Droning rumbling sounds issues (1 Viewer)

[Wadepat2]

I have searched and read tons of post but still not sure where I should start. Quick summary. I am an American currently living in Dubai. Purchased a GCC spec 1999 LC 4.7. I plan to bring it back to US after the 25 year mark when I return home. I have been replacing everything with OEM parts while I am here. Parts are easy to find and labor is cheap. Can only do so much work myself here since I am in parking garage.
My plan is to make it as close to new as possible . Since I bought this LC and not new car I have plenty of extra money to do that. I already have more money in parts than I do in the cost of the LC but Its worth it to me. 215 km (133k miles) on the clock. All stock except for Toughdog shocks.

Problem: At Idle in Park, Drive, N, 30mph or 80mph, AC on or off doesn't matter. The rpm hits a sweet spot and I get an annoying deep bass resonance drone. Sometimes I get small vibration at idle also.

Would like to get this sorted before January when I plan to add TRD SC.

This issue is small but still annoying. I haven't replaced any parts because of the drone but was hoping it would get fixed along the way. It was time for plugs and I had a coil fail, so I replace plugs, coil packs, air filter, fuel filter, and MAF. (all OEM) Also cleaned Throttle body. I even found an installed that goofy weight thing on frame.
Runs strong, only very small vibration sometimes at idle and the drone comes and goes. Seems to be worse when engine temp is lower on the gauge. (first start up or after long highway run) Could just be I don't hear or feel it once the viscous Jet engine sounding fan is running nd engine idles up.

I am leaning toward injectors maybe need cleaning or exhaust?

I have no CEL or anything. I tried to connect to Torque app to check temps since it seems more to happen when engine isn't up to temp but the OBD2 port doesn't connect to Torque since (I assume) it isn't actually OBD2 just has the port. The blue tooth dongle connects but doesn't see ECU. If use the string I have seen on other forums for this issue Torque app sticks at "Checking model"

I have ordered a cable to try and connect Tech stream which I assume should work fine. Wont be in until next week and I have no idea how to use it.

I don't mind throwing parts at it since I am replacing almost everything I can anyway. Everything underneath is almost new already so fire away. haha If cant pin point it I will have injectors cleaned before TRD SC goes in and then replace stock pipes with cats with OEM. Would prefer to actually find the issue though.

Thanks for the help. Hoping to create a post for when I bring SC back to install.

 

[Greenbean]

Hmmm...

Well I would think maybe an engine mount was worn and the vibration it causes when "flexing" more than when new.

Good luck tracking it down though...

Subd for the updates!



Guess I need to say congrats on scoring a GCC spec rig too!!!

Those get locker options in the rear also?

 

[Wadepat2]

Hmmm...

Well I would think maybe an engine mount was worn and the vibration it causes when "flexing" more than when new.

Good luck tracking it down though...

Subd for the updates!



Guess I need to say congrats on scoring a GCC spec rig too!!!

Those get locker options in the rear also?

Thanks. The boom is annoying. Guess it could be a mount. Will definitely take a look.

Rear has factory elocker and I added front TJM air locker. Not really needed for sand driving but will use once back in US and wanted to strengthen front diff.

 

[jerryb]

I'd be looking for a hole in the the exhaust. Being in sharjah or close to to it I'd just buy all new. Both engine mounts and the transmission mount also.
Personally, If there was a walk up window to buy parts my bank account would really suffer. I'm little envious. I worked over there to for a time. I'm always trying to get back.

I have had bluetooth readers not work on me right out of the box- ELM. The ten dollar ones specifically.
I went back to the veepeak OBDcheck vp11. That one works well for 2006 LC and also a newer lexus.
Techstream will work fine with more of a learning curve. I use obd fusion which is slightly easier than TP. Also the toyota add ons in obd fusion are worth it.

 

[Wadepat2]

I'd be looking for a hole in the the exhaust. Being in sharjah or close to to it I'd just buy all new. Both engine mounts and the transmission mount also.
Personally, If there was a walk up window to buy parts my bank account would really suffer. I'm little envious. I worked over there to for a time. I'm always trying to get back.

I have had bluetooth readers not work on me right out of the box- ELM. The ten dollar ones specifically.
I went back to the veepeak OBDcheck vp11. That one works well for 2006 LC and also a newer lexus.
Techstream will work fine with more of a learning curve. I use obd fusion which is slightly easier than TP. Also the toyota add ons in obd fusion are worth it.

Thanks Jerry, no exhaust holes. Just went through yearly inspection with the emissions stuff etc . It's also always been crazy quiet. Kind of wish It had a little more sound. Will try the mounts for sure next. Will still robably go ahead and swap complete OEM exhaust also in case cats are getting old. It's also the only thing with even a little surface rust. OEM is Cheaper than aftermarket here.
Yea my bank account takes huges hits here. Just to easy here .
Thanks for the tips. I did also try 3 different obd2 that I had working on other vehicles but no luck with this 99 port.

 

[2020 Rocks]

Do you still have the what is this connected to the frame?

Do you know what this is?

Wondering if someone can tell me what this is, besides being a rusty part. It’s located on the driver side on the frame. I think I’m getting some squeaky noise from it. I want to remove it off I can. Thanks in advance.

forum.ih8mud.com

 

[GTV]

Exhaust would be the first thing I’d look at as well… it still has both the muffler and resonator in place, correct?

 

[Wadepat2]

Exhaust would be the first thing I’d look at as well… it still has both the muffler and resonator in place, correct?

Yep all stock with the thing on frame. Two votes exhaust. Headed to check that out shortly. Really hoping that would be it but didn't notice anything before and it's super quite outside car

 

[Greenbean]

Just out of curiosity, have you been at the 30 mph, then shift into N, (scratch that) get to 40 then shift to N and see if while slowing down through 30 its there.

Just a way to help rule out trans and driveline stuff.

 

[Wadepat2]

Just out of curiosity, have you been at the 30 mph, then shift into N, (scratch that) get to 40 then shift to N and see if while slowing down through 30 its there.

Just a way to help rule out trans and driveline stuff.

I think I can rule most of drive line out. Does it in Neutral, drive while stopped and Park the most. Could it still posisble be trans related with thsie symptoms?

 

[Wadepat2]

Exhaust looks good. Just had underneath pressure washed so it's pretty easy to check. No leaks.. man the pipe is small where it Ys to muffler. Maybe cat is clogging?

Will clean throttle body better tomorrow.

Trans mount looks good but will change with engine mounts next I guess. I have to check my parts list. I think I changed trans mount when seals where done in transfer case.

 

[Greenbean]

I think I can rule most of drive line out. Does it in Neutral, drive while stopped and Park the most. Could it still posisble be trans related with thsie symptoms?

I highly doubt it,

When in neutral “technically” you have disengaged it.

yes it is all mechanically attached and things transfer but that really makes me wonder if you’re dealing with a motor mount of sorts or maybe a couple of them.

If that’s the case then it’s basically a coincidence right? that what you hear or feel at 30 miles an hour and at 60 is purely coincidental because he just happen to hit the frequency but it’s able to transmit on if that makes sense.


The thing that really pointed me to a motor mount(s) or possibly a transmission mount(s) is that because the bell housing is bolted to the engine block, if you were to jump in a brand new one or even a brand new Lexus when the engines running you feel virtually nothing now some of the newer cars I have seen have a vacuum assist pulse that works against the engine vibration so I think you’ve got a mount issue somewhere.


To get even more technical, have you basically gotten a chassis ear or a stethoscope with a long screwdriver handle and had somebody duplicate it inside the vehicle and you can be outside the vehicle in touch certain areas of the firewall the engine compartment and basically listen for something different?

Also you actually don’t even need a stethoscope if you’ve got a really long screwdriver (like 2’ or more) hold that screwdriver handle to your ear and touch it down to something inside the engine bay and you can tell differences.

 

[RND1]

Do you still have the plastic shroud that covers the engine? If so, remove it and report back. The foam deteriorates causing vibration at idle.

 

[Wadepat2]

Do you still have the plastic shroud that covers the engine? If so, remove it and report back. The foam deteriorates causing vibration at idle.

Sure do. It's easy enough to remove. I'll try it.

 

[mitchjohnson000]

Wait, you have LHD 2UZ and a vacuum brake booster? I'm jealous.

 

[Jae]

I have been having the same issue. (My LC is 2000)
I replaced spark plugs and all mounts (engine and transmission) with OEM ones, fuel filter, fuel pressure regulator, and cleaned the throttle body. I don't have the engine cover. At Idle in N my LC is fine, but in the Drive, the rpm drops from 700 to 600 and I get an annoying deep bass resonance drone as well.

If you see the attached PDF, there are some suggestions.
I saw another suggestion in this forum that the rpm can be increased by adjusting TB setting, but I couldn't find it anymore.

If you find the solution, please keep us updated.

 

[hoser]

Sure do. It's easy enough to remove. I'll try it.

View attachment 2812251

This is quite a rare 100 (well, at least outside GCC). Most people won't know so I'll clue them in.

-Yes, the standard brake booster is stock
-Round charcoal canister (not better, nor worse, just different)
-Cyclonic Airbox with washable air filter (better, for sure)
-You can't see this but this vehicle likely doesn't have O2 sensors. (good or bad, depends on how you look at it) but because of that, you might have issue with installing a TRD SC.

@Wadepat2 You can actually import this into the US now. You don't have to wait until it's 25 years old.

 

[Wadepat2]

This is quite a rare 100 (well, at least outside GCC). Most people won't know so I'll clue them in.

-Yes, the standard brake booster is stock
-Round charcoal canister (not better, nor worse, just different)
-Cyclonic Airbox with washable air filter (better, for sure)
-You can't see this but this vehicle likely doesn't have O2 sensors. (good or bad, depends on how you look at it) but because of that, you might have issue with installing a TRD SC.

@Wadepat2 You can actually import this into the US now. You don't have to wait until it's 25 years old.

Thanks for answering the usual questions .
I'll check today for oxygen sensors. Never thought about that.... Crap ,might have a very expensive SC I can't use. Didn't even get it yet but good to know before I bring it here. Any more info you can share?

 

[Wadepat2]

This is quite a rare 100 (well, at least outside GCC). Most people won't know so I'll clue them in.

-Yes, the standard brake booster is stock
-Round charcoal canister (not better, nor worse, just different)
-Cyclonic Airbox with washable air filter (better, for sure)
-You can't see this but this vehicle likely doesn't have O2 sensors. (good or bad, depends on how you look at it) but because of that, you might have issue with installing a TRD SC.

@Wadepat2 You can actually import this into the US now. You don't have to wait until it's 25 years old.

I did read that I could import now but it would be easier after 25 yrs. Since I need it here for another 3-4 years it works out well.

Confirmed no O2 sensor after the cats.... Not sure where to go from here. Will call some tuners and see what's possible with the piggyback unichip that's coming.

 

[hoser]

Any more info you can share?

No expert on the matter but having no O2 sensors means it is an open loop system. In a closed loop system, the ECU gets immediate feedback from the O2 sensors to alter it's fuel maps and timing. In a open loop system, the ECU just does what it wants or is programmed to do. Tuning an open loop system will likely be more difficult to do.

However, you can't be the first person out there to do it. I think 2001+ GCC 100's went to closed loop system (w/ O2 sensors).