AFR Issues: Rise and then drop after drive time

[t.viggiano]

hello,

first post here but I am experiencing the following issue. new to tuning as well. truck also came with this tune and mods before I purchased.

when driving my truck around I have a AFR reading right around stoch or 1.0 lambda. however, after about 5 mins of driving, from a cold start or warmed up, my AFR goes lean by 10% for a little bit and then rich by nearly 10% and then seems to equalize out after a little further. on the log file this occurs at approx 3 min. any suggestions? truck info below as well as files..

2006 GMC Sierra
4.8L v8
BTR Cam/spring kit
Full Exhaust system
Innovate Wideband

please let me know if im missing information.

Thank you - Tyler

[LSandlteditor]

At Time frame 02:53:07.024 Your AFR commanded goes to 16.00 Thats is where your issues lie i believe. There is also a to be gained in the File itself. Your power enrichment tables need some massaging....as well as your VE table. The VE table has way to many jagged spikes and needs to be smoothed out. If you need more help, contact me and I can make something happen.

[anniversaryss]

Is cat over temp disbale?

[LSandlteditor]

It is disabled in his tune.

[LSandlteditor]

Is cat over temp disbale?

It is disabled in his tune file.

[anniversaryss]

Im sorry im not by my other laptop but this is a P59? If so im going to take a wild guess, do you have rear oxygen sensors hooked up? If you dont have them hooked up even with COT disabled it will still run the Cat test. This will cause wild swings in command AFR etc......

[t.viggiano]

yes the CAT stuff has been disabled because they are not currently installed from the previous owner. it is a p59 though. starting to wish i started with a stock truck but i am slowly learning. i will have to dive in more and see why its been commanded, but i would agree the tune needs work. its still a work in progress type thing. still learning to tune so thanks for the offer to help.

[anniversaryss]

yes the CAT stuff has been disabled because they are not currently installed from the previous owner. it is a p59 though. starting to wish i started with a stock truck but i am slowly learning. i will have to dive in more and see why its been commanded, but i would agree the tune needs work. its still a work in progress type thing. still learning to tune so thanks for the offer to help.

Install rear oxygen sensors. You dont even have to plug them into the exhaust, just need to be plugged into the harness. Try again.

[t.viggiano]

ok i think i found my answer much like anniversaryss suggested it appears to be a CAT because it matches this exact scenario mentioned by 5FDP in another thread found below..

"It's not a glitch, it's a cat test.

You will also notice that the commanded AFR goes to that 16.00, then drops to 13.XX right after and back to stoich.

This happens when you remove the rear o2 sensors from the vehicle. HP Tuner itself can not disable this test. Everytime I have run into this issue you have to plug the rear o2 sensors back into the harness so the circuits are not left open and just disable all the codes."

does not appear to have a software work around due to the P59 itself possibly.

https://forum.hptuners.com/showthrea...-for-no-reason

[anniversaryss]

ok i think i found my answer much like anniversaryss suggested it appears to be a CAT because it matches this exact scenario mentioned by 5FDP in another thread found below..

"It's not a glitch, it's a cat test.

You will also notice that the commanded AFR goes to that 16.00, then drops to 13.XX right after and back to stoich.

This happens when you remove the rear o2 sensors from the vehicle. HP Tuner itself can not disable this test. Everytime I have run into this issue you have to plug the rear o2 sensors back into the harness so the circuits are not left open and just disable all the codes."

does not appear to have a software work around due to the P59 itself possibly.

https://forum.hptuners.com/showthrea...-for-no-reason

Pretty sure this is where i found the answer many moons ago ��