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RX300 knock sensor replacement DIY

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Old 03-11-13, 09:36 AM   #46
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thank you for great diy information, i spend 10 hrs to replace it, (remind) also we need to un-screw 4 bolts on the left side coolant intake hose and engine mount (3 bolts) for replace the gasket!
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Old 03-11-13, 11:25 AM   #47
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thank you for great diy information, i spend 10 hrs to replace it, (remind) also we need to un-screw 4 bolts on the left side coolant intake hose and engine mount (3 bolts) for replace the gasket!
Fell free to quote and edit the post in the DIY thread. We should keep evolving/improving the DIYs.

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Old 03-27-13, 08:56 AM   #48
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To SALIMSHAH:

Your DIY on the 99 rx is right on! My rx was to the point that it would not shift into overdrive at all and would stall when cold shifting into gear. It now runs like a top...replaced the rear bank coil packs, knock sensors, gaskets, plugs and one vacuum switch...and wine for my assistant...less than $900!!!!!!

Thanks so much.

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Old 04-05-13, 05:24 PM   #49
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Difficulty level 6/10. Time 6-8 hrs

Tools needed:
Phillips screw driver, allen key, torx screw driver.
8,10,12,14mm sockets & wrenches
Assorted 1/4" 3/8" extensions and or adapters.
27mm wrench [I used adjustable wrench]
Torque wrench
torx socket
Trough to catch coolant.
3m Blue masking tape.
Marker/tags to mark where the hoses go. [if you rely on memory alone, you may be in trouble]

Material:
Knock sensors [take your vin number to parts as a switch was made]
Wire harness [most probably the old can not be reused]
3/4" high temp (gray) wire loom * [if your wire harness carrier box crumbles or is crumbling .. replacement with harness is over $1000]
coat hanger or stiff wire *
Lexus/Toyota coolant [I used conc red 1 jug]
2 Gallons distilled water. [you will need 1.25 gal approx]
Air plenum gasket set.
Shop Vac.

Other things to consider:
Since the top of the engine block is going to be removed, you may seriously think about changing the spark plugs and cleaning IACV.

General procedure: Slide a narrow socket over the pin end of the plastic hold down pins .. this squeeze the clips and you can lift the pin out. Loosen all bolts one or two turns instead of removing one bolt completely. Leave one or two bolts partially threaded and shake the component free. Similarly thread all nuts and bolts but do not tighten them down before seating (gently shake) the piece in. Then face evenly and then torque them evenly in criss-cross pattern. Always undo the most difficult fastener first and during assembly tighten it first. [for head gaskets work your way from middle to out during assembly].
Clamps on hoses should be moved over and clear across the barb. Twist each hose to break the seal before attempting to pull. During assembly gently twist the hose on. Make sure there is no twist/kink in the hose in its final state. Position the clamps in their original position (which typically is positioned to provide easy access).
All electrical connectors have a clasp to hold wires and provide slack and support. Make sure when you finish the job, you make no compromises. Inspect each hose/pipe/connector and replace them if you think they may need replacement.


1. Make sure the engine is cold.
2. Disconnect the battery.
3. Drain the coolant from bottom of the radiator and engine block [near oil filter for FWD]. Will take about 1/2 hr to drain out. [You can do a partial drain as well. Much simpler to drain all other wise you have to estimate how much to drain ... coolant level must drop below the intake level, else you will have coolant in the intake manifold.
4. Tape two strips of 3M and put it on the wind screen along the edge of wiper.
5. Remove the wiper arms by undoing the nuts that hold the wiper.
6. Remove the plastic hold down rivets and remove the two ventilator pieces. [plastic below the wiper arms]
7. Disconnect the wires for the wiper motor and remove bolts and lift off the wiper motor-arm assembly.
8. Remove bolts and lift out the outer cowl top panel [metal box].
9. Remove air filter and filter box [note two hoses that come to the box + hose and carefully unhook the acc cable].
10. Remove the acc cable. Loosen the lock nut and pull out the slug from the butterfly wheel.
11. Do the same with the cruise control throttle cable.
12. Remove the v-bank cover ("L" and 3 hex-key nuts)
13. Disconnect the maf connector. Loosen the phillips screw wire clamps of the air intake. Remove the air intake.
14. Mark and disconnect hoses attached to the throttle body [TB]. Disconnect the two electrical connectors. There are 3 nuts connecting the TB to air intake chamber and the fourth is near the firewall (hidden from plain view). One hose at the bottom can be loosened when the TB is removed.
15. Air-intake chamber [AIC] removal. Disconnect all the hoses (pre-mark) and connectors. Undo the nut holding ground wires on the passenger side of the AIC. Loosen the bolts holding the AIC to the engine block.
15 continued (b)... the hardest step is to loosen the 14mm hidden bolt. Locate the black metal hook [#1 engine hanger] near the firewall on the passenger side of [AIC]. You have to squeeze 14mm small socket and drive in there. The trick is to loosen it enough, while still allowing the socket to be removed. If the spin the bolt too much the head will stick out too far and you will not be able to remove the socket. Now you can struggle with finger to undo the rest or use a wrench [or thin gear head] to undo the rest. By loosing the bolt, the head will come out enough to clear the "U" of the engine hanger.
15 continued (c): Remove the bolt holding the PS pressure tube near firewall.
15 continued (d): Lift the [AIC] up and partially out. There is yet another ground cable at the back tied by a screw.

Cleanup time>> make sure your work environment is dust free and clean. Use the Shop vac to clean up the head area. In my case the harness box had crumbled. Vacuum and vacuum again.

16. Disconnect the fuel pressure line. Be careful as there may be a bit of fuel spill ... no open flame etc. In the engine bay way below the brake booster is the fuel quick connect. The cover is an upside down "U" shaped plastic. Squeeze the two sides and lift the cover off. Twist the pipe going towards the engine by half a turn and the pipe will separate. [as long as battery is disconnected and the key is removed the pump can not come on].

17. Start disconnecting the hoses and connectors to the intake manifold assembly [IMA]. Mark them. Note, some of the hoses may already be free from the far end.

18. Remove bolts of the top engine mount holding down the water outlet. Remove all bolts and the nuts on the studs. Note few bolts are short.

19. Before lifting off the IMA clean the area. Lift the IMA and with six clean rags stuff the intake holes ... anything that goes there will be impossible to extract.

20. Disconnect the connectors from the sensors. My clips broke and the harness had to be replaced. You will need 27mm open ended wrench or adjustable wrench. You can easily replace both sensors without removing the hose.

21. I had to struggle to release the harness from the driver side of the engine. The trick is to lift the lock towards the wire (away from the engine) and slide towards the cabin. I found it easier to attach the wires to the sensor and then thread the connector. Remember to snap on the harness stand-off as that will lift the wire of the hot surface.

Disassembly is complete.

Reassembly is much easier. Just reverse the steps and use new gaskets. There is a channel for coolant and if the gasket is worn/bad, you can get coolant in the intake. OEM gaskets are not soft/rubbery.

Dont forget the hidden bolts and ground wires.

Line up the wiper blades with the masking tape and toque down the holding nuts.

Tighten the coolant drain plugs. 1:1 mix ratio is not necessary {in fact a bit more water is preferred ... look at the mix ratio on the bottle**. Start by making a 1:1 mixture and top up with just water. Remember to add the mix in the overflow reservoir ... you dont want to top it with just water. It may take a day or two to have the system full or purged of air. Remember to run the heater too.


Safety Check: Check that the fuel connector does not leak.


Ref: Look up the DIY for coolant replacement and IACV cleanup thread.

Shortcuts: I was assured you need not remove the wiper motor/cowl. I needed to paint the faded plastic so I went ahead and removed it. I think the access is much easier and my hands are large .. so very well worth it.

Extras: My CEL only complained about one sensor, but I went ahead replaced both. Some suggest that the bypass hose should be replaced ... well mine looked in good shape and I decided not to touch it.
The wire carrier was in bits and pieces for me. Per-suggestions I have used high temp loom and suspended it by a bridge made out of coat hanger.

Torques:
IMA hold down 11ft-lb
AIC hold down 32 ft-lb
Engine mount long bolts 47 ft-lb
Engine mount short bolt 23 ft-lb
Wiper arm nut 18-lb-ft. S

Salim
Salim, I have to change my valve cover gaskets. I have to do same DIY like knock sensors. I don't have any Cel for knock sensors. Should I replace the knock sensors, harnesses, etc. since I have to go through it. How about the AIC removal, should I have to remove completely to do the rear valve cover gasket which is leaking now. Any suggestions greatly appreciate.
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Old 04-05-13, 07:22 PM   #50
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Originally Posted by gazi001 View Post
Salim, I have to change my valve cover gaskets. I have to do same DIY like knock sensors. I don't have any Cel for knock sensors. Should I replace the knock sensors, harnesses, etc. since I have to go through it. How about the AIC removal, should I have to remove completely to do the rear valve cover gasket which is leaking now. Any suggestions greatly appreciate.
If you have 130k+ miles and you plan to dig all the way to get to the harness, I would suggest replace both the knock sensors. The gaskets, coolant, harness and time will all add up enough to absorb the extra for the sensors.

Back to valve cover ... I think you would stop quite a few steps short (and replacement of gaskets). So I would suggest do the minimum.[Note: Since I have done the valve cover gasket replacement, I cant say which is the last step.]

Bottom line: You will have to make the call.

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Old 04-05-13, 09:44 PM   #51
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My RX has about 130k mileage and I think I should replace both sensors also. Thanks for your quick reply.
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Old 04-16-13, 01:44 PM   #52
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Quote:
Originally Posted by salimshah View Post
If you have 130k+ miles and you plan to dig all the way to get to the harness, I would suggest replace both the knock sensors. The gaskets, coolant, harness and time will all add up enough to absorb the extra for the sensors.

Back to valve cover ... I think you would stop quite a few steps short (and replacement of gaskets). So I would suggest do the minimum.[Note: Since I have done the valve cover gasket replacement, I cant say which is the last step.]

Bottom line: You will have to make the call.

Salim
Hi Salim, What sizes of torx socket you used for AIC removal from IMA (attached picture with red circled)?
For remove the front valve cover I saw about 5 stud bolts (pictures with red circled). What kind of tool you used for remove those bolts? Can you explain it to me please?
What is the parts number for harness hidden black plastic cover at the top of IMA picture with green arrow.
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Old 04-16-13, 02:08 PM   #53
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The big red-circle allen-headed bolt (there are two of them) are 8 mm. The smaller ones you circled in red do not need to be removed, as I recall, but in my case the heat insulator literally fell apart and so I don't know whether those bolts would need to be removed under better circumstances. The plastic box marked by you in green acts as a heat insulator for the wiring harness. I am told (but have not confirmed) that it is not separately available - you have to buy the wiring harness. If you learn differently, please let us know.
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Old 04-16-13, 02:38 PM   #54
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The little two circled in red, do need to be removed. You will need a Torx E6 (external).

Like Jab mentioned, if the heat insulator falls apart you won't need to be remove them. But, if the above picture is of your RX300, then you heat insulator look's like it's in good shape and you will need to remove the two bolts.
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Old 04-16-13, 03:05 PM   #55
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Thanks Hyper and Jab. It is my RX.
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Old 04-16-13, 05:05 PM   #56
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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 $$$$.

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Old 04-16-13, 05:29 PM   #57
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Quote:
Originally Posted by salimshah View Post
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
Thanks Salim. If I cannot use my old wire loom and how about this ( what sizes should be good 1/2" or 3/8):


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Old 04-16-13, 06:37 PM   #58
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1/2" will be better as you have no restriction to go through. Just make sure the loam has a split, you will not be able to thread it if the sidewalls are intact.

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Old 04-16-13, 07:12 PM   #59
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Thanks. I will make sure it. I will buy this one: http://www.summitracing.com/parts/rf...Fcuj4Aod6EIAgg
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Old 04-17-13, 10:08 AM   #60
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Question: On the rear valve cover, the wire loom for the fuel injectors is held in place by two nylon clips. How do you remove those?
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