Lexus 99 rx300 - sluggish acceleration - advice
 

Dear friends,
I have a lexus 1999 rx300 162k miles. Recently it had check engine lights for
1. System lean p0170
2. Knock sensor both banks, I think 330 and 325

I started hearing some mettalic knocking noise when I accelerate and vehicle is not able to deliver the full power. In addition to that, the power has become less it struggles to pick up when i pause in traffic lights. The last gear is not shifting, if I drive 70 mph the rpm is 4000+. Mileage has come down

My toyota mechanic said even if we fix knock sensors it won't fix. So I took to my another mechanic friend, he put new spark plugs and changed some knock sensors and now the lean system, one knock sensor bank issues are gone. But still it's sluggish. So he said he needs time, he is trying to change the vvti and do a last try.

I need your advice on whether I have to fix this, or should I get rid of it.

We don't know enough about the vehicle [current value, current condition, repair cost, how attached you are to your Rx, your desires to obtain a newer/different vehicle].
You may have to diagnose/fix the issues one at a time.
Knock sensor code will keep you in limp mode.
VVTi when malfunctions can rob you of power. Just make sure all 6 cylinders are working.

I would suggest using Lexus/Toyota specialist shop as your problems are related to electronic sensors.

Salim

You're new here, adding a couple of clarifications in case you do not know:

• The metallic knocking noise on acceleration is engine knock. That's what the knock sensors are for.
• "Limp mode" is a failsafe that the ECU will put the car in for some codes, including the knock sensor ones. While in limp mode it will run rough and will not shift into overdrive.

It sounds like the knock sensors were changed. Are there any codes now?

I'll 2nd that.
The knock sensors adjust the engine timing and it's needed or you get.... knocking. lol

I agree, one step at a time.
You will need a good tech with a scope to scan the cam sensors in real time while running Techstream and advance and retard the VVTi and watch the screen and response from VVti.
This will show the tech exactly where the cams are hitting and seen on the scope, at least that's how I did it.

If your tech can't do this he is flying blind and guessing on a huge repair since it's a big expensive job to start pulling VVT's when they haven't been properly tested & scoped first.

You will need a tech at a higher level and must have a scope and prove it before tearing down engine.

Note- the cam sensors will report cam position and vvti controls the cams advancing and retarding as seen on the scope.

Thanks for all your messages, advices, guidance. Updates below :

Engine Error Codes
1. System lean p0170 - Resolved
2. Knock sensor both banks, I think 330 and 325 - One is fixed.
The only EXISTING CEL Code is "p0325 knock sensor 1 circuit bank 1 or single sensor".

PART CHANGES
The mechanic replaced the knock sensors, harness, new spark plugs. He said he ll figure out the other issue after sometime.

DRIVING EXPERIENCE
Earlier the acceleration was slow while starting from 0 & it will produce some metallic noise when I accelerate more and the power delivered is less.
Now I dont see both the issues. But the high RPM issue exist
I drove at the highway; still the last gear is locked I feel. When I drive in 55 mph the RPM is 3300 & it keeps increasing; if I cross 60 it goes to 4000

Do you have a code reader?

Can you reset/clear the code and drive. Does the knock sensor error code, come back immediately? if not, then how is the drive?

Salim