EQT Stage 2 - O2 sensor

[SmoothCat565]

I just got my AP w/ EQT stage 2 for my MK7 GTI. I installed a CTS downpipe w/ high flow cat which has a rear O2 sensor port before the cat. I also installed the ignition related upgrades. I haven't applied the tune yet or turned the car on at this point. It's still on the stock tune and on jack stands

The instructions from EQT are to disconnect the rear O2 sensor from the ECU for stage 2 tunes, so I took the O2 sensor out of line and not connected to the ECU, so it's not installed at all and I plugged the port with a threaded cap + washer that came with the DP.

Here are my questions:

1) When I install the tune, will it pass the O2 sensor portion of the inspection? I know it will clear the CEL but by following the instructions of disconnecting the O2 sensor, wouldn’t one fail inspection because it’s not connected? I live in an area which has the strictest emissions requirements. If the tune doesn’t have a way around that, then it becomes difficult for me because I have no sensor “proving” that I have a functioning cat. Even if I plug the O2 sensor in before inspection and just leave it dangling in the engine bay, there's no way that's going to make it pass the inspection right? Will a test instrument know it's not in line with the exhaust???

I really really don't want to flash back to stock and put on the stock downpipe because the stock downpipe is hard to deal with (barely go it out with help).

 

[Escape Hatch]

You will need to get an O2 spacer, have the O2 sensor plugged in and clear any codes. Drive the car for a bit to get readiness on emission modules and then get tested. The O2 sensor can be installed in the DP but just not plugged in when not trying to pass emissions. This will make it easiest when it is time to pass emissions once again. It is a yearly cycle I do not much care for.

 

[jimlloyd40]

I know that EQT recommends disconnecting it claiming it causes it to run slightly rich over time. I can tell you that I tested that for 5000 miles disconnected and 5000 miles connected and did not see any change in MPG or any evidence of running rich on the spark plugs. I drive 1000 miles per week so it was easy to test. I've left it connected ever since.

 

[shovelhd]

If the O2 sensor is not in the exhaust stream, it will throw a code.

In MA you are allowed one sensor not ready, but no faults. Check readiness with the tune flashed. If the downstream O2 sensor is the only one not ready, and you have no faults, then you're good. You need to have a way to check readiness.

 

[SmoothCat565]

I know that EQT recommends disconnecting it claiming it causes it to run slightly rich over time. I can tell you that I tested that for 5000 miles disconnected and 5000 miles connected and did not see any change in MPG or any evidence of running rich on the spark plugs. I drive 1000 miles per week so it was easy to test. I've left it connected ever since.

Nice! Do you pass inspection with EQT stage 2 with it plugged in?

 

[jimlloyd40]

Nice! Do you pass inspection with EQT stage 2 with it plugged in?

I don't because I have a catless Trackslag DP. Have to put OEM DP back in and flash to stock to pass. I don't know your state's rules.

 

[SmoothCat565]

If the O2 sensor is not in the exhaust stream, it will throw a code.

In MA you are allowed one sensor not ready, but no faults. Check readiness with the tune flashed. If the downstream O2 sensor is the only one not ready, and you have no faults, then you're good. You need to have a way to check readiness.

The O2 sensor is before the cat on my CTS downpipe. I live in MA. So are you saying I can pass inspection then with EQT Stage 2? The tune will get rid of CEL...so then I'm home free to pass inspection? Sorry if I'm misunderstanding, newbie learning as I go.

 

[jimlloyd40]

The O2 sensor is before the cat on my CTS downpipe. I live in MA. So are you saying I can pass inspection then with EQT Stage 2? The tune will get rid of CEL...so then I'm home free to pass inspection? Sorry if I'm misunderstanding, newbie learning as I go.

You have another 02 sensor further back. That's the one that the thread is about. You won't pass inspection with the first 02 sensor removed. And the tune just shuts off the CEL light but if you do a scan you would see that there is a stored code that inspection would see and fail you.

 

[SmoothCat565]

You have another 02 sensor further back. That's the one that the thread is about. You won't pass inspection with the first 02 sensor removed. And the tune just shuts off the CEL light but if you do a scan you would see that there is a stored code that inspection would see and fail you.

Sorry, these discussions can get a bit confusing. I am referring to the second O2 sensor in my initial post, which to my understanding is after the first cat on the stock DP, but before the single cat on my CTS DP. I do not plan to ever touch the first O2 sensor.

Good to know! Yeah, looks like I need to go stock for inspection. It seems like these situations are tough.

Maybe I'll try the stock tune and CTS DP with and without a spacer to see if I can get through inspection, and then flash to stage 2. Not really sure that's going to work, but I'm thinking to try that first.

 

[jimlloyd40]

Sorry, these discussions can get a bit confusing. I am referring to the second O2 sensor in my initial post, which to my understanding is after the first cat on the stock DP, but before the single cat on my CTS DP. I do not plan to ever touch the first O2 sensor.

Good to know! Yeah, looks like I need to go stock for inspection. It seems like these situations are tough.

Maybe I'll try the stock tune and CTS DP with and without a spacer to see if I can get through inspection, and then flash to stage 2. Not really sure that's going to work, but I'm thinking to try that first.

See @shovelhd post #4. He's from Massachusetts

 

[Escape Hatch]

Sorry, these discussions can get a bit confusing. I am referring to the second O2 sensor in my initial post, which to my understanding is after the first cat on the stock DP, but before the single cat on my CTS DP. I do not plan to ever touch the first O2 sensor.

Good to know! Yeah, looks like I need to go stock for inspection. It seems like these situations are tough.

Maybe I'll try the stock tune and CTS DP with and without a spacer to see if I can get through inspection, and then flash to stage 2. Not really sure that's going to work, but I'm thinking to try that first.

I run the catted CTS 3.5 inch downpipe and do as I explained in this thread and pass emissions. Simple, not overly complicated.

 

[SaucyMuffin]

I’m from MA with previous experience with EQT stage 2. Difference with me vs. you is I run a Unitronic DP with spacer for the O2 sensor. One day my wife surprisingly took the car for state inspection and I was like damn it, not knowing if it would pass readiness check. She had no issues, so you should be good. Oh and BTW I never touched the rear sensor, why would I have to if the tune is supposedly so good? I’ve switched for other reasons but you should be fine as long as the CTS DP itself doesn’t throw a code without a spacer.

 

[SmoothCat565]

I run the catted CTS 3.5 inch downpipe and do as I explained in this thread and pass emissions. Simple, not overly complicated.

Did you use a 42DD spacer or Vibrant J spacer, or another type? And are you flashing to stock and plugging in the sensor to pass? Or remaining tuned and plugging in sensor to pass?

 

[SmoothCat565]

I’m from MA with previous experience with EQT stage 2. Difference with me vs. you is I run a Unitronic DP with spacer for the O2 sensor. One day my wife surprisingly took the car for state inspection and I was like damn it, not knowing if it would pass readiness check. She had no issues, so you should be good. Oh and BTW I never touched the rear sensor, why would I have to if the tune is supposedly so good? I’ve switched for other reasons but you should be fine as long as the CTS DP itself doesn’t throw a code without a spacer.

Ya I like your DP way better because the O2 sensor port is actually after the cat lol. Good to know you passed with your tune/configuration man.

 

[Escape Hatch]

Did you use a 42DD spacer or Vibrant J spacer, or another type? And are you flashing to stock and plugging in the sensor to pass? Or remaining tuned and plugging in sensor to pass?

Vibrant J with the medium insert. It will sometimes give a cell on stock tune but it is mostly cell free, at least long enough for emissions. Plug the O2 sensor back in, clear codes and drive for about half hour. I rescan to validate if it is cell free at the testing site parking lot before giving them the car.