Hello and...Throttle body buzz/whine (2 Viewers)

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Jan 24, 2023
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Castle Rock, CO
Hey all, I'm hailing from south of Denver with an '01 LX470. It has been the subject of a few threads on here I believe, from the previous owner a few years ago. I have been an occasional wall fly for the vast knowledge here over the years, for my '93 LC and now this beast. But figured I'd join in the fun instead'a just listening from the stands.

The LX470 has been having issues, random total power loss with rapid acceleration, randomly losing acceleration capabilities at all with the sputter-putt affect, randomly occasionally dying, and finally last night died and would not start again. All issues I have found on here. All very fun issues on the highway...or in intersections...or in parking lots on 10 degree nights... finally had to have it towed back to the house. Being my wife's daily driver, it's time to address the issue.

That lead me to some testing, and so far the APPS tests good, haven't gotten to the TPS yet. The garage is like 40F and still wet with (barely) melted snow puddles....I don't wanna! hehe.

As I was going about this, the second time I turned the key to on position and moved to the front I heard a really ugly high pitch buzz/whine coming from the throttle body. It got louder as I tugged on the throttle cable. The Throttle plate was engaging, but it didn't appear to like it very much. Then the noise stopped and TP stopped responding to the cable.

A few minutes later, I tried key-on position again and got the buzz, but it never stopped. Just kept on hating being a Throttle Body and screaming about it. Again, throttle plate responded to cable, but it screamed progressively louder with more pull.

I think it seems to be coming from the Motor assembly side of the TB . With the help of a listening stick, it seemed louder on that side. I have seen a couple write ups on different TB's that mention the gear/clutch causing issues that sound like this. Has anyone here seen (heard!) this problem on the 100 series?

I am highly considering just replacing the whole TB but feel like if I can just do the motor confidently that I might rather do that. It sure is a little less, but is it a sure thing?
Any info or experience would be great. Thanks for all your wisdom mudh8ers!!
 
Hey all, I'm hailing from south of Denver with an '01 LX470. It has been the subject of a few threads on here I believe, from the previous owner a few years ago. I have been an occasional wall fly for the vast knowledge here over the years, for my '93 LC and now this beast. But figured I'd join in the fun instead'a just listening from the stands.

The LX470 has been having issues, random total power loss with rapid acceleration, randomly losing acceleration capabilities at all with the sputter-putt affect, randomly occasionally dying, and finally last night died and would not start again. All issues I have found on here. All very fun issues on the highway...or in intersections...or in parking lots on 10 degree nights... finally had to have it towed back to the house. Being my wife's daily driver, it's time to address the issue.

That lead me to some testing, and so far the APPS tests good, haven't gotten to the TPS yet. The garage is like 40F and still wet with (barely) melted snow puddles....I don't wanna! hehe.

As I was going about this, the second time I turned the key to on position and moved to the front I heard a really ugly high pitch buzz/whine coming from the throttle body. It got louder as I tugged on the throttle cable. The Throttle plate was engaging, but it didn't appear to like it very much. Then the noise stopped and TP stopped responding to the cable.

A few minutes later, I tried key-on position again and got the buzz, but it never stopped. Just kept on hating being a Throttle Body and screaming about it. Again, throttle plate responded to cable, but it screamed progressively louder with more pull.

I think it seems to be coming from the Motor assembly side of the TB . With the help of a listening stick, it seemed louder on that side. I have seen a couple write ups on different TB's that mention the gear/clutch causing issues that sound like this. Has anyone here seen (heard!) this problem on the 100 series?

I am highly considering just replacing the whole TB but feel like if I can just do the motor confidently that I might rather do that. It sure is a little less, but is it a sure thing?
Any info or experience would be great. Thanks for all your wisdom mudh8ers!!
Correction...It doesn't get progressively louder, it adds a crunchy buzzy sound that "moves" with the cable
 
It sounds like the throttle motor might be going out.

Yes, there is an electric motor on the early 100's that open and close the throttle plate. The throttle cable at the throttle body is connected to the APPS. If the APPS or throttle motor dies, the throttle cable can engage the throttle plate in the last 10% or so of throttle cable travel through he APPS linkage. The TPS is there to check that the throttle motor is opening the throttle plate.

I have experienced the throttle body motor buzzing. A new (well, good used) motor and TPS fixed it.
 
It sounds like the throttle motor might be going out.

Yes, there is an electric motor on the early 100's that open and close the throttle plate. The throttle cable at the throttle body is connected to the APPS. If the APPS or throttle motor dies, the throttle cable can engage the throttle plate in the last 10% or so of throttle cable travel through he APPS linkage. The TPS is there to check that the throttle motor is opening the throttle plate.

I have experienced the throttle body motor buzzing. A new (well, good used) motor and TPS fixed it.

Yep that's the noise. Thanks for the input! now just to decide if I want to do the whole thing or just the motor. Thanks again!
 
I have the buzz here as well, looking at the motor/APPS/TPS components: they add up to significantly more than I found the part at McGeorge (under $500 shipped).

Haven't had a shut down yet since the buzzing started about six months ago, but did have a CEL two years ago during negative temps, which resetting the battery fixed.

I haven't pulled the throttle body yet so am wondering, is there a gasket between the two plates? I'd assume on this its machined aluminum surfaces mating to keep it simple.
 
OK I ordered a full throttle body assembly and will report back. Am hoping it helps smooth idle a bit, eliminates the buzzing coming from the motor unit (which isn't bad but about as loud as the charging noise the brake booster makes) and makes sure I don't have APPS or TPS failures which cause issues in cold weather. I haven't had one in quite some time but am not about to find out.
 
I am fighting this issue as well and am in the process of replacing my TB assembly.
 
Alrighty,

Wasn't the throttle body. Discovered the whine only occurs when the air conditioning or heater is on ... thoughts?
 
When your heat is on is your defrost also? What I'm getting at is - is your AC compressor clutch engaged when the whining starts?

When I did my timing belt recently I ended up pulling and replacing my AC compressor clutch bearing as it was more or less spinning freely. When I had it removed I did notice it was a little scratchy. My vehicle came from Scottsdale so in terms of AC usage for the mileage... its probably way up there.
 
I noticed that I didn't update after I replaced the Throttle body here as I mentioned prior that I would. I did replace mine with an all new unit, hoses, gasket, etc. No change in performance or whine, just lighter wallet.
 

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