2004 Lexus LS430 Misfire BAD
01-09-21, 07:05 PM
#61
Lexus Champion
I was thinking the same, since techstream doesn't see any voltage I dont think there is a problem on the wiring itself, what is strange to me is why the sensor measured between 0.30 and 0.40 volts when connected straight to the multimeter but 1.27 when its connected to the wiring harness, could a short inside the O2 sensor do that? Maybe a problem inside with the heating element (since it gets voltage) is shorting with the signal wire itself?
I know that sensor has to be bad because the B1S2 is measuring a rich condition, I'm amazed by how complicated modern cars are.
Thank you so much for your help, I'll order those sensors as soon as I can, one more question.
Until those sensors arrive, should I connect the O2 sensor again and run the car lean or keep it disconnected and run the car rich?
I know that sensor has to be bad because the B1S2 is measuring a rich condition, I'm amazed by how complicated modern cars are.
Thank you so much for your help, I'll order those sensors as soon as I can, one more question.
Until those sensors arrive, should I connect the O2 sensor again and run the car lean or keep it disconnected and run the car rich?
01-09-21, 11:26 PM
#62
Pole Position
Spot on. And your cats will likely smell like rotten eggs so don't be planning to leave it like that for too long as broken cats get expensive real fast.
01-10-21, 01:37 PM
#64
Lexus Champion
That's also why I'm not going to blame the O2s for the misfire, I'm convinced it's from a leak somewhere else or a VVT issue assuming the ignition was already checked and I believe it was. Same thing with fuel injectors since you don't normally see 4-6 drop out at once, if it's a full bank then it's something common to that side
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infojunky (01-10-21)
01-10-21, 02:40 PM
#65
Instructor
It's much safer to run an engine rich than lean, to a point. If it's so rich it destroys the cats then lean is better. If it were me I would leave the sensor disconnected because the closed-loop fuel map is pretty close and shouldn't damage anything. Obviously no hot-rodding until the issue is fixed.
01-10-21, 03:21 PM
#66
Pole Position
That's also why I'm not going to blame the O2s for the misfire, I'm convinced it's from a leak somewhere else or a VVT issue assuming the ignition was already checked and I believe it was. Same thing with fuel injectors since you don't normally see 4-6 drop out at once, if it's a full bank then it's something common to that side
And what stood out was a very broken o2s1 (on the side with the missfires) along with very negative long term fuel trims and lean reading secondary o2's (what?! They should be reading richer if it really were really running that rich)
When my vvt solenoid went bad, the car had missfires and my long term fuel trims were all over the shop ie. +18, -12, +5, -20.... in rapid succession. And 'missfires' didn't go away magically after a computer reset. Where as here the car is running smooth with no missfires after reset, yet o2's are obviously still broken / appear out of spec. The the missfires start after compensations are applied.
When o2's are broken, they affect everything, and can manifest as lean missfires. The worst is when they appear to work but are in fact out of spec but not enough to be obviously broken.
Either way the O2's need fixing regardless of a potential other secondary problem.
05-25-21, 07:06 AM
#67
Rookie
Thread Starter
Hello everyone, sorry for getting back to you like 5 months late, so today my o2 sensor arrived, B1S1, I disconnected the old one, connected the new one and still, techstream was reading 1.27v at B1S1 turned off, I'm not sure what to do now, maybe take it to a mechanic that works on electrical stuff specificly, I think this is getting too complex for me.
05-31-21, 07:54 AM
#68
Hello everyone, sorry for getting back to you like 5 months late, so today my o2 sensor arrived, B1S1, I disconnected the old one, connected the new one and still, techstream was reading 1.27v at B1S1 turned off, I'm not sure what to do now, maybe take it to a mechanic that works on electrical stuff specificly, I think this is getting too complex for me.
07-13-22, 10:58 PM
#69
B1S1-0.00v
Hello everyone, sorry for getting back to you like 5 months late, so today my o2 sensor arrived, B1S1, I disconnected the old one, connected the new one and still, techstream was reading 1.27v at B1S1 turned off, I'm not sure what to do now, maybe take it to a mechanic that works on electrical stuff specificly, I think this is getting too complex for me.
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