Slow response 02 issues
Thread Starter
Le Mans Master
Joined: Jul 2010
Posts: 5,407
Likes: 265
From: montreal quebec
Slow response 02 issues
Hey everyone, i need forum help like never! My tuner and i can't figure how to solve my issue. I did a little research, So basically, the issue comes from the fact that my front 02 sensors doesn't warm up enough because of not enough restriction in my 2'' primaries hearders and the fact that my X-pipe is catless as well! It causing partial throttle surge that is very annoying. Now i read few différentes things, first i could get my headers ceramics coated, also could swap front and rear 02, rear are staying hotter and i read that LG motorsports make a adapter harness.Some says modify 02 switching point, for whatever that means!! Obviously, Im not feeling like taking the whole exhaust system off for ceramics coating! Any suggestions/help will be appreciated, my tuner is also doing a lot of research on his side, i still have full trust in him!
Race Director
Joined: May 2004
Posts: 16,667
Likes: 1,209
From: Raleigh, NC
St. Jude Donor '15
Closed loop integrator/proportional and delay settings in tune can help with this. The switchpoints in gen 4 vehicles really doesn't seem to do much of anything--I've turned mine to extreme numbers and nothing really changed.
If the tuner doesn't have access to those parameters in your particular tune you or the tuner can request HPT add access to them (they haven't added them to every tune yet for whatever reason but they added them for me on mine).
There are some posts about it on the HPT forum. It's tough to get right but it can be improved quite a bit.
Being too cold is one issue, but the change in time it takes for exhaust to go from the motor to the O2 sensors is an issue as well since the O2 sensors are further away (the delay setting can help with this). The integrator/proportional settings change how much fuel is added/subtracted based on O2 readings. Right now yours is adding/taking away too much and probably doing it at the wrong time, which makes it chase it's tail and you get surging.
It will take time to get these as good as it's going to get, but IMO the tuner should spend some time on those settings before you bother with ceramic coatings, etc.
I've also read the "rear" O2 sensors work better in these cases but I have no experience with doing that, so I can't say whether it will really help or not. Can't hurt to try though.
If the tuner doesn't have access to those parameters in your particular tune you or the tuner can request HPT add access to them (they haven't added them to every tune yet for whatever reason but they added them for me on mine).
There are some posts about it on the HPT forum. It's tough to get right but it can be improved quite a bit.
Being too cold is one issue, but the change in time it takes for exhaust to go from the motor to the O2 sensors is an issue as well since the O2 sensors are further away (the delay setting can help with this). The integrator/proportional settings change how much fuel is added/subtracted based on O2 readings. Right now yours is adding/taking away too much and probably doing it at the wrong time, which makes it chase it's tail and you get surging.
It will take time to get these as good as it's going to get, but IMO the tuner should spend some time on those settings before you bother with ceramic coatings, etc.
I've also read the "rear" O2 sensors work better in these cases but I have no experience with doing that, so I can't say whether it will really help or not. Can't hurt to try though.
Last edited by schpenxel; Jun 24, 2016 at 08:59 AM.
