Ok I HAVE to finally get around to fixing this idle issue
03-08-13, 04:25 PM
#1
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Ok I HAVE to finally get around to fixing this idle issue
Some days the car idles extremely low, sometimes it idles through the roof around 3k. When it idles low the car will cut off so I have raised the rpm up by 800 to keep it from cutting off. This is fine and makes the car idle at normal 800-ish range, but when the issue stops and therm comes back up it is now in the 3k range because I've had to set the idle up really high so the car doesn't stall when it has its period and gets all bittchy on me.
I had an O2 code a while back, but after I rebuilt the computer I haven't been able to pull the codes since. Everything works great but no code retrieval and it didn't solve my issue.
It is not a vac line or vac issue, I know that. It is an electrical anomaly I do know that. I suspect it may be the O2 so I wanted to ask if anyone had heard of these symptoms with an O2 going on the outs and kind of half working? About 1 minute into turning the car on from dead cold the check engine light slowly fades on and stays on so I know it had just got to be a sensor.
I had an O2 code a while back, but after I rebuilt the computer I haven't been able to pull the codes since. Everything works great but no code retrieval and it didn't solve my issue.
It is not a vac line or vac issue, I know that. It is an electrical anomaly I do know that. I suspect it may be the O2 so I wanted to ask if anyone had heard of these symptoms with an O2 going on the outs and kind of half working? About 1 minute into turning the car on from dead cold the check engine light slowly fades on and stays on so I know it had just got to be a sensor.
Last edited by O. L. T.; 03-08-13 at 05:08 PM.
03-08-13, 04:32 PM
#3
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There is an idle set screw on the TB. It's just like any other in the same place on most carbs at the throttle cable pulley. This one is vertical on the very top controlling the stopper.
03-08-13, 05:02 PM
#6
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Oh I love my SC. Any other car you would have to jack up and climb under and go through HELL to get to the O2 to check it. The sc O2 goes straight through the floor and up the trans to under the radio. This is too easy to get to and check.
So now..... I don't have my FSM's here. Someone wanna spot me the O2 check procedures/readings from the FSM?
So now..... I don't have my FSM's here. Someone wanna spot me the O2 check procedures/readings from the FSM?
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03-08-13, 05:34 PM
#8
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I'm not missing it, it was not on the 92 model.
Has anyone tried the $33 O2 sensor on ebay that is listed for
OXYGEN SENSOR-DOWN
97-01 LEXUS ES300
98-99 LEXUS GS300
95-00 LEXUS LS400
96-97 LEXUS SC400
97-01 TOYOTA CAMRY
99-03 TOYOTA SOLARA
Has anyone tried the $33 O2 sensor on ebay that is listed for
OXYGEN SENSOR-DOWN
97-01 LEXUS ES300
98-99 LEXUS GS300
95-00 LEXUS LS400
96-97 LEXUS SC400
97-01 TOYOTA CAMRY
99-03 TOYOTA SOLARA
Last edited by O. L. T.; 03-09-13 at 05:05 PM.
03-09-13, 07:56 AM
#9
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I'm not missing it, it was not on the 92 model.
Has anyone tried the $33 O2 sensor on ebay that is listed for
OXYGEN SENSOR-DOWN
97-01 LEXUS ES300
98-99 LEXUS GS300
95-00 LEXUS LS400
96-97 LEXUS SC400
97-01 TOYOTA CAMRY
99-03 TOYOTA SOLARA
I unplugged the passenger O2 sensor and the hunt and peck idle went away completely. Guess that solves that............
Has anyone tried the $33 O2 sensor on ebay that is listed for
OXYGEN SENSOR-DOWN
97-01 LEXUS ES300
98-99 LEXUS GS300
95-00 LEXUS LS400
96-97 LEXUS SC400
97-01 TOYOTA CAMRY
99-03 TOYOTA SOLARA
I unplugged the passenger O2 sensor and the hunt and peck idle went away completely. Guess that solves that............
03-09-13, 02:46 PM
#10
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I dont think the O2 sensor will cause your idle issue. They are typically tied to the fuel trim part of the ECS only. If there is a problem with one it should just cause a rich condition by default and should not effect idle speed. If it does it will only be by 50-100 rpm.
It sounds like it is tps related. Im just now learning the 1UZ platform so i dont know all of the inputs and outputs the ECM is looking for. I had a similar problem on mine and adjusting the tps fixed it. In my searches for transmission related problems i found a thread of yours where you were adjusting the tps to gain firmer shifts i believe. As far a i can tell, the 1UZ does not have a separate closed throttle switch which would mean that the computer will rely on the tps to tell it when the throttle is closed. If the tps never shows closed throttle you are going to have a few systems trying to overcompensate in different situations. The computer wont know when the throttle is closed and wont run the correct idle map for the conditions.
I would suggest checking the tps setting to begin with, either the feeler gauge technique or i posted another quick way with the dlc voltages on another thread. The fsm procedure is in the transmission section of the fsm. I would also reset the idle screw that you said you have been adjusting to spec according to the fsm as well. Try to get the system back to factory settings and start from there because you can end up chasing your tail with a problem that could have been man made and no need to replace any parts.
It sounds like it is tps related. Im just now learning the 1UZ platform so i dont know all of the inputs and outputs the ECM is looking for. I had a similar problem on mine and adjusting the tps fixed it. In my searches for transmission related problems i found a thread of yours where you were adjusting the tps to gain firmer shifts i believe. As far a i can tell, the 1UZ does not have a separate closed throttle switch which would mean that the computer will rely on the tps to tell it when the throttle is closed. If the tps never shows closed throttle you are going to have a few systems trying to overcompensate in different situations. The computer wont know when the throttle is closed and wont run the correct idle map for the conditions.
I would suggest checking the tps setting to begin with, either the feeler gauge technique or i posted another quick way with the dlc voltages on another thread. The fsm procedure is in the transmission section of the fsm. I would also reset the idle screw that you said you have been adjusting to spec according to the fsm as well. Try to get the system back to factory settings and start from there because you can end up chasing your tail with a problem that could have been man made and no need to replace any parts.
03-09-13, 07:15 PM
#11
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I adjusted the tps Years ago and I can tell you it didn't have any effect other than my shift points at certain throttle position. This is something else entirely. This is a compensation of fuel/air and it can't decide what to do. It hunts and pecks the idle up and down. As soon as it compensates for whatever it compensated for it completely reverses its decision and goes the other way causing a roller coaster idle effect.
03-09-13, 08:17 PM
#13
The TPS should make a change. If it doesn't, then it could be the entire issue. My guess, it's the TPS. If you haven't yet, clean all of the TB crap, like the IACV, then move onto the ECU...I think this thread would help. https://www.clublexus.com/forums/sc-...ling-loop.html
Speaking of TPS, mine isn't set correctly...
Speaking of TPS, mine isn't set correctly...
03-09-13, 10:16 PM
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Actually thats exactly how i have seen many cars act with a bad or out of adjustment tps. I have seen iac valves and tps's cause that. A fuel trim usually wont cause that much fluctuation, you would have to be dumping tons of fuel then none at all and im sure your gas mileage would be absolutely horrible.