RX300 knock sensor replacement DIY
09-06-19, 10:09 AM
#166
Driver School Candidate
As I recall there was just one ground wire on the back of the plenum but definitely two on the Passenger side.
Also, a tip I like is to thread bolts or screws back on parts a couple of turns (if easy) so they don't get mixed up or lost. In other cases, If there is just one loose bolt. I.e. a ground bolt. I stick a piece of masking tape on it and make a quick note. Having various single bolts or nuts on the workbench makes me uncomfortable.
Also, a tip I like is to thread bolts or screws back on parts a couple of turns (if easy) so they don't get mixed up or lost. In other cases, If there is just one loose bolt. I.e. a ground bolt. I stick a piece of masking tape on it and make a quick note. Having various single bolts or nuts on the workbench makes me uncomfortable.
09-30-19, 12:50 PM
#167
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What should I request be checked, with respect to the timing belt? (on the chance that it is causing the code)
Also, does the knock sensor problem ever result in intermittent unresponsiveness at acceleration (from a stop)?
It seems as though the car isn't "getting the message' when we press the accelerator...then suddenly it kicks in and
surges forward. A bit unsettling and we wonder if the two are possibly related... New transmission only 40K ago, so
we don't think transmission is involved.
09-30-19, 12:58 PM
#168
Driver School Candidate
I had intermittent problems with acceleration prior to the fix. From a stop the car wouldn't change into low gear. It was quicker to restart that car to get acceleration. It was quite hazardous. I believe the shifting issues are because the the car is running "limp mode" or open loop mode since the knock sensors are not responding. My car hasn't had that problem since I replaced the sensors about 2 months ago.
10-19-19, 12:34 PM
#169
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I realize this is an ancient post. But the time to address the knock sensor issue on our 01 RX300 has long past. Been disconnecting the battery, fooling the computer for 2 months. meantime, the vehicle is no longer dependable. Being an old used car service manager and a past hot rod builder, I'm know my way around engines. But This job is kicking my butt! Apparently, some "MOTHER" removed the hidden nut. Perhaps when the T belt was changed before our purchase. The bloody hidden bolt behind the TB seems to have been 'rounded' off. No matter what I try, and what tools I've used it just ain't coming off. The only solution I see, get an extended sawzall blade and cut the steel pipe leading to the hidden nut. Do I really need it anyway. I hate to junk the car, but it seems eminant with 190K. Damn, $690. worth of tires 4 months ago 
10-19-19, 11:01 PM
#170
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Thread Starter
Use the right tool. On rounded off nut/bolt, you need the squeezing kind of wrench/socket. You need some kind of wratchetting action and not much torque should be needed. Clearly the novice [who messed up the things for you] did not use the exact size socket/wrench and or forgot to flip righty-rtighty rule ... working from the other side.
Salim
Salim
10-25-19, 07:18 PM
#171
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stripped nut
Use the right tool. On rounded off nut/bolt, you need the squeezing kind of wrench/socket. You need some kind of wratchetting action and not much torque should be needed. Clearly the novice [who messed up the things for you] did not use the exact size socket/wrench and or forgot to flip righty-rtighty rule ... working from the other side.
Salim
Salim
As posted: The only solution to freeing the hidden bolt is the sawzall the bloody reinforcement bar. I see other issues ahead. But that's my start before losing a heap of money and sending this thing to the bone yard!
10-25-19, 10:15 PM
#172
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Thread Starter
It is tight space. Good luck with power tool.
Salim
Salim
07-07-21, 11:47 AM
#173
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I replaced both Knock Sensors & Harness, thank u all for the excellent write up, especially SalimShah.
Installing the bolt behind the C bracket that supports AIC was the hardest, the work around was, I took the bracket off, tightened the bolt to the AIC (forgot to torque it, I believe it was 14 in- Lb). With this you can gingerly put the AIC back, its tight though, however I found it difficult to put the ground to the AIC with this workaround. I bolted the ground to the Bank 1 head cover, where it holds down one of the hold-down of the engine harness. I made sure the contact was good.
I replaced the following while I did this:
Bypass Hose
Valve cover gaskets
Spark Plugs
Spark Plug Tube Gasket
PCV
All Gaskets (manifold, AIC, Throttle body)
Thermostat
Cleaned Throttle body & IACV
Upper & Lower Radiator Hose
Flushed Power Steering Fluid ( used vacuum method)
Flushed coolant
Replaced Radiator
Muffler
Exhaust pipe in front of the muffler which includes the resonator and the last cat from the engine
All went fine, took it out for a long drive, I noticed sluggish shifting from gear one to two, it was code P1150.
Went ahead and replaced B1 S1 sensor with OEM, which is Denso.
I'm approx. at $1950, I still have sluggish shifting from gear one to two. Checked online if something needs to be reset after knock sensor replacement, in one site “fixit” something, someone had similar experience after replacing knock sensor. The online tech's advice was to reset ECM.
Anyone had this sluggish shifting from gear one to two after replacing knock sensor?
Installing the bolt behind the C bracket that supports AIC was the hardest, the work around was, I took the bracket off, tightened the bolt to the AIC (forgot to torque it, I believe it was 14 in- Lb). With this you can gingerly put the AIC back, its tight though, however I found it difficult to put the ground to the AIC with this workaround. I bolted the ground to the Bank 1 head cover, where it holds down one of the hold-down of the engine harness. I made sure the contact was good.
I replaced the following while I did this:
Bypass Hose
Valve cover gaskets
Spark Plugs
Spark Plug Tube Gasket
PCV
All Gaskets (manifold, AIC, Throttle body)
Thermostat
Cleaned Throttle body & IACV
Upper & Lower Radiator Hose
Flushed Power Steering Fluid ( used vacuum method)
Flushed coolant
Replaced Radiator
Muffler
Exhaust pipe in front of the muffler which includes the resonator and the last cat from the engine
All went fine, took it out for a long drive, I noticed sluggish shifting from gear one to two, it was code P1150.
Went ahead and replaced B1 S1 sensor with OEM, which is Denso.
I'm approx. at $1950, I still have sluggish shifting from gear one to two. Checked online if something needs to be reset after knock sensor replacement, in one site “fixit” something, someone had similar experience after replacing knock sensor. The online tech's advice was to reset ECM.
Anyone had this sluggish shifting from gear one to two after replacing knock sensor?
Last edited by mtom01; 07-07-21 at 11:48 AM. Reason: spelling
08-04-21, 04:07 PM
#174
Driver School Candidate
The red perfect circle is hex (allen-key bolt head). Dont remember the size.
The little red circle are inverse torx #E6. These studs hold the V-Bank cover. You dont need to remove them unless you have to deal with the harness.
If you read my post, I state that the boxes jest fell apart for me and the coat hanger + high temp loam is how I lifted the wires above the hot head. I had to cut holes to get the wires out at the right distance. [Hyper: on mine they looked ok till I touched them and they crumbled]
PLEASE make sure you use the high temp loam and not the ordinary black loam that is sold for stereo wires. You may have to order it ... most stores, including auto stores do not carry this. A friend of mine who is building a kit car gave me a 3ft piece.
I checked with Lexus of Austin and they said you have to purchase the whole harness $$$$.
Salim
The little red circle are inverse torx #E6. These studs hold the V-Bank cover. You dont need to remove them unless you have to deal with the harness.
If you read my post, I state that the boxes jest fell apart for me and the coat hanger + high temp loam is how I lifted the wires above the hot head. I had to cut holes to get the wires out at the right distance. [Hyper: on mine they looked ok till I touched them and they crumbled]
PLEASE make sure you use the high temp loam and not the ordinary black loam that is sold for stereo wires. You may have to order it ... most stores, including auto stores do not carry this. A friend of mine who is building a kit car gave me a 3ft piece.
I checked with Lexus of Austin and they said you have to purchase the whole harness $$$$.
Salim
Would this gray wire loom work? It states its good up to 275 degrees.
08-04-21, 06:10 PM
#175
Moderator
Thread Starter
See if you can get one for 300C. I am not sure what was the ring for the one I used as it was given to me.
Salim
Salim
08-04-21, 06:13 PM
#176
08-04-21, 07:53 PM
#177
Moderator
Thread Starter
08-04-21, 08:59 PM
#178
But - maybe I missed where the tubing is being used - but for me if the application is on the outside of the engine (ie not in the area between banks where the knock sensors are) and not touching any part of the block I would say that tubing would be ok.
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