Need Help Diagnosing Multiple Issues '02 Ls430

[Ancdmd]

I have some issues with my 2002 LS430 Ultra, and I've had multiple mechanics dragging their feet with resolving them. The car has 120k miles and has been well maintained. Timing belt, plugs, water pump, pulleys, tensioner, rear diff fluid at 105k. Just cleaned MAF and throttle body. Replaced ENTIRE front suspension last summer. Recent transmission full fluid flush with Amsoil ATF, been using full syn for motor oil, full syn in power steering.

1. The most annoying issue I have is a clinking noise that is most evident on the highway. I can hear it faintly at all speeds but it is loudest at higher speeds. It sounds something like engine knock or a loose heat shield, and is elicited when I barely have my foot on the accelerator and the car is slightly slowing down. Sounds like its coming from the trans area or closer to the motor. I had the heat shields removed from the y-pipe and the pipe is fine. No CEL has ever appeared. Techs looked at the car and either couldn't hear the noise or shrugged their shoulders. The noise is loud enough that even someone not in tune with my car would have no problem hearing it on the highway. I have noticed a few hard downshifts lately, but nothing consistent. We had the car on lift today and revved it and couldn't hear anything definitive. This problem showed up a couple months ago and has gotten more prominent since then. A few times when I gave it some good throttle at lower speeds to pass a car or something it gave me loud engine knock sound before a slightly delayed downshift, didn't seem right.

Here is a recording of the noise, it is sporadic throught but easily heard at 1:22-1:27 into the video:

2. For the last week the car idles low, around 450-500 rpm. This has occurred since I had the air conditioning compressor replaced last week. It goes up to 800 when the compressor is on. Otherwise the idle is smooth and the car runs well.

[landar]

As concerns issue 1, you might investigate the integrity of the transmission mount and engine mounts. Your car is at an age and mileage where the rubber bushings in these components might be cracked or separated. It is easy to miss with a simple inspection.

Issue 2, maybe IACV?

[1990LS400]

A number of people have said that the transmission mount is usually the first of the three mounts to go. There have been photos posted of transmission mounts that were in pretty sad shape at fairly low mileages - the rubber collapsed, severely cracked, and separated from the metal mount bracket.

The rate of wear on the mounts must vary a lot. I had the original transmission mount on my 2000 LS400 replaced yesterday at the 150,000 mile service - it looks like new ... no compression of the rubber, no cracking, no separation of the rubber from the bracket. I thought a new transmission mount might eliminate the very slight vibration I was feeling through the steering wheel at idle but it did not. But a new transmission mount was pretty cheap - $150 for an OEM mount including labor - and I sure won't have to be concerned about it again during the final few years of owning this car. My understanding is that replacing the two engine mounts is substantially more difficult and expensive.

[Ancdmd]

I forgot to mention that I did install a new transmission mount a month ago when I replaced the ATF. The old mount looked ok, and unfortunately installing a new one didn't make any difference.

[SW03ES]

My guess is a mount too...hard to tell the noise from the video, but I think I hear it...almost like something is binding?

[jaswood]

The only significance in the sound I hear is the change in tire noise as you drive over differing highway pavement sections. IMMHO the primary "mount" area, early failure, would be the top mount/cushion for the front struts, the rear diff'l mounts/cushions, and/or the outter rear suspension mounts/cushions.

The idle change is bothersome in that the engine ECU is programed to raise/keep the idle speed relatively constant with the on/off engagement, added load, of the compressor. It sound to me as if the compressor might be adding more load to the engine than the ECU is programmed to make up.

"Slugging" the compressor, liquid refrigerant returning to the compressor inlet due to a to high a refrigerant charge might do that. That may also be the clicking sound, the compressor clutch kicking in and out as a result of the overcharge.

The A/C indicator light should flash if the compressor, when the clutch is engaged, does not turn at a speed cognizant with engine RPM. I'm not sure what would happen if that was a temporary, intermittent, event.

[jaswood]

I have some issues with my 2002 LS430 Ultra, and I've had multiple mechanics dragging their feet with resolving them. The car has 120k miles and has been well maintained. Timing belt, plugs, water pump, pulleys, tensioner, rear diff fluid at 105k. Just cleaned MAF and throttle body. Replaced ENTIRE front suspension last summer. Recent transmission full fluid flush with Amsoil ATF, been using full syn for motor oil, full syn in power steering.

1. The most annoying issue I have is a clinking noise that is most evident on the highway. I can hear it faintly at all speeds but it is loudest at higher speeds. It sounds something like engine knock or a loose heat shield, and is elicited when I barely have my foot on the accelerator and the car is slightly slowing down. Sounds like its coming from the trans area or closer to the motor. I had the heat shields removed from the y-pipe and the pipe is fine. No CEL has ever appeared. Techs looked at the car and either couldn't hear the noise or shrugged their shoulders. The noise is loud enough that even someone not in tune with my car would have no problem hearing it on the highway. I have noticed a few hard downshifts lately, but nothing consistent. We had the car on lift today and revved it and couldn't hear anything definitive. This problem showed up a couple months ago and has gotten more prominent since then. A few times when I gave it some good throttle at lower speeds to pass a car or something it gave me loud engine knock sound before a slightly delayed downshift, didn't seem right.

Here is a recording of the noise, it is sporadic throught but easily heard at 1:22-1:27 into the video:

2. For the last week the car idles low, around 450-500 rpm. This has occurred since I had the air conditioning compressor replaced last week. It goes up to 800 when the compressor is on. Otherwise the idle is smooth and the car runs well.

I have now tried different sound equalizer settings, FULL volume, and even a different speaker set, and I still cannot discern anything that I recognize as a "ticking" sound, only the obvious change in tire noise during differing pavment composition sections.

But.

I note that at time 0.25 you reach over and switch off the climate control system, inclusive of the A/C compressor clutch.

Once you do that the previously stored liquid refrigerant will begin to bleed down since the metering into the evaporator does not close. I would be surprised if you could really discern the change in the noise level of the evaporator from that but I suppose anything is possible.

There are also a couple of things that will/might happen automatically as a result of switching the system off.

The climate control will evenually, maybe even right away, change, FORCE, the system's inlet airflow vane/door position from recirculate to FRESH. Be aware that in the previous "auto" mode unless you had specficially, manually, selected "FRESH" mode the inlet airflow might have been at any intermediate level, even in FULL recirculate mode. This, even with the "fresh" indicator brightly lighted.

The second thing the system might/will do, automatically, is switch the system airflow into strictly, FULL, windshield airflow, OUTFLOW, mode.

This latter function serves 2 purposes. With the system off the presumption is that you wish to minimize the level of airflow entering the cabin, more correctly stated the level if FRESH, possibly COLD airflow coming through the system due to forward motion of the vehicle. Forcing that incoming airflow to reverse flow direction will serve to reduce, "baffle", the volume of airflow.

The second is quite possibly of substantually greater importance. Having the incoming outside airflow routed to the windshield will most certainly help to alleviate the possibility of interior windshield fogging.

Having EITHER servomotor, the outside air inlet vane/door, or the windshield airflow routing, not be able to reach their respective "end-travel" fully open or closed as the case may be, will most definitely result in a series of "clicks", clicking, until the serrvomotor controlling ECU decides to give up.

This servomotor end travel "clicking" issue can be asserted by disconnecting the battery and then listening to noise from the dash area as the battery is reconnected. The climate control system will go through a sequence to recalibrate, relearn, the end-travel points, fully off and fully closed, of all system vanes/doors.

[Ancdmd]

I had the compressor replaced because it was not engaging periodically, especially when it was really hot outside. It would take about ten minutes for it to engage, and only hot air would blow until then, at which time it would immediately blow cold. The tech had seen it before and apparently something in the compressor was locking up and would take a bit of time to unsieze and then it would work fine. Replacing the high pressure switch had no effect, however leaving the refrigerant volume a little low would lessen its occurrence. I have gone through the climate control system and not found any relation to the noise issue I have. I am familiar with the common whistling sound of the expansion valve which is a separate issue.

The clinking noise doesn't sound like a tick, it sounds more like metal objects in a tin can rattling around, or kinda like a handful of small bells jingling. On my iPad when I play the video I cup my hand around the speaker to amplify the volume and direct it to my ear and I can easily hear it between 1:22-1:27. This video was recorded a couple months ago, and the sound is even louder now. I've become adept at feathering the gas pedal to provoke it. Regardless of any climate control settings the sound is always there, as if it was something bouncing around in the exhaust system or the transmission, or some kind of bracket somewhere that is loose.

[Ancdmd]

I will try turning off the climate control, disconnecting the battery for a little while and reconnecting it to see if that takes care of the idle issue.

[Ancdmd]

One more thing, this noise occurs only at a point where it seems the load of the drivetrain under throttle and the reverse load of the drivetrain when coasting is "balanced". In other words, if the engine is being given any throttle it will not make the noise, nor if the car is purely coasting. It only occurs at the transition point between those two opposing loads on the drivetrain.

[landar]

That latest description leads me to think more in terms of a universal joint in the drive shaft or CV joint in the rear axles. You might want to get underneath and "rattle" those parts checking for slop. Maybe even something amiss in the rear differential (fluid level, gear mesh?) Just speculation on my part, however. Take it with a grain(or two) of salt.

[jaswood]

"..especially hot outside..."

Possibly a VERY key statement.

If the engine coolant begins to rise to, near, the point wherein a overheat condition would result, the A/C compressor will be disabled PRE-EMPTIVELY so as to prevent an actual overheat condition. Now, without the "burden" of pre-heated airflow from the A/C condensor reaching the radiator the coolant temperature will most likely decline back down the point wherein the A/C will again become operational.

IMMHO the above condition most often results in failured or failing radiator eelctric cooling fans. Some do not operate at all unless the A/C active and/or the engine coolant is already approaching ~180F. Some with two fans will run them in series, only 6 volts each, unless/until the A/C is active or the coolant is tending toward overheating in which cases they are switch to parallel operation, a full 12 volts each.

This latter case, both fans running, often fools auto mechanics/technicians into thinking all is well with the cooling fan operation when it is NOT. The 12 volt parallel operation is OFTEN required and if the fans do not properly switch into that mode to provide the extra necessary cooling the symptom you describe will result.

"..leaving the refrigerant volume low..."

Yes, EXACTLY, not enough LIQUID refrigerant available for full time coolling, only ~70% of the needed compressor cycling, the A/C condensing will not provide a HIGH heat load to the downstream radiator....

A bit counter-intuitive, but if you turn your temperature setpoint to MAXIMUM cooling and the use the blower speed to manually control the cabin comfort level this problem will abate. In maximum cooling mode the system's reheat/remix path will be closed to REHEAT thereby dramatically increasing the effectiveness, efficiency, of the A/C and the compressor cycling, the need to COOL the A/C condensor, might be reduced by a 10:1 factor.

I have used this technique myself when one of the radiator cooling fans failed in my '01 911/996 C4 and the engine temperature began to climb into the RED. Mid-August, HOT day, dead-slow traffic on I40 around Little Rock Ar...

[jaswood]

I had the compressor replaced because it was not engaging periodically, especially when it was really hot outside. It would take about ten minutes for it to engage, and only hot air would blow until then, at which time it would immediately blow cold. The tech had seen it before and apparently something in the compressor was locking up and would take a bit of time to unsieze and then it would work fine. Replacing the high pressure switch had no effect, however leaving the refrigerant volume a little low would lessen its occurrence. I have gone through the climate control system and not found any relation to the noise issue I have. I am familiar with the common whistling sound of the expansion valve which is a separate issue.

The clinking noise doesn't sound like a tick, it sounds more like metal objects in a tin can rattling around, or kinda like a handful of small bells jingling. On my iPad when I play the video I cup my hand around the speaker to amplify the volume and direct it to my ear and I can easily hear it between 1:22-1:27. This video was recorded a couple months ago, and the sound is even louder now. I've become adept at feathering the gas pedal to provoke it. Regardless of any climate control settings the sound is always there, as if it was something bouncing around in the exhaust system or the transmission, or some kind of bracket somewhere that is loose.

"..feathering the gas pedal to provoke..."

Broken honeycomb structure within a catalytic converter....?

I have experienced the catalyst film coated honeycomb structure within the converter failing, crumbling apart in chunks. But that almost always at first resulted in those chunks blocking the exhaust flow intermittently, sometimes causing the engine power level to be reduced for acceleration.

Idle exhaust flow pressure wouldn't rattle them about, and POWER level exhaust pressure would force them against the rear section of the converter..but engine feathered...

More than maybe.

[jaswood]

One more thing, this noise occurs only at a point where it seems the load of the drivetrain under throttle and the reverse load of the drivetrain when coasting is "balanced". In other words, if the engine is being given any throttle it will not make the noise, nor if the car is purely coasting. It only occurs at the transition point between those two opposing loads on the drivetrain.

I understood, understand, FULLY, what engine "feathering" means....

But thanks for the clarification anyway.

[Ancdmd]

This a/c problem was occurring for about two years. It would happen mostly during the warmer months here in S FL, and also usually when the engine was COLD. Every time in the morning on my way to work, I would have to drive for about ten minutes waiting for cold air to blow. The problem was a lot less likely to occur if the engine was already hot, but what was frustrating was that it was still hard to predict when it would happen. One thing was for sure, if I had a girl with me on a hot summer night or if I was dressed nice and didn't want to sweat it would SURELY happen and really *BLEEP* me off!

I do have a very slow refrigerant leak in the evaporator which requires topping up yearly with about .75 lbs. During the past Fall the compressor was functioning fairly well, and then a few months ago after topping it up the compressor was really reluctant to engage for the entire weekend after. I went back to the shop and the tech removed some refrigerant and it now engaged almost always. I could tell the level was low by the whistling noise from the expansion valve. For the last month or so I did notice the air blowing a little warmer while sitting at a red light sometimes, and during the recent compressor swap the tech noticed both cooling fans only working intermittently, one more than the other, so I just replaced both.

If my a/c problem wasn't the compressor, then what was faulty? Am I missing something?

the tech took a rubber mallet to to rear cat and didn't hear anything. He wanted me to leave the car for a day so he could spend more time with it.

[Ancdmd]

I had thought about that cat, but now I'm more inclined to think its the driveline. I don't get any vibration or shutter at any speeds or rpm's. The noise sounds like its coming from the front half of the car and not the rear.

[jaswood]

I had thought about that cat, but now I'm more inclined to think its the driveline. I don't get any vibration or shutter at any speeds or rpm's. The noise sounds like its coming from the front half of the car and not the rear.

When the rear diff'l MAIN cushion/mount had failed I was absolutely certain the noise I was hearing was just underneath my feet.

But the way you described the sound "rock in a tin can" makes me think you have a chunk of catalyst structure, while not (yet) large enough to block exhaust flow, rattling around within the converter.

Also, that would put the origin of the sound right at your feet.

Have you checked for a loose r CRACKED converter heat shield?

Harmonic vibrations are a strange thing, a loose heat shield might very well vibrate only at certain engine RPM and driveline "stress" points. Wouldn't be the first time.

You s

[stevenf]

I think I have the exact same "tinkering when feathering throttle" problem, the noise sounds like coming from engine bay, not from rear end or underneath.

It happens every time when throttle is at the blink of opening and closing, not only when feathering the paddle, it also happens when cruise control is transiting between acceleration to coasting.

Ancdmd, have you found out what's the problem in the end?

[90Duchess]

I, too, am intersted in knowing if the OP found out what was causing that metallic noise. Personally, based on the description, I thought it sounded more like a dry/failing drive shaft carrier bearing...

[stevenf]

He found the root cause is the "Driveshaft adjusting nut" on the front half of the driveshaft got lose.

See detail and picture here:

http://www.clublexus.com/forums/ls430/770272-what-would-happen-if-this-nut-loosened-2.html#post8911244

[90Duchess]

awesome! I found that same nut loose on my ls400 after a shop repair and tightened it up myself, fortunately before any noise or problems arose. Thank goodness you got it fixed before it caused any major problems! arent't our collective minds on this forum awesome?? I hope your car gives you many more trouble-free years to come!

[landar]

Steven, thanks much for posting that link!

Many 'play' both forums and forget to post the solution back to one of them. This will keep things in sync as to this particular problem.