Running exhaust system without pre-cats

[Bonzo1 Lurker Find all posts View Profile Close Bonzo1]

I recently acquired some pacemaker headers and a 2.5" pacemaker system with high flow cats and am getting it installed in a few weeks (after I grind the rust off and coat it in some header paint).

My concern is that the pre- cats (the ones that sit just after the headers and the fuel/air flow sensors I believe) are absent and I'm wondering if I will have any trouble with this in regard to throwing up an engine light.

As far as I've read I hopefully shouldn't have any problems with passing emissions tests if the car is warm when tested and the need for an emissions test.... arises 😆.

Is anyone running a system like this/can offer me some advice?

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Yes it will throw a number of engine light TC's. And in turn will shut down VSC, traction control and ESC. ( known in Toyota terms as the Christmas tree lights).

Urban legend says a hot car will pass emissions, but a lot fail too.

[Bonzo1 Lurker Find all posts View Profile Close Bonzo1]

Yes it will throw a number of engine light TC's. And in turn will shut down VSC, traction control and ESC. ( known in Toyota terms as the Christmas tree lights).

Okay, right... But I fail to see why it would shut down those systems considering they're completely unrelated? (unless that was sarcasm, which doesn't translate well over the internet &#128517.

That being said, after reading a few things I'm a bit worried that I've been sold a system without cats and with pre cats still in place, rather than a system with high flow cats and no pre-cats... Can anyone confirm the location of the cats for me?

Here is my system: https://www.dropbox.com/s/4aiixuaogu...01-48.png?dl=0

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Running exhaust system without pre-cats

Those systems will shut down. It's not sarcasm.
Here's a preview of what you can expect when the xmas tree light arrives.

[clarkie383 Member Find all posts View Profile Close clarkie383]

How do you get around all they lights coming on?
Do you need to reset computer?

[cfryback Find all posts View Profile Close cfryback]

Okay, right... But I fail to see why it would shut down those systems considering they're completely unrelated? (unless that was sarcasm, which doesn't translate well over the internet &#128517.

That being said, after reading a few things I'm a bit worried that I've been sold a system without cats and with pre cats still in place, rather than a system with high flow cats and no pre-cats... Can anyone confirm the location of the cats for me?

Here is my system: https://www.dropbox.com/s/4aiixuaogu...01-48.png?dl=0

Hmmm.....I almost got this as well. This is where it comes from.

http://www.ebay.com.au/itm/152155536...%3AMEBIDX%3AIT

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Resetting won't help. They will simply come back on. Plus it disables the associated systems.

[Guest Close Guest]

The cats are located on the original headers.
The 02 sensor is in front of it. The post cat 02 sensor is located after it.
Remove either and you'll get xmas tree lights and various trouble codes.

The system you show looks like it either has small cats or small mufflers in the centre dual section.
You can see the 02 sensors fitted in the headers.
However the post cat 02 sensors seem to be way back before the small cat?/ mufflers.
This is way back, and will need wiring to be lengthened from original position.
As the post cat 02 seems to be before the cat?/muffler it won't work properly. And as there appears to be not cats because of its location. I suggest it's going to throw up TC's of 0430 etc. (cat system below efficiency).

How do I know all this? Been there before.

The VSC TRC etc all switches off because it's programmed that on a CE light it shuts down some systems incase they are the cause.

So my guess / opinion is this exhaust in its current style is going to cause you issues.

Trouble codes, some systems shutting off, and also will make your car not meet emissions. Which may mean it will not be passed by RTA during inspections.

Caveat emptor.

[Bonzo1 Lurker Find all posts View Profile Close Bonzo1]

Hmmm.....I almost got this as well. This is where it comes from.

http://www.ebay.com.au/itm/152155536...%3AMEBIDX%3AIT

Yep, that's the one. Still a good deal even with the issues I've run into with it I reckon.

The cats are located on the original headers.
The 02 sensor is in front of it. The post cat 02 sensor is located after it.
Remove either and you'll get xmas tree lights and various trouble codes.

The system you show looks like it either has small cats or small mufflers in the centre dual section.
You can see the 02 sensors fitted in the headers.
However the post cat 02 sensors seem to be way back before the small cat?/ mufflers.
This is way back, and will need wiring to be lengthened from original position.
As the post cat 02 seems to be before the cat?/muffler it won't work properly. And as there appears to be not cats because of its location. I suggest it's going to throw up TC's of 0430 etc. (cat system below efficiency).

How do I know all this? Been there before.

The VSC TRC etc all switches off because it's programmed that on a CE light it shuts down some systems incase they are the cause.

So my guess / opinion is this exhaust in its current style is going to cause you issues.

Trouble codes, some systems shutting off, and also will make your car not meet emissions. Which may mean it will not be passed by RTA during inspections.

Caveat emptor.

Okay this is becoming a bit clearer now. I unscrewed the O2 sensors before the CATs on the new exhaust and saw honeycomb so can confirm that they are in fact cats. That being said, I'm not sure what the previous owner was doing re: putting the sensors in before the CAT because as you're saying, it would normally cause a myriad of problems.

The only thing I can think of is that they may have been running a unichip or some kind of ECU tune in order to eliminate those codes. I'm going to ring up the place I bought it from tomorrow and see if they can shed any light on that.

As far as I know, the stock system has 2 CATs and 2 Precats/resonators/small mufflers... or that could be 4 CATS... basically 4 things that look like CAT's and I'm not 100% certain on what is what. 2 of them are just below the headers as you said, but the other two are located where the 2 on this new system are and also have the O2 sensors located before them.

So I have 2 options it seems:

1. Get the muffler shop to chop the CATs below the headers off my old exhaust and get them to re-weld them with a flange onto the new one and hope that they are the right ones for the right spot.

2. Buy 2 of these and screw them in to the post- CAT O2 sensors (which imo would be alright considering I do have CATs fitted). These type of devices work fairly well from what I can tell from a few websites. http://www.ebay.com.au/itm/90-DEGREE...EAAOSwU-pXsNN0

I'll see what info I can get from the place I bought the exhaust from and go from there. Either way, thank you for all the help so far Piggy, it was very useful!

[sunny120 Junior Member Find all posts View Profile Close sunny120]

There are only 2 cats on the exhaust system. No such thing as pre-cat. The sensor before the cat (closest to headers) is the air/fuel sensor. The sensor post cat is the O2 sensor. You can get rid of any number of mufflers/knock boxes after the cats and it won't affect the computer. Get rid of either sensor and you'll have warning lights popping up on the dash and really crap fuel economy as the ECU can't work out what air/fuel mixture to pump into the cylinders.
Going by the eBay link both sensors are before the cat. I'd be chopping original cats and welding new flanges as per pacemaker instructions for the extractors. Plug up the holes in the exhaust where the sensors are and running the sensors where they're meant to be. That way jobs done properly and you shouldn't get any lights up on dash.