Oxygen and knock sensors
07-23-05 | 08:38 AM
#16
Lexus Connoisseur
Joined: Mar 2001
Posts: 19,802
Likes: 534
From: USA
Originally Posted by ArcherIII
It makes sense that if there was an issue with the knock sensors that the ECM would not let the tranny shift into overdrive, and it would retard the timing or increase the fuel mixture to a rich condition making your gas mileage drop. The knock sensors are of course listening for detonation and allowing the shift to overdrive would put increased load on the engine, making the detonation worse.
The manual recommends 91 octane but states that a lower octane can be used. I use 91 as recommended. The lower octane is probably fine under light load and cruise, but under hard acceleration it could cause knock which would the ECM to adjust. Again this leads to decreased performance and fuel mileage.
My first Toyota V6 was a 95 Camry. It occasionally had an issue with misfiring under hard acceleartion. Since the car was a short term lease I ignored it. Shortly before turning the car in I just so happened to be reading the manual to find out the fuel capacity. At that point I realized I should have been using premium all along. I immediately switched for what it was worth and the car then accelerated cleanly. Of course I cannot be certain that this was the problem but I suspect it was. Also many years ago a friend of mine had an issue with his Monte SS. I suggested he switch brands of gas since he had always purchased from the same place. Problem solved.
The manual recommends 91 octane but states that a lower octane can be used. I use 91 as recommended. The lower octane is probably fine under light load and cruise, but under hard acceleration it could cause knock which would the ECM to adjust. Again this leads to decreased performance and fuel mileage.
My first Toyota V6 was a 95 Camry. It occasionally had an issue with misfiring under hard acceleartion. Since the car was a short term lease I ignored it. Shortly before turning the car in I just so happened to be reading the manual to find out the fuel capacity. At that point I realized I should have been using premium all along. I immediately switched for what it was worth and the car then accelerated cleanly. Of course I cannot be certain that this was the problem but I suspect it was. Also many years ago a friend of mine had an issue with his Monte SS. I suggested he switch brands of gas since he had always purchased from the same place. Problem solved.
07-25-05 | 11:10 AM
#17
Driver School Candidate
Joined: Jul 2005
Posts: 46
Likes: 0
From: ca
Bad news , over the weekend i was out of town and so my parents drove the car around to test the car out. My dad said that the check engine light came back on and the reving came back on, when they was driving it home for work. Im bringing it to lexus again today at lunch to have them look at it agian. Do anyone know what the problem is and if it is related to the tranny?
i hope they can fix it or said it the tranny cuz it still under the powertrain warranty.
i hope they can fix it or said it the tranny cuz it still under the powertrain warranty.
07-27-05 | 11:21 AM
#19
Driver School Candidate
Joined: Jul 2005
Posts: 46
Likes: 0
From: ca
Originally Posted by Lil4cyl
Bored,
Not sure what the problem would be, but keep us posted on it please... could be they botched the knock sensor install somehow, and you are getting the same code again.
Not sure what the problem would be, but keep us posted on it please... could be they botched the knock sensor install somehow, and you are getting the same code again.
thank for everyone help.
07-27-05 | 12:48 PM
#21
Driver School Candidate
Joined: Jul 2005
Posts: 46
Likes: 0
From: ca
Originally Posted by Lil4X
Guess they "missed" the "test drive" part of the work order . . . 
Glad your problems are solved!
Glad your problems are solved!
So i guess the knock sensor does keep you car from going into a higher gear and it stay in safe mode sometime until you can get it fix. im soo happy that it such a easy fix and hopefuly will run smooth from now on.
thanks
10-24-11 | 03:43 PM
#22
Driver School Candidate
Joined: Oct 2011
Posts: 21
Likes: 0
From: Sterling, VA
Earlier this year I replaced an oxygen sensor in my car. TheCEL returned after awhile with a P0171 lean bank error code, and I continued to drive my 2000 RX300, which was probably a mistake. When I took it in this weekend it turns out it was a bad Denso sensor, that they replaced for free but now they are telling me that both my knocking sensors are bad. What I want to know is it possible that they aren't really bad and that just driving with a lean fuel mixture is giving a false reading and if i maybe clean the MAF and replace the spark plugs that the knocking sensors may be ok?
10-24-11 | 11:00 PM
#23
Super Moderator
Joined: Apr 2004
Posts: 17,250
Likes: 169
From: Miami, Florida
Earlier this year I replaced an oxygen sensor in my car. TheCEL returned after awhile with a P0171 lean bank error code, and I continued to drive my 2000 RX300, which was probably a mistake. When I took it in this weekend it turns out it was a bad Denso sensor, that they replaced for free but now they are telling me that both my knocking sensors are bad. What I want to know is it possible that they aren't really bad and that just driving with a lean fuel mixture is giving a false reading and if i maybe clean the MAF and replace the spark plugs that the knocking sensors may be ok?
10-24-11 | 11:47 PM
#24
Driver
Joined: Dec 2010
Posts: 154
Likes: 0
From: Indiana
The person who owned my RX before me had shifting issues. It turns out one of the knock sensors were bad. The knock sensor will cause shiftng problems.
As for the lean bank. Have you recently replaced your air filter? I know that there is a hose that connects to the airbox and can cause a vacuum leak causing a code to appear. Thats my two cents.
As for the lean bank. Have you recently replaced your air filter? I know that there is a hose that connects to the airbox and can cause a vacuum leak causing a code to appear. Thats my two cents.
Thread
Thread Starter
Forum
Replies
Last Post
VSsc400
RX - 1st Gen (1999-2003)
4
08-26-04 10:16 AM
