CaltonB

I just wanted to see if anyone had any idea what this may be, the vibration can be felt in the steering wheel and the seat faintly... the car also has a deep idle noise, all of this disappears once accelerating or in neutral. My first instinct is the motor mounts because the vibration disappears once in neutral but the deep idle noise makes me wonder of something else. I have a 2002 rx300 awd with about 130k. It accelerates fine, shift is fine there are no lights and nothing pops up when I hook up an obd2. I thought it could possibly be the spark plugs or the timing as well but the fact that the vibration totally disappears once I put it into neutral gear or accelerate leans more towards mounts doesn't it? Not sure what to make of the deep idle noise.. it doesn't sound like a dodge hemi or anything but it sounds deeper then this small engine should make. The idle is around 800ish and doesn't really drop or go up significantly but it does seem to fall occasionally then jump back up. I am not sure if this is just normal for this car and mileage regarding the rpm slight fluctuation.

ukrkoz

Engine mounts. In neutral, transmission is taking virtually no power demand from ICE, hence it runs lighter.

CaltonB

Would that also be related to the deep noise I get at idle? I thought it was an engine or exhaust related noise but could it be the vibration of the engine itself? I've also noticed at times on a cold start the rpms are very low (about 100-200) almost to the point where I can't tell if the car is off or on until I either rev it a bit or drive it and it eventually settles back at 800. It has never shut off or stalled, there are no lights but I feel like I should be wary of this.

artbuc

ukrkoz

Bad engine mounts/trannie mounts ALWAYS produce rambling noise due to vibration kicking directly into body and frame.
How your car didn't stall at such low RPMs I have no idea but artbuc has very valid suggestion.
As a side note, I did ALL power train mounts on my then 2012 Highlander Hybrid. They were all in various stages of deterioration - at only 90K miles.

CaltonB

Thanks for the advice. I will try to clean the IAC valve myself as this seems the easiest to diy and the cleaner is like 6 bucks. I also am not sure how it has not stalled at the 200 rpm start... just wanted to add that it only does this on a warm start for some reason and as soon as I rev it a bit it is back to the 800+ regular rpms. I've never driven the car and the rpms dropped to this level.

CaltonB

Well I cleaned the IAC Valve and the throttle body (which both looked pretty clean before hand). I noticed right off that the low rpm startup issue is gone and the car seemed to have more acceleration and better mpg but still had the vibration issues in gear. I drove about 100 miles on the freeway until check engine and vsc lights appeared on the dash. I ran the reader and got the code "P0330 KNOCK SENSOR 2 CIRCUIT". Is this related to my issue? Also not sure why the vsc light appeared... I read up a bit on this forum about P0330 and am not clear on what this issue is even after scanning.

ukrkoz

https://www.clublexus.com/forums/rx-...placement.html

2013FSport

iTrader: (2)

Open the hood, engine on, brakes applied, and place it in drive and apply some throttle. Perhaps 1/4 throttle maybe more?? If the engine jumps around moving inches from its original location you likely have some mounts failing.

CaltonB

Is it at all possible that it could throw this error with these issues and not be the knock sensor? I am getting extremely high quotes on changing this part... is $800 dollars for both reasonable?

CaltonB

I am still wondering if something else can trigger the knock sensor code before I take the plunge and have a mechanic change it. I've talked to many mechanics and they have mostly said the knock sensor is extremely rare to go bad and that it could literally be anything causing this to happen and that the sensor could be doing its job. I am now wondering if my ac compressor could be the cause because it does seem to be failing slowly, it blows cold air but makes a loud screeching noise when it's running due to the clutch sticking. Could fixing my ac resolve this issue? Turning on the ac also contributes to the vehicle vibrataion at idle greatly. I also have a bad blower motor i think because i hear the flapping noise inside the cabin when I turn on the ac. I don't think this would have any real impact on the cars performance but I notice that I hear this noise when the ac is not turned on as well. It sounds like a slow spinning fan coming through the center ac vents. Could this be the blowmotor? I thought it would not make any noise if I turned off the ac.

99rx

iTrader: (6)

If the code came on after cleaning the IACV, then I would tend to associate it with what you did. I am having the same issue you are with my old RX I gave to my cousin. See one of my threads. Everybody has recommended cleaning the IACV, but like yourself, it changed nothing. I changed the mounts with all OEM prior to giving it to her with no change at all. Really frustrating because the entire cabin vibrates. Hope you have success figuring it out.

CaltonB

This is a relatively new purchase so I am guessing the code was cleared and just came on coincidentally after cleaning the IACV. The only thing that has changed driveability wise after cleaning it was it appears to have stopped starting at 200rpms (for now)... also the readout on the mpg shows 14.1 pretty much all the time as opposed to the 22 it used to show (I believe that 22mpg was inaccurate though.. possibly a computer error that corrected itself after I drove for a while). The car still has rough idles and the CEL comes and goes as it pleases. The only thing I can really pinpoint at this point is that the idle roughness is really prevalent when I turn the ac on and I am 100% sure the ac compressor clutch is sticking only reason it hasn't been changed already is because it is blowing cold air fine. I am wondering if changing the compressor will fix these issues as it is putting strain on the engine and possibly causing the knock sensor check light? I am speculating here but i'd hate to change the knock sensors to see the same light come right back on.

RXsassy

I had almost the same problem, except acceleration made it worse. Knock sensor was what auto zone said so took it to the mechanic and the drive shaft fell off when he did a test drive. Cost me 800$ to replace because they said they dont make the part for my 99 model.

CaltonB

Wow, that is crazy. I've never actually heard of a drive shaft just falling off like that especially after a test drive how bad was it? Were you experiencing vibration on initial takeoff? I had this issue with vibration at initial take off on my mercedes cls and it was the driveshaft bearing (which I got replaced right away). I am also experiencing some slight vibration on initial takeoff with this vehicle as well ( i must just have some crazy bad luck). The price they gave you to change the entire drive shaft is less then what I've been quoted by many of these places to replace the knock sensors still... I will look into the bearing but I guess this just confirms that literally anything can trigger the knock code. Half the battle is finding a competent mechanic out here because it seems like i'm having to help them figure out the issue.