Catless wonder?
 

Hey y'all.
I've got a question about cats. My car is an '03 S, so, typical 4 cats.

I did away with the mid-pipe cats some time ago, and, of course, no problem-o.

Now I've purchased a set of headers. Installing them will leave me catless. This poses a problem when it's time for annual emissions testing.

Here's my question: the headers have a bung for an o2 sensor near the collector. Because it's easier to swap mid- pipes than it is the header, is it possible that I could put the first o2 sensor in the header, and then the 2nd sensor after the cat in the mid-pipe?

Do any of y'all have any experience this way?

Oh, and, if ya wanna debate the morality of increased emissions from my catless car, please start a new thread to do so. This car is 80% track-only.... but it still has to drive there. Plus: if I lived 7 miles west of here, I'd be in a county with no emissions testing.... seems a bit arbitrary, yeah?

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I went full catless about a year ago. I never tried the setup you're talking about, so I can't help you there. But, I'm going to tell you that I got lots of trouble with o2 spacers trying to eliminate the CEL. I finally went with a factory ROW tune and that fixed everything for me.

The factory ROW tune somehow passes domestic emissions testing, even though it's not monitoring cats?
I have an aftermarket tune I run most of the year, which doesn't monitor cats, and so at i.m. testing, it comes back "not ready".

Waddya know?

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UK cars have both lambdas in what you call the cat mid pipe.

If you wanted to try a science project, I'd give it a try. Theoretically, it should work.

The ROW tune in my 1998 3.6 Boxster passed emission testing in WI.

Oooohhhhhh...... I didn't know that.
So..... i wonder if i sourced two UK mid-pipes, complete with cats, and just swap those in at testing - time..... ?

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And in WI is that a "sniff" test? Or is it a plug-in to the OBD test?
(And how many "not- ready" are you allowed there? Did it show "not ready"? Or did it show pass on the o2 sensors?

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I was a state inspector here in Texas and we had to do an emissions test in the city I'm in (no smog). With the factory ROW tune the ECU does not monitor the cats so it will show "N/A" during testing when plugged in, as only the monitors that are enabled by the tune will show "ready" or "not ready". Some cars have more monitors enabled than others for some reason (some cars don't have an SAI system here in the US for example). So, all of my enabled monitors with the factory ROW tune were "ready" during testing with no cats. However, it will obviously not pass a smog test.

It's a plug in OBD test. I'll look for the last report tomorrow and will post the info if found.

Im confused by this, but probably just because of terminology. To me, "smog- check" and "emissions- testing" are the same thing. Both terms refer to testing, without distinguishing method of testing.

Is that how you're using the terms?

If so, then the ROW tune won't pass a plug- into-obd2 test in your county in Texas?

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When I said emission testing (no smog) I meant to test emission using only the plug in obd2 method for results, and smog testing is to also test emission by inserting the sniffer probe into the exhaust system.

In my county we do not do sniff testing (will result into a fail with no cats), but we only test emission using the obd2 plug in method (only checks if enabled monitors are “ready”). Inspectors here are also supposed to do a visual test but many are not well educated and can’t tell the difference between a cat, resonator and muffler (especially in quick lube stores) so most of them skip the the visual test.

Ok. I was hopeful that's what you were saying.
I'm ready to give it a try, I think.

Next question:
Is this just a simple flash? I have a flash tool that came with the tune I bought from VRTuning. I can swap back and forth easily between the factory tune and the custom tune.
If I can find the ROW tune file, is it that easy? Or must it be programmed to my car / VIN or something?

Or is it deeper than that?


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You need a PST2 or PIWIS or equivalent which has the files with which you can upload.

Just an FYI from my smog guy

If they are using a CA standard OBDII test there were some changes put in place last Nov. (all shops due to update by 2020)

They can tell if the DME has been flashed by checking the CAL ID and/or drive cycle count.

They now count the amount of readiness tests and can check if they go automatically to "pass".

They also now monitor live data while the car is running and compare it to manufacturer supplied data to look for any variances.

If you live in a CA compliant state (I think there is 15 states now?) and you drive a 2001+ vehicle you get to swap everything back to stock every 2 years now :(

This is good (but crappy) information. Do you know which states are on that list? M guess is that Utah is NOT, as we tend to be at the back-of-the-line on these sorts of things.

so then once that's done, can I upload my custom tune back-n-forth as I've been doing already, with the VividRacing tool? Or will I have to have another custom tune created to work with the ROW tune? (it sounds like what I'm changing with Vivid's tune must be fewer parameters (shallower) than the ROW tune).

I had the Vivid tune made after I went to a larger TB, 987 airbox, etc etc. How will the ROW tune play with those mods?

I believe it’s that easy. Not sure how easy it is to get the ROW file. Mine was done on someone’s PIWIS that had the option.

Sucks to be in CA. Luckily, they are not that advanced in TX. Not sure about Utah

Catless wonder?
 

Dan, this is exactly how I run my car. I lengthened my sensor wires in my harness with twisted pair wire (didn’t mess with the actual sensor wires) and have never had a CEL for it. Passed emissions three times now.