minimarine09

iTrader: (18)

Ok so, Ijust recently switched to sd, been cruising around in closed loop perfect, car feels great. Then lately I've noticed during cruise my afr is pegged rich, I let go of the throttle, pegged lean so I don't suspect a leaky injector really.

I've changed my front o2 twice with brand new ones. During cruise the o2 sensor voltage stays stuck around .3 sometimes seeping to .1 whenever I'm reading full rich.

But then strangely in the same cruise the o2 sensor will start sweeping normal .1-.9 and afr is perfect around 14.7.

I'm stumped, I think it's a grounding issue with the o2 sensor wiring. Maybe triggered by bumps in the road. What do you guys think?

minimarine09

iTrader: (18)

Any input would be much appreciated

minimarine09

iTrader: (18)

Bump, any input guys?

CDrinkH2O

iTrader: (7)

You really need to gather some more information if you want us to remote diagnose this one for you. There are a lot of variables involved so you need to narrow them down one at a time.
If you did the SD conversion, did you mess with the front O2 sensor?
What ROM are you on?
Can you post up a log of Load, TPS, WBO2, ST O2 trim, LT Mid and Low fuel trims, front O2 voltage as you cruise?
At what load values and TPS% do you switch from Closed Loop to Open?

minimarine09

iTrader: (18)

hey my bad,

i only replaced my front o2 sensor twice when i was on maf, i havent touched my o2 sensor since then,

my rom is 94171715

ive been logging alot so i can catch it in the act. i cant post one up at the moment but i cruise at ~24% tps average load is high 30s to mid 40s cruising. inbetween 2000- 2500 rpm so im definitely in closed loop by the settings that i show below, just sometimes the afr would be full rich, like the o2 sensor isnt sending a sweeping signal and the voltage would show that its stuck, but then out of nowhere it just starts working again.

open loop wont be triggered tps wise until 60%, and load in cruising rpms isnt until 88.1.

i un bolted all the grounding points that i found in the engine bay, filed the paint off of the body, cleaned up the terminals a bit, then tightened them back down and the issue has NOT popped up again yet, hopefully this fixed my issue, does anyone know which grounding point the o2 sensor ground is located? just to be sure. ill update in a bit to say whether or not this fixed my issue, its looking promising though!

if anyone has had this issue before please feel free to leave your input, or maybe some guys out there are having stuck or lazy o2 sensor issues and hopefully my solution helps! because i kept getting this issue even though i replaced the o2 sensor multiple times.

either way hopefully this fixed my problem

CDrinkH2O

iTrader: (7)

I'm glad you've been able to make some progress. Let us know if you need help to analyze your logs if this crops up again.

The front O2 sensor receives a 12V input from the MFI relay (in the long thin black plastic relay box in the engine bay, 5th relay from the front of the vehicle) on the red-yellow sensor wire. Output from the front O2sensor, on the red-blue wire, connects directly to pin 60 on the ECU. The sensor voltage drives an ADC circuit and is finally earthed internally in the ECU. This should allow you to run continuity checks to isolate any bad wiring or connections. If the internal earth for the ECU was bad then nothing would work properly so I doubt it is that.

Good luck with the troubleshooting.

minimarine09

iTrader: (18)

Awesome thank you!!! Will do