Decat a 6A1

[bonesthebutcher]

Since switching to Shell V-Power I've noticed my exhaust tone is not so fruity as it was with "standard" super-unleaded. Certainly the engine seems happier, quieter, smoother, but I no longer get the addictive tone under acceleration that I used to. So... I was thinking a decat would restore the fruity tone, and perhaps give a minor performance boost to boot

Only problem I can see is the Mitsi service manual shows lambda sensors both before and after the cat. I'm guessing if I don't do anything about the post-cat sensor the engine management light will turn on and the car will run in some sort of "non-optimal" mode?

Is there a way to fool the post-cat lamda sensor into reporting "all okay"?

[AlanDITD]

Just fit it, you wont get any problems afaik!

[crazydriver81]

if you have an O2 sensor behind the cat, you will get problems with the CEL (check engine light).

In this case, you have to look for a method to fix the OBD CEL...this is common amongst our Evo owners out there

http://www.lancershop.com/customer/p...productid=1259

There are also electronic devices to "simulate" the second O2 sensor. Give google a try...

[bonesthebutcher]

if you have an O2 sensor behind the cat, you will get problems with the CEL (check engine light).

In this case, you have to look for a method to fix the OBD CEL...this is common amongst our Evo owners out there

http://www.lancershop.com/customer/p...productid=1259

There are also electronic devices to "simulate" the second O2 sensor. Give google a try...

Thanks for the info. I'm off now on a google, ebay, and lancershop shopping hunt

[bradc]

I thought that Kieran said that you could fit a decat and the car didn't get angry with you. Perhaps send him a pm?

[Kieran]

I thought that Kieran said that you could fit a decat and the car didn't get angry with you. Perhaps send him a pm?

I certainly did that to Hordak (Late 2000 V6 Sport) and he was perfectly happy. No issues, no CEL.

[bonesthebutcher]

I certainly did that to Hordak (Late 2000 V6 Sport) and he was perfectly happy. No issues, no CEL.

Great news! I'll get a decat pipe on order straight away and if I'm unfortunate enough to get a CEL, I now know what's availiable to fix it

[fuel]

I'm pretty sure the sensor after the cat converter is the temp sensor for the cat converter for when/if it overheats. That's why you see a cat converter warning lamp everytime you start the car. If you simply unplug it the cat converter lamp will remain on, I think if you ground the connection it thinks it is running at optimal temp.

[Kieran]

I'm pretty sure the sensor after the cat converter is the temp sensor for the cat converter for when/if it overheats. That's why you see a cat converter warning lamp everytime you start the car. If you simply unplug it the cat converter lamp will remain on, I think if you ground the connection it thinks it is running at optimal temp.

That was the case for cars like the FTO and such, but in the UK the 2 sensors are Lambda sensors - There's no 'Cat Overheat' warning lamp. They're needed to conform with the EURO-II/III emissions regs which mandate a cat must be fitted and a feedback system should be used to ensure it's working correctly.

Quite why they don't fault-code when you de-cat them, I'm not sure.

[bradc]

More importantly, from the seat-of-the-pants-o-meter, how much extra power does it feel like you get?

[Kieran]

More importantly, from the seat-of-the-pants-o-meter, how much extra power does it feel like you get?

Not much difference at all in 'pull', though the engine feels much more free revving, and perhaps a little less pegged back at high RPM. The main bonus is the added music - and as you know, the 6A13 N/A sounds glorious to start with

[bradc]

Indeed, I've had the ST-R for a good few years now with a stock setup but a different back box - not a performance one at all, just a generic standard muffler and it sounds great. I'm moving to a decat and a Ralliart tip for my new 2000 ST-R and I can't wait!

[Kieran]

...I'm moving to a decat and a Ralliart tip for my new 2000 ST-R and I can't wait!

Just the tip, or do you mean a standard 'Ralliart' backbox?

[bradc]

I'll show you pics when the car is done. It isn't the standard muffler on VR-4's but is a bit smaller. It still looks like a stock muffler from some car though! The Ralliart tip looks like it was factory welded on though and fits fine.