GOLFMK8
GOLFMK7
GOLFMK6
GOLFMKV

EQT E-Tuning Q&A

2013R

Drag Race Newbie
i have never heard of just disconnecting the rear O2 sensor in 12 years of owning GTI's. very interesting thought though.
 

uberpolka

Go Kart Newbie
Location
Portland
Car(s)
2017 GTI
Cool.


I would have thought unplugging would throw a check engine light. I'll give it a try and see what happens.



Would it be a problem to remove the rear o2 completely and plug the bung in the downpipe?
 

Ed @ EQT

GOLFMK7 Official Sponsor
Location
Fairfield, CA
Car(s)
MK8 Golf R
i have never heard of just disconnecting the rear O2 sensor in 12 years of owning GTI's. very interesting thought though.



Yea I think I’m the first the find that. I posted about it our FB group a while back.

*** off road use only! ***
 

2013R

Drag Race Newbie
I know absolutely nothing compared to you, but i was always under the impression that the rear O2 sensor was only to monitor catalytic efficiency, and had nothing to do with the engine fuel mixture. I thought only the front O2 sensor managed the engine tune.

link to the facebook post so i can study it?
 

uberpolka

Go Kart Newbie
Location
Portland
Car(s)
2017 GTI
Copy&Paste here for non FB account folk pls.


Sent from my iPhone using Tapatalk




NO facebook(but dat burner account...)


PSA:
I wanted to make folks aware of a small issue and general recommendation I make for all stage 2 and higher cars I tune via Cobb. With catless, high flow catted, and O2 spacer downpipes, the ECU will slowly add extra fuel at heavy load and will end up running fairly rich over time. This is a function of the rear O2 sensor being used to determine cat efficiency. Since the factory cats are not in place, it gets confused and continues to add fuel.



I have made Cobb aware of the issue and hopefully we will have a software solution eventually. But in the meantime, I recommend that people unplug the rear O2 sensor and leave it unplugged. The easiest place to do it is under the hood at the firewall. You will find two connectors here... disconnect the black one only. After doing this, I also recommend reflashing your latest map to reset any learning the ecu has done. Once this is done, your air/fuel ratios will remain consistent.
 

MSH

Drag Racing Champion
Location
Denver
Car(s)
'20 M2 Competition
Copy&Paste here for non FB account folk pls.


PSA:
I wanted to make folks aware of a small issue and general recommendation I make for all stage 2 and higher cars I tune via Cobb. With catless, high flow catted, and O2 spacer downpipes, the ECU will slowly add extra fuel at heavy load and will end up running fairly rich over time. This is a function of the rear O2 sensor being used to determine cat efficiency. Since the factory cats are not in place, it gets confused and continues to add fuel.
I have made Cobb aware of the issue and hopefully we will have a software solution eventually. But in the meantime, I recommend that people unplug the rear O2 sensor and leave it unplugged. The easiest place to do it is under the hood at the firewall. You will find two connectors here... disconnect the black one only. After doing this, I also recommend reflashing your latest map to reset any learning the ecu has done. Once this is done, your air/fuel ratios will remain consistent. *** off road use only! ***
 

Attachments

  • O2 Sensor.jpg
    O2 Sensor.jpg
    60.8 KB · Views: 577

Stija

Go Kart Newbie
Location
Az
Car(s)
BMW Saab Subaru VW
PSA:
I wanted to make folks aware of a small issue and general recommendation I make for all stage 2 and higher cars I tune via Cobb. With catless, high flow catted, and O2 spacer downpipes, the ECU will slowly add extra fuel at heavy load and will end up running fairly rich over time. This is a function of the rear O2 sensor being used to determine cat efficiency. Since the factory cats are not in place, it gets confused and continues to add fuel.
I have made Cobb aware of the issue and hopefully we will have a software solution eventually. But in the meantime, I recommend that people unplug the rear O2 sensor and leave it unplugged. The easiest place to do it is under the hood at the firewall. You will find two connectors here... disconnect the black one only. After doing this, I also recommend reflashing your latest map to reset any learning the ecu has done. Once this is done, your air/fuel ratios will remain consistent. *** off road use only! ***
Surprised you can’t just disable/turn it off like we do in Subaru world w Cobb AP mapping.
 

daconchslop

Autocross Champion
Location
SC
Car(s)
ACS SE/Tech
NO facebook(but dat burner account...)


PSA:
I wanted to make folks aware of a small issue and general recommendation I make for all stage 2 and higher cars I tune via Cobb. With catless, high flow catted, and O2 spacer downpipes, the ECU will slowly add extra fuel at heavy load and will end up running fairly rich over time. This is a function of the rear O2 sensor being used to determine cat efficiency. Since the factory cats are not in place, it gets confused and continues to add fuel.



I have made Cobb aware of the issue and hopefully we will have a software solution eventually. But in the meantime, I recommend that people unplug the rear O2 sensor and leave it unplugged. The easiest place to do it is under the hood at the firewall. You will find two connectors here... disconnect the black one only. After doing this, I also recommend reflashing your latest map to reset any learning the ecu has done. Once this is done, your air/fuel ratios will remain consistent.



SUP!


Sent from my iPhone using Tapatalk
 

Ed @ EQT

GOLFMK7 Official Sponsor
Location
Fairfield, CA
Car(s)
MK8 Golf R
Surprised you can’t just disable/turn it off like we do in Subaru world w Cobb AP mapping.



Yep I asked for that a long time ago. But the VW team has a lot on their plate.

— Ed
 

uberpolka

Go Kart Newbie
Location
Portland
Car(s)
2017 GTI

Diggs24

Autocross Champion
Location
de plains! de plains!
Car(s)
2015 GTI
Interesting. I have yet to catch it targeting anything other than what the tune has set for lambda at full load. Like, how long of a period until you start seeing things. Weeks, months? I think it's a Vibrant 200cell but I also have a bigdaddiesgarage minicat in front of the o2 sensor. I wonder if that's why it remains happy.....
 

Ed @ EQT

GOLFMK7 Official Sponsor
Location
Fairfield, CA
Car(s)
MK8 Golf R
Interesting. I have yet to catch it targeting anything other than what the tune has set for lambda at full load. Like, how long of a period until you start seeing things. Weeks, months? I think it's a Vibrant 200cell but I also have a bigdaddiesgarage minicat in front of the o2 sensor. I wonder if that's why it remains happy.....



That’s probably keeping it happy. If it sees “expected” cat activity this is not an issue.
 
Top