2000 Rx300 Awd...not Shifting To Overdrive When Car Warms Up

[wflp1503]

2000 RX300 AWD with 61K on it.

Each morning when I start the car and put it on road immidiately, it runs smooth like it used to be. Gear shifts up all the way to overdrive while speed goes up. At 50MPH, the teco shows 2000RPM which is normal.

But it will last for only couple of minutes.Once I slow down then speed up again it won't shift to the overdrive back no matter how fast i go. That's about 2600RPM at 40MPH, 3500RPM when I drive at 60MPH. MPG drops to 14MPG from about 17MPG(suburban local drive) sicne two weeks ago.It normally happens when the collant tempracture reachs normal(take about 2 minutes). When it happens someehow the engine lucks of power a little bit ---- the idle is still smooth and steable, no engine knocking was heard even step on gas hard.

The check engine light has been on for a while (7 or 8 of months say). The car was running fine untill recently...I took it to autozone, the scanner shows P0171 (bankone too lean) and P0330 (knock sensor or circuit out). I switched the MAF with my 2000 Avalon (same engine) and the P0171 has gone, but P0330 remains.I also had the transmission flushed at Firestone at $200.

The other day I have a transmission shop scaned my car use there $6000 scanner....no transmission error code, P0330 is the only one can be found.

I also took it to 3 workshops, someone says it was due to a bad timeing belt replacing work, timing belt/water pump needs to be replacd again. Another guy from another garage told me the engine might be missfire (he did a test drive only, no tools used.He draws the conclusion based on the lack of power when press gas.).

I also called my local Lexus dealer. They told me the chance of knock sensor going bad is small...they only carry ONE knock sensor in stock , that kind of proved what they said....also, from this forum and someother forums, people also mentioned that knock sensor wires could go wrong...

I was trying to purchase a knock sensor harness but was told "no such thing available" :( Any thought?

Need some suggestion/diagnost before heading garage spending $600 to $1100(this is what dealer told me if they need replace both knock sensors)

:(

Any comments will be highly appreciated!!

[mehullica]

PO 330 will keep the trans from going into overdrive. I would replace both knock sensors and the sub harness. The harness will go from the knock sensor the just past the thermostat housing. The dealer can get it. I've replaced both sensors and harness for about $600 at a CA dealer.

[wflp1503]

PO 330 will keep the trans from going into overdrive. I would replace both knock sensors and the sub harness. The harness will go from the knock sensor the just past the thermostat housing. The dealer can get it. I've replaced both sensors and harness for about $600 at a CA dealer.

Thanks for the quick reply!

I will check another dealer see if they have the harness...may i ask how much you paid for the harness itself?

Here is the quote from my dealer:

$190 X 2 Knock Sensor

$130 intake manifold gasket

4.5 Hours of labor

Coolant refill

plus tax is how the $1100 comes. I am at north burb of Chicago.Looks like my dealer is kind of !Removed!...

And they refused to do the work without conclusion the problem themselves. To get the code scaned will cost me $120. I have heard horrible stories that similar problem turns out a transmission replacing work at $4000 to $6000 also need leave the car there for 10 days.

[wwest]

PO 330 will keep the trans from going into overdrive. I would replace both knock sensors and the sub harness. The harness will go from the knock sensor the just past the thermostat housing. The dealer can get it. I've replaced both sensors and harness for about $600 at a CA dealer.

Thanks for the quick reply!

I will check another dealer see if they have the harness...may i ask how much you paid for the harness itself?

Here is the quote from my dealer:

$190 X 2 Knock Sensor

$130 intake manifold gasket

4.5 Hours of labor

Coolant refill

plus tax is how the $1100 comes. I am at north burb of Chicago.Looks like my dealer is kind of !Removed!...

I would try, first, simply disconnecting both knock sensors. It sounds as if one or both are continuously sensing engine knock which will result in a rich mixture and poor, slow, upshifts and quick downshifts under load. Your 2000 has the earlier "resonant" knock sensor versions making it unlikely the ECU will "know" that are disconnected.

And they refused to do the work without conclusion the problem themselves. To get the code scaned will cost me $120. I have heard horrible stories that similar problem turns out a transmission replacing work at $4000 to $6000 also need leave the car there for 10 days.

I would try, first, simply disconnecting both knock sensors. It sounds as if one or both are continuously sensing engine knock which will result in a rich mixture and poor, slow, upshifts and quick downshifts under load. Your 2000 has the earlier "resonant" knock sensor versions making it unlikely the ECU will "know" that are disconnected.

[mehullica]

If the sensor is disconnected, the ECU will know right away. As soon as the engine is started it will see not input signal from the knock sensors and trip the CEL light.

[wflp1503]

PO 330 will keep the trans from going into overdrive. I would replace both knock sensors and the sub harness. The harness will go from the knock sensor the just past the thermostat housing. The dealer can get it. I've replaced both sensors and harness for about $600 at a CA dealer.

Thanks for the quick reply!

I will check another dealer see if they have the harness...may i ask how much you paid for the harness itself?

Here is the quote from my dealer:

$190 X 2 Knock Sensor

$130 intake manifold gasket

4.5 Hours of labor

Coolant refill

plus tax is how the $1100 comes. I am at north burb of Chicago.Looks like my dealer is kind of !Removed!...

I would try, first, simply disconnecting both knock sensors. It sounds as if one or both are continuously sensing engine knock which will result in a rich mixture and poor, slow, upshifts and quick downshifts under load. Your 2000 has the earlier "resonant" knock sensor versions making it unlikely the ECU will "know" that are disconnected.

And they refused to do the work without conclusion the problem themselves. To get the code scaned will cost me $120. I have heard horrible stories that similar problem turns out a transmission replacing work at $4000 to $6000 also need leave the car there for 10 days.

I would try, first, simply disconnecting both knock sensors. It sounds as if one or both are continuously sensing engine knock which will result in a rich mixture and poor, slow, upshifts and quick downshifts under load. Your 2000 has the earlier "resonant" knock sensor versions making it unlikely the ECU will "know" that are disconnected.

Could you describe how to disconnect the knock sensor without open the intake manifold??I tried to figure which cable is which, but couldn't find any clue :(

Thanks!

[mehullica]

kNOCK SENSOR HARNESS PART NUMBER=82219-07010. Disconnecting the harness will not help, if you want to try it look near the thermostat housing. There's a connector that runs under the lower intake manifold. Thats the one that runs to the knock sensors.

[wflp1503]

kNOCK SENSOR HARNESS PART NUMBER=82219-07010. Disconnecting the harness will not help, if you want to try it look near the thermostat housing. There's a connector that runs under the lower intake manifold. Thats the one that runs to the knock sensors.

I guess I have found the knock sensor cable: it does have a connector connect to the main cable/wires although it is very hard to be seen, also hard to be reached by hand.

Here is the weird part(something new):

When I look for the knock sensor wire, I tried to look into the place under the intake manifold(from the passenger side right over the belt between two group of wires go to the two side of the engine). Superisly I found it looked there are some "cotton fiber" like stuff inside....I used a stick and a small hook successfully pulled out some (in size of two cuffee mug). It is in pink color, mixed with some little green/red thread and none of them are longer than 1/3 inche, as well as some brown dots...I seriously doubt it was some engine part????It looks like a bird net materials....

Any one seen the same thing when you remove the intake minifold completely?

[jgr7]

Sounds like some mice moved in and most likely ate the knock sensor wiring. You should take off the intake or have it done and repair the wires.

Jeff

[wflp1503]

Sounds like some mice moved in and most likely ate the knock sensor wiring. You should take off the intake or have it done and repair the wires.

Jeff

****

I googled this. What I found is that mice like the newer Honda pilot's knock sensor harness the most since the formula of the plastic includes soy...it sounds funny but might make a lot sense on this case too.

****

I tried to disconect the knock sensor connector but no lcuk due to the space is too narrow and it is pretty tied. Looks like I have to pay some one open it up no matter it is the sensor's problem or wire damage. I called around, there is a garage would like charge me $225 (3 hours labor) to get both knock senser replaced.Sounds resonable.

I ordered two knock sensor from www.rockauto.com. They have it for around $120. I called them they told me the brand is "standard" but actually there is a "denso" marked on the part. I kinda trust them since I have ordered from them couple of times never had any problem...price is unbeatable

Also get a set of intake manifold gasket from them, $55.

Found the knock sensor harness from my dealer, it is only $36+tax!!Thanks mehullica!!!

****

Now I will wait for my parts arrive then heading the garage.I will wait there to see them open it up, hope the mouse 's gone :(

[wflp1503]

got the parts: the knock sensor was packed in a small box which has "standard" printed on it. Open it up, as they claimed, there is a "denso" printed on the parts. Looks in decent quailty.

The gasket arrived too.

[wflp1503]

got the parts: the knock sensor was packed in a small box which has "standard" printed on it. Open it up, as they claimed, there is a "denso" printed on the parts. Looks in decent quailty.

The gasket arrived too.

OK, the problem is gone.

They opened it up, found more fabric stuff under the mainfold intake. Mechanic said there must be some "visitors" been here and try to make it home there...we carefully checked the wire, nothing's broken though.

So they went ahead replace two knock sensors and the wire. They said there is another gasket needs to be replaced, it cost around $30.Fortunately their supplier had the part delivered in just 30 minutes while they are working on the engine.

They got the whole work done in about 2.5 hours.

When I start the car I was holding my breath. The check engine was not on...I drove it on road, step on the gas, and the transimission shifts all the way up to overdrive. Now the rpm is around 2100 at 50 MPH, and I got about 16.5 MPG local...not great, but I am already very happy about the result.

Till today it has been more than two weeks and I've put around 600 miles on it, so far so good. THE HEADACHE IS GONE!

Cost:

Knock sensor: from rockauto.com, brand is "standar" but they are actually "denso", $120X2= $240

Intake Gasket: $70 from rockauto.com

another gasket: $30 from garage's parts supplier

knock sensor wire $40 from Lexus Dealer

Labor: $225

Total: $600 roughly

Thanks for all the replies,

gl

Leo