the temperature as I have heard it will run a lot cooler, but what should the temperature be?

[ClassiChimi]

fking hot ,,,,, if it has pre cats that's not helping is it,,
If you had two cars side by side and tapped the manifolds on the one to be known to have pre cats then it might make a more muffled sound,,
I'd expect the removed pre cats to sound ,,, more empty, more tinnie

The other thing is you should expect more pops and bangs with the cats removed,,

If you can get access to the underneath or better still remove a front wheel you might see some outward dent marks on the underside of the manifold where someone's chisel or screw driver has gone through the honeycomb and made contact with the outer tin as there trying to smash out the pre cats.

There's only one way to be sure though and that's Y off and get your hands in there

I honestly feel my engine jumped alive a tad when removing pre cats,, faster, gases flowed out better so revved free,
Slightly louder but a nice sound of the exhaust gases moving rather than being muffled.

I then polished my original manifolds and Y piece back to silver,,,
Very interesting to see the colour change as the heat and speed of the gases hit corners etc,, what's very apparent by the consistent colour going on past the pre cats and down through my main cat is this light golden brown and slightly purple colouring,,, no restriction and it's a consistent temp,,, no hot spots,,
Engine bay is noticeably cooler and less tinks and pinks from the manifolds when cooling down,,

A couple of years ago,





As of a couple of weeks ago,,



I've been revving the engine on a few tracks,, the purple colouring has extended past the pre cats and can be seen on the bend before the Lambda's and Also on top the Y as it bends and goes on down towards the main cat.
Pre cats out

[Danblez]

Paulprior said:

I thought about the lamda sensor, but that's no so easy to remove without making a special tool, I was wondering about measuring the temperature as I have heard it will run a lot cooler, but what should the temperature be?

I measured mine a while ago and if I remember correctly tha manifold was close to 300 dropping to 270 just before the cat. The cat was about 250 and 230 just after.

I removed mine a couple of weeks ago and will measure again at the weekend for you.

Personally I would just buy a cheap 17mm deep socket and cut a slit with and angle grinder then whip a lambda out as it's useful to have one at hand anyway!

[Belle427]

A cranked ring spanner may fit the lambda sensor, the dedicated sockets are not that good anyway, especially the cheaper ones.