Values to change for gutted stock cat

[scirocco44]

2007 CX-7 2.3T
Gutted the catalyst out of the first cat but still have the second cat. Car is throwing a code for oxygen sensor. I'm not sure which values to adjust first to account for the the delete. Any help would be greatly appreciated.

Edit: Aside for a K&N filter, the car is completely stock.

 

[L337TurboZ]

You dont adjust values you turn off DTCs for the rear O2 (Bank 1 Sensor 2) and Catalytic converter (P0420 etc). What software are you using?

 

[scirocco44]

Thanks for the reply. I’m using Versatuner. I’ve already cleared the code and entered the codes to keep from flashing but the dtc always returns.

 

[Tomas]

If the DTC is unchecked are you still getting the same DTC?

 

[scirocco44]

If the DTC is unchecked are you still getting the same DTC?

It’s the exact same code. I’ll let VT know to kill the code and it comes back anyway.

 

[SharksInSpace]

If you disabled the DTC when flashing the tune then how is it throwing the DTC? What specific code(s) did you disable (when flashing, not just telling it to clear DTCs through the diagnostic feature after the car is running), and what specific code is it throwing?

 

[L337TurboZ]

What we are saying is you can clear codes or you can disable codes. There should be settings for which DTCs the ECU can report. Removing codes for the rear O2 and converter should prevent the CEL from turning on

 

[scirocco44]

What we are saying is you can clear codes or you can disable codes. There should be settings for which DTCs the ECU can report. Removing codes for the rear O2 and converter should prevent the CEL from turning on

I looked a little closer and it was a P2248. I checked off all of the ones except that one. So the car is idling very rough still. So getting rid of the codes does nothing except keep the light off right? Is the ECU still adjusting the fueling for the oxygen sensor data? Thats what i was led to believe.

 

[SharksInSpace]

Ok, I'm sorry, but I really feel the need to clarify the vague wording and make sure you understand the differences in verbiage, and that you are properly setting up VT when flashing your tunes. After you hit Flash on your selected tune file, and hit Next at the first pop-up screen, the second screen is Tune Customizer. On this screen, hit Edit Settings and click on the Disabling DTCs tab.

This is where you disable the codes relevant to the work you did, i.e. the ECU will no longer throw a CEL or flag that these particular aspects are an issue. If you haven't set that up, do so and reflash the map to eliminate any frivolous codes you're currently seeing that don't need to be paid attention to. Once that's done, we can begin further diagnosis knowing that we are all actually on the same page and are seeing only relevant codes.

Moving on, P2248 is not a code that VT is able to disable (at least not on my second gen), meaning it is probably not one that you want to arbitrarily disable. Google tells me that this code designates "O2 Sensor Reference Voltage Performance Bank 2 Sensor 1." Since you recently messed with the downpipe to gut the cat, you need to revisit exactly what you did during removal/install, and make sure that you fully threaded and tightened both of the sensors and fully seated each of their harness clips. If that all appears to be in order, you are probably looking at needing to replace the offending sensor. Unfortunately, I do not know if Mazda designates primary/secondary o2 via the "Bank" designation or the subsequent "Sensor" designation, but my guess based on your rough idle is that Bank 2 Sensor 1 may be referring to your primary o2, as that's the one that really affects fueling on these cars. Check the connections, especially those pain in the ass harness clips, and maybe pull the sensor out of the downpipe to inspect the probe for signs of excessive fouling or unusual wear.

 

[scirocco44]

Ok, I'm sorry, but I really feel the need to clarify the vague wording and make sure you understand the differences in verbiage, and that you are properly setting up VT when flashing your tunes. After you hit Flash on your selected tune file, and hit Next at the first pop-up screen, the second screen is Tune Customizer. On this screen, hit Edit Settings and click on the Disabling DTCs tab.
View attachment 16042
This is where you disable the codes relevant to the work you did, i.e. the ECU will no longer throw a CEL or flag that these particular aspects are an issue. If you haven't set that up, do so and reflash the map to eliminate any frivolous codes you're currently seeing that don't need to be paid attention to. Once that's done, we can begin further diagnosis knowing that we are all actually on the same page and are seeing only relevant codes.

Moving on, P2248 is not a code that VT is able to disable (at least not on my second gen), meaning it is probably not one that you want to arbitrarily disable. Google tells me that this code designates "O2 Sensor Reference Voltage Performance Bank 2 Sensor 1." Since you recently messed with the downpipe to gut the cat, you need to revisit exactly what you did during removal/install, and make sure that you fully threaded and tightened both of the sensors and fully seated each of their harness clips. If that all appears to be in order, you are probably looking at needing to replace the offending sensor. Unfortunately, I do not know if Mazda designates primary/secondary o2 via the "Bank" designation or the subsequent "Sensor" designation, but my guess based on your rough idle is that Bank 2 Sensor 1 may be referring to your primary o2, as that's the one that really affects fueling on these cars. Check the connections, especially those pain in the ass harness clips, and maybe pull the sensor out of the downpipe to inspect the probe for signs of excessive fouling or unusual wear.

So I did some checking. Had an exhaust leak in the downpipe gasket that meets with the second cat. Re gasketed the pipe, cleared the code and it stayed away for days and ran considerably better. The code just came back on today and now I'm at a loss. The code that popped up was a P2245 code. Also saw an "O2 Sensor Voltage High" and an"O2 Sensor No Voltage detected" Seems completely random in the codes its throwing.

So if I'm understanding what you're saying, the first O2 sensor is the sensor that controls fueling and that sensor would be the source of my rough idle. So what is the purpose of the second sensor.? It seems that's what the codes are referring to as the offending sensor.
I'll pull it after the car cools off a bit to check for fouling but what does the ecu use the downstream sensor for?

 

[L337TurboZ]

The purpose of the second oxygen (Bank 1 Sensor 2) sensor is to determine the quality of the exhaust gasses after they have passed through the catalytic converter.

The primary oxygen sensor (Bank 1 Sensor 1) is for monitoring the combustion quality. This oxygen sensor is what determines the Air to Fuel ratio. If the engine runs rich, and the ECU sees the increase it fuel, it then reacts and removes fuel. Your Short Term Fuel Trim is basically what the O2 sensor is reading but in a different format. Your Long Term Fuel Trim is the average the ECU has read over a period of time.

The ECU will throw a P0420 code (Catalyst Efficiency Below Threshold) when it sees that the rear O2 has seen a decrease in quality of exhaust gasses after they have passed the converter.

 

[scirocco44]

The purpose of the second oxygen (Bank 1 Sensor 2) sensor is to determine the quality of the exhaust gasses after they have passed through the catalytic converter.

The primary oxygen sensor (Bank 1 Sensor 1) is for monitoring the combustion quality. This oxygen sensor is what determines the Air to Fuel ratio. If the engine runs rich, and the ECU sees the increase it fuel, it then reacts and removes fuel. Your Short Term Fuel Trim is basically what the O2 sensor is reading but in a different format. Your Long Term Fuel Trim is the average the ECU has read over a period of time.

The ECU will throw a P0420 code (Catalyst Efficiency Below Threshold) when it sees that the rear O2 has seen a decrease in quality of exhaust gasses after they have passed the converter.

So since the first cat is removed and the exhaust gases have not been treated, the rear o2 sensor should be throwing a fault code. But instead it's throwing a no -high or low voltage code (randomly) for that sensor. This is more indicative of a faulty sensor?
And just so I understand, a faulty rear o2 sensor cant cause the car to idle rough?

 

[steve@versatune]

So since the first cat is removed and the exhaust gases have not been treated, the rear o2 sensor should be throwing a fault code. But instead it's throwing a no -high or low voltage code (randomly) for that sensor. This is more indicative of a faulty sensor?
And just so I understand, a faulty rear o2 sensor cant cause the car to idle rough?

The rear O2 sensor has minimal input on fuel trims. It is there to determine whether the primary cat is doing its job.
When running catless, expect to get and mask the catalyst efficiency DTC. Also plan to adjust BCSDC base a bit as the turbo will spool sooner and spike a bit more on initial spool up.

 

[scirocco44]

The rear O2 sensor has minimal input on fuel trims. It is there to determine whether the primary cat is doing its job.
When running catless, expect to get and mask the catalyst efficiency DTC. Also plan to adjust BCSDC base a bit as the turbo will spool sooner and spike a bit more on initial spool up.

Thank you so much for the help. Yeah the turbo overboosted and the computer initiated a fuel cut at WOT after the cat was removed. I did not know what values to change to counteract this but now I have an idea.

 

[scirocco44]

The rear O2 sensor has minimal input on fuel trims. It is there to determine whether the primary cat is doing its job.
When running catless, expect to get and mask the catalyst efficiency DTC. Also plan to adjust BCSDC base a bit as the turbo will spool sooner and spike a bit more on initial spool up.

Hey Steve would I adjust the BCSDC based on the IAT or the BASE DC? If it's only spiking slightly im assuming the adjustments required would only be slight adjustments?

 

[steve@versatune]

Modify the bcs dc base table downward slightly with a focus around 2500-3000 rpm where the boost will tend to spike on initial spool up.