This is what I was wondering. Normally the front o2 sensor code has not come up. If I clear the codes, drive around and recheck it: generally just those 2 rears show up. Disappointing because I paid a (albeit small) shop to replace and I was standing right there. New sensor and then re-wired/shrink wrapped everything. After all that, showed no activity. I found the blown fuse “after” I had that done. Idk if that woulda solved it because I actually did re-do 1 of the oxygen sensor wiring my self prior to that.VStar650CL wrote: ↑Sat Aug 27, 2022 4:51 amThe knock code won't even turn on the MIL and it's very unlikely it's causing your issue. The major causes of P0138/P0158 are exhaust leaks or malfunctioning sensor heaters. P0141 indicates the left bank rear heater is inop, and with a previous blown fuse, I'd say it's possible you have some wiring damage down there. BUT (big but), nothing about the rear O2's is used to run the engine. They're strictly there to monitor the cats and can't cause the sort of performance issues you describe. With rear codes in the system the ECM won't be monitoring, so you won't be getting P0420/P0430 to warn you if your cats have gone south. Clogging cats can cause those sorts of symptoms. The P0134 is also a different story, that's for the left bank front O2. The fronts are used to run the engine, so if that sensor is producing data that confuses the ECM, all sorts of performance problems could result.
VStar650CL wrote: ↑Sat Aug 27, 2022 8:58 amThe knocks throw codes but don't really affect performance. Lots of people with older rides drive around with KS codes and don't even know they're there, and on models older than '09 I've seen KS's pop up right after installing brand new ones. The front O2 is a different matter. Even if it's come-and-go, it's telling you something isn't good in the left bank. I'd suspect the front O2 itself or the wiring. Narrow band O2's with a cracked ceramic substrate can work intermittently and be very hard to diagnose, because they basically act like a wiring problem. So I think I'd try changing one or both (at least the left bank) before anything else.
I haven’t, but good point. I have the Bluetooth thing that connects to my phone, but it’s pretty detailed.fontana dan wrote: ↑Tue Aug 30, 2022 9:44 pmHave you looked at OBDII live data while the issue is occurring? It will help you solve it if you understand what is going on with the engine while it is bogging down.
You said someone has chopped up the wires on the O2s already? I would look there very closely for damage to the circuit.
Just seeing this. I still haven’t had a moment to read up the readings.fontana dan wrote: ↑Tue Aug 30, 2022 11:13 pmWhat voltage are they reading while theyre unresponsive at "flat line"?
Take a look at your long term fuel trims B1 & B2, as well as all upstream and downstream O2 sensor readings while the engine is running.
If the fuse was blown for your O2 heater that points towards a short to ground- bad wiring. If the heater is not functioning you could have an unresponsive O2 sensor.
Replacing the upstream sensors is not likely to fix the problem with the downstreams.
At wide open throttle, it’ll rev upwards to 5,600 (had to do this the other day to pass some idiot who cut me off)…but it’ll barely pick up much speed for a few seconds until it gets enough kick. It’s also “revving” on cruise control for the smallest of highway hills like I’m driving a Corolla. So I’ve been careful not to pull out into traffic unless there’s no cars nearby, because I won’t have enough speed to accelerate.fontana dan wrote: ↑Sun Sep 11, 2022 8:11 pmHow does the car run at wide open throttle(WOT)? What is the reasoning for fuel pump/filter?
One of the first steps i do in diagnosing a car with an issue like this, is to floor it and watch live data to make sure both upstream o2 sensors go rich (.9v). That will quickly show if fuel system is able to supply the engine with enough fuel.
You've already identified a problem area in the o2 WIRING. You need to test the circuit.
I asked the shop who put the o2 sensors in, he didn’t seem to think it would be necessary considering it still can drive long distance, and it’s not stalling out or anything. It’s just intermittently not getting power when pulling away from a stop, but then after a few seconds it’ll lunge into speed. However it’s now progressed to difficulty maintaining on highway here and there. It’ll cruise okay, but give it throttle, and it’s like trying to floor a semi lol.VStar650CL wrote: ↑Mon Sep 12, 2022 11:41 amThat sounds like an engine that can't breathe. With your rear O2's out of commission, might be worth throwing a vacuum gauge on it to see if you have a clogged cat. Should run 18~20 inches at idle, if it drops precipitously when you gradually roll the throttle on with no load, the exhaust is blocked.
I dunno, but I don't think it's a failsafe behavior. On late '90's stuff there were only a few DTC's that would trigger an ECM failsafe (in this case P0100, P0115 and P0120), and none of those are for the exhaust sensors. See EC-88 (pdf page 90):fontana dan wrote: ↑Thu Sep 15, 2022 10:04 amIf your front o2s are functioning then I would think the car should run ok. However I've heard of Nissans doing weird things when the rear o2s aren't working.
I'm just proposing the possibility that the dead exhaust sensor could be causing the ECM to do something weird with fueling. Good thinking though; if not an o2 issue I would bet the problem with this car lies with one of the sensors listed on EC-88.VStar650CL wrote: ↑Thu Sep 15, 2022 11:32 amI dunno, but I don't think it's a failsafe behavior. On late '90's stuff there were only a few DTC's that would trigger an ECM failsafe (in this case P0100, P0115 and P0120), and none of those are for the exhaust sensors. See EC-88 (pdf page 90):fontana dan wrote: ↑Thu Sep 15, 2022 10:04 amIf your front o2s are functioning then I would think the car should run ok. However I've heard of Nissans doing weird things when the rear o2s aren't working.
https://www.nicoclub.com/service-manual ... 8%2Fec.pdf
Lol no worries there, I can’t even afford that right now anyway.fontana dan wrote: ↑Thu Sep 15, 2022 10:04 amRemember to keep it simple...and do not even think about replacing those catalytic converters.