Removing Catalytic Conv. and 2nd O2 Sensor

Anonymous · October 10, 2003, 14:42

HI Everyone,

I like to up my performance by installing a custom exhaust, but the cats will get romeved completely. How will this affect the 2nd O2 sensor, the one after the CAT. Doesn't this sensor ensure the Cat is performing its work, and if not the ECU tries to correct it. This means without a CAT the performance will degrade since the ECU will try and ensure the CAT work due to the 2nd O2 sensor.

Any views on this theory, no CAT and 2nd O2 sensor

markiii · October 10, 2003, 15:37

if the cat is detected as faulty by the 3rd 02 sensor There are 2 in the manifold) then there is nothing the ECU can do about it apart from flag the light so you can get it fixed. So no performance shouldn't drop

however whether performance will increase is also debateable as back pressure is beneficial to a certain extent on an NA engine. If you wait a while mine is being done soon so I shall dyno it and see if there is a benefit or not.

If you did it you would need an 02 simulator to eliminate the check light.

you can remove the cats in the manifold no problem as long as you keep the 1st 2 02 sensors in teh correct place.

Anonymous · October 13, 2003, 06:15

Hey Markiii

Thanx for the explanation, 2 no make it 3 further queries..

What does the O2 simulator do and where can I get one?
Did you get a performance increase?

markiii · October 13, 2003, 08:09

the 02 simulator gives the sensor the reading ti thinks it should get so that yu don 't get a check light due to having no cat. Try w www.PPeengineering.com w mph and I both got ours fro Paul there.

did it work? no idea as it's not done yet, I'll let yu know.

Anonymous · October 13, 2003, 13:53

Markiii, Thanx, will be waiting in anticipation s:lol: :lol: s:lol:

Jap GT300 · October 17, 2003, 16:17

Mark

You should have come to see my setup at Santa Pod. I've got sraight through off the block (N/A) running 1 O2 sensor.

Its loud as ****

markiii · October 17, 2003, 16:21

thats going to be the test,

sound aside what gains do I get? and with the main cat back in?

If the gains are high enough I may just have a little extra silencing put in.

Jap GT300 · October 17, 2003, 16:22

p.s. I've had mass engine light problems. It's chucking out all sorts of codes. Even when I was just running with just no main CAT I couldn't get it to settle. Also the idle is rough, it sits quite a bit lower.

I'm pushing 161hp at the moment, but should be getting quite a bit more. I'm waiting to see if I can get a refund on my Dastek, then i will see if i can get the power pushed up! I am aiming for 170hp.

Adam

Jap GT300 · October 17, 2003, 16:52

Manifold gives about 6hp and decat gives about 4hp

markiii · October 17, 2003, 16:55

it's tuning dependant not the dastek. If milway can get an extra 20 out of a stock engine, then I'm going to be using them. Plus I'm going for a H&S 421 equal lentgth manifold, so I'm hoping to improve on Pauls results.

Jap GT300 · October 17, 2003, 17:19

I only had 1 dyno under tuning with the Dastek. I'm trying to get a refund so that I can go to millway with it.
I also didn't follow it through because I didn't have the flywheel, hks plugs, grounding kit or 330 injectors installed (the injectors are now no longer going on)

I should get 170 by the time I've finished. I've also lost loads of weight!

With the same setup, someone on SC is claiming to get 182!

Adam

markiii · October 17, 2003, 17:27

grounding kit? not convinced personally.

Anonymous · October 19, 2003, 11:20

Markii,

Whats the score with the H&S 4-2-1 exhaust manifold - when's it available and what sort of price are we talking? I'm seriously interested in one. If there's aver a group buy let me know. s:D

s:D

Anonymous · January 30, 2004, 12:23

have been reading this old thread with interest in regards to the 02 simulators, what wa the outcome with these did they do the job and settle the eCU and put the light out correctly when the main cat was removed/gutted?

markiii · January 30, 2004, 12:31

Perry,

I've not installed my simulator yet, though strangley after clearing teh last check light some 1000 miles ago it hasn't come back on. This is strange but I'm not knocking it.

Do they work, yes as MPH has had his in since going turbo.

And before anyone asks me about the manifold, I've not taken tis any further yet. There is a very nice piece of kit being made by PPE in teh US which I will probbaly go for if I go tis route. I'm just debating if NA will give me the power and useability I want or fi I shoudl go turbo.

Anonymous · January 30, 2004, 12:37

Thanks mark :-) :-) :-)

had a look on the PPE site but couldnt find it? was it actually detailed on the site when you bought yours?

markiii · January 30, 2004, 12:45

Perry,

It's techncially something Paul includes as part of his downpipe package. I don't beleive its listed individually.

having said which if you email Paul I'm sure he'll sell you one seperately, I beleive I paid around $15.

Anonymous · January 30, 2004, 13:42

Thanks Mark thats great :-) :-) :-)

so just to re-cap, as far as I understand it you can gut you two pre-cats without any need for a box of tricks to trick the ECU, but if you gut the main cat then this is the daddy?

has anyone your aware off done all three? as I am also concerned regarding back pressure issues?

mph · January 30, 2004, 13:43

Note the difference between 'conditioners' and 'simulators'. I have a conditioner in mine - it works 95% but occasionally throws up a CEL, usually if I'm going through a town with lots of stop-start dashes.

markiii · January 30, 2004, 13:45

Which I beleive you got from PPE? which means it's the same as mine.

So mines a conditioner as well. I must stop using teh terms interchangeably.

Tem · January 30, 2004, 14:09

Quote from: "mph"Note the difference between 'conditioners' and 'simulators'.

So what is the difference...? I always thought it's just another UK/US thing, with two words for same thing s:oops: :oops: s:oops:

markiii · January 30, 2004, 14:13

STRICTLY speaking;

A conditioner takes a signal and does something with it, for example if the voltage range of a variable signal was too low due to some mod. In order to keep something else happy you could amplify it, thus conditioning the original signal to a form that makes sense to something else.

A simulator? For example (I'm not saying it works this way) lets say the 3rd 03 puts out a known signal to indicate that the cat is working. And when the cat isn't working puts out nothing. We may simulate this by putting something in place to generate from scratch teh signal that is expected.

A conditioner is better where the signal depends upon a variable such as engine speed, which sinc it isn't constant you an't just fake.

l

Tem · January 30, 2004, 14:19

Thanks mark, I thought they were all just simulators that put out some constant voltage...

Anonymous · January 30, 2004, 16:47

What a helpfull guy Paul at PPE is :-) :-) :-)

in stock , being sent out today $15.81 inc P+P and paypal %

sound as a pound s:wink: :wink: s:wink:

markiii · January 30, 2004, 16:49

yeah Pauls a good bloke.