Mysterious issues: Is it transmission shudder or something else?

[LX470MMMM]

A few weeks ago my LX470 (2000) suddenly had the typical transmission shudder. Starting at around 45 mph (sometimes more, sometimess less) there is shuddering under light acceleration. If I stepped on the gas more and it switched to 3rd it would accelerate fine. On top of that there was suddenly an intermittent short shudder at idle when in drive (like stopping at traffic lights for example as a classic situation). No CEL has come on.

To fix this we flushed the transmission fluid and lubed the ujoints. Right after that the shudder was still there but much less pronounced. It was barely noticeable. After about 300 or so miles the shudder got stronger again, but not to the extend of the situation before the transmission fluid flush. Still annoying however. My mechanic suggested adding Lubeguard Antishudder. The first tube didn't seem to do anything so I added another tube which seems to be recommended due to the large amount of transmission fluid it has to mix with. I am not sure yet if the shudder is still there. I tried it out and couldn't reproduce it anymore but it would probably require another few hundred miles of driving to see if it is really gone. When the transmission fluid was flushed the old fluid looked quite good still with no debris or any concerning color, smell etc.

To avoid the shudder I have got into the habbit of accelerating a bit harder to make the transmission go to 3rd gear. I noticed that now at around 2000 RPM there is a slight hesitation seemingly coming from the engine. It does not accelerate smoothly until it hits about 2500 RPM. This issue of fluctuating engine power at around 2000 RPM was already there 8 months ago but then disappeared. Back then there were CELs on for lean fuel mixture and misfire + coil. I put in a new fuel pump and replaced one ignition coil which fixed the issue. The confusing thing is that now there is no CEL.

What should I do about this? Change all coils as maintenance? Fuel filter was never changed AFAIK. Maybe this should be done? I was also thinking about the PCV valve and replacing it. Last time I changed engine oil the oil had quite a strong fuel smell which seemed odd as I do long distance trips regularly. I also had several vacuum leaks that got fixed 8-9 months ago when the CEL came on.

 

[Dirt J]

Did you replace with an OE fuel pump?

 

[2001LC]

I do full 12 qt. flush in the 98-2002 AT, with mobile 1 MV ATF. To often drain & fills are done with different brands fluid mixing fluids. Not a good idea to mix.

Some I've found AT wire harness damage, resulting in strange issue. One way to help diagnose if mechanical or electrical. Manually shift through the gears. If issue goes away. It is then likely electrical.

Very often these "shutters" are not AT, but a misfire. Most time misfire is spark related. Mostly weak/bad coils (COP). These misfires, can be seen in Tech Stream.



Some misfires are bad spark plugs, but they tend to result in a CEL with P03**.

Thread 'Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert!'

Mar 3, 2018

TICK TICK TICK POP POP POP is a ticking time bomb, often mistaken as exhaust manifold crack or gasket leak leak.

ALERT, ALERT, ALERT: Spark plugs are working themselves loose. "Walking Out" Then blowing out of head, taking their female threads of head with them! Very damaging!

You think TICK or POP, is blown exhaust gasket or crack exhaust manifold. Replace the spark plugs. If tick doesn't go away, then you've confirm exhaust leak. Exhaust leaks anywhere need to be taken care of. But they're less damaging if damaging at all. But, if you blow...

• 2001LC
• Replies: 572
• Forum: 100-Series Cruisers

• 
• 

They can be fuel injector. But those also tend to set off CEL.

Thread 'When to Clean or Replace fuel injectors'

Jan 14, 2016

Please post your experiences and thoughts on the subject.

I’ve been considering cleaning or even replacing all 8 fuel injectors, is this wasting time and money. I understand keeping fuel injector clean by adding a can of additive to the gas tank, now & then, is a good practice. This keeps them operating at peak performance, but for how long. When should we do more and what should be done. Do they weaken over time reducing performance or preform at peak until failure. I’ve read they’re good for 1 billion cycles, which I've read is ~350K miles. How about seals, should they be included...

• 2001LC
• Replies: 43
• Forum: 100-Series Cruisers

• 

Been looking at AT lately. Mostly focused on valve body, solenoids and solenoid wires.

Thread 'Alert, Alert, Alert----- Transmission valve body wire housing block! --- Have you looked into yours? Capillary action drawing ATF in!'

Nov 23, 2025

This automatics transmission's (A/T), wire housing block on driver side (LH) of A/T. Which connects to solenoids & temp sensor(s) within A/T case on valve body. Is heavily coated inside with a gray/green GOO. What is this GOO?

Any guesses what thick appearing oil substance is?

Anyone have pictures or can comment on theirs, they care to share here?

Edited 12/14/25:

As you read through this thread. It will become apparent we've ATF capillary actuation issues with: Transmission wire, that come out of A/T case from inside transmission. It's the wire housing, that connects all valve body...

• 2001LC
• Replies: 62
• Forum: 100-Series Cruisers