Transmission downshift issue - 2001 LX470 (A343F) (1 Viewer)

[LX471]

I’m having an issue with my transmission. When I’m slowing down to a stop or to a very slow speed from 20 mph+, my transmission has an issue downshifting and it feels like the transmission is in neutral when I try to accelerate. Eventually, it will kick into gear (the higher I'm revving, the harder it slams into gear) but sometimes it takes 2-3 seconds and it's just in neutral until it does.

Other than this problem the transmission works perfectly.

The fluid looks clean and the fluid level reads correctly on the dipstick both, hot and cold. The lx has 200k, but it’s pretty new to me and I’m not sure of the history. It isn’t throwing any codes. Some of the threads I’ve read may point to shift solenoids, but wouldn’t there be check engine codes if the solenoids were failing (that’s what the transmission shop thought).

I’ve taken it to a couple of shops including a transmission shop. The transmission shop recommended replacing the transmission to fix the problem. None of the mechanics have really had any solid ideas as to what could be causing the issue.

Obviously, if there is a way to fix the problem without replacing the transmission that would be ideal, so just want to exhaust all options before opting for a replacement.

Thanks in advance for any help!

 

[SteveH]

The FSM may gave a procedure to check some basic pressures that have to be in the right range for the trans. to shift properly. 99/100 shops will just tell you to replace the transmission due to miles or laziness on their part. Many shops won't touch Japanese stuff or have zero experience, since all they work on are Ford/Chevy/Dodge.

Since it's inexpensive, if you haven't, you should pull the trans. pan, inspect the filter, and study the valve body for loose or missing bolts (that will be in the pan). If the filter were plugged, you could have low pressure causing this. At least if you end up replacing the trans, you can feel better that you did some due diligence on your current transmission before pulling the expensive trigger.

 

[2001LC]

A few things I'd try:

1. Mark sure engine is well tuned. This includes no vacuum leaks. All wires & wire housing blocks on engine & transmission in good working order
2. Make sure: Engine Coolant Temp (ECT) in range of 184-187F (1998-2002). ECT Must be read through tech stream, dash gauge is useless. Many Tech stream blue-tooth plug-in dongles, that display on smart phone on the market. That will give both: ECT & A/T fluid temp,. They also read codes and much more data..
3. Do a full 12 quart A/F flush with Mobil 1 MV ATF. Set level with A/T fluid temp about 160F (FSM rec. 158f-176f) This is key!

Every transmission that has come to me, that some shop said replace. They'd all had a drain and fill (~4qt with who knowns with what A/T fluid). In each, I did above 3 steps. After the full 12 qt flush, all good as new!

 

[FSAuto]

A few things I'd try:

1. Mark sure engine is well tuned. This includes no vacuum leaks. All wires & wire housing blocks on engine & transmission in good working order
2. Make sure: Engine Coolant Temp (ECT) in range of 184-187F (1998-2002). ECT Must be read through tech stream, dash gauge is useless. Many Tech stream blue-tooth plug-in dongles, that display on smart phone on the market. That will give both: ECT & A/T fluid temp,. They also read codes and much more data..
3. Do a full 12 quart A/F flush with Mobil 1 MV ATF. Set level with A/T fluid temp about 160F (FSM rec. 158f-176f) This is key!

Every transmission that has come to me, that some shop said replace. They'd all had a drain and fill (~4qt with who knowns with what A/T fluid). In each, I did above 3 steps. After the full 12 qt flush, all good as new!

Don't mean to thread hijack but I'm facing what I see as a similar issue to OP. P to D & R to D rarely, but sometimes, will take a while to engage as well as a concerning thud that occurs after getting back on the gas when coasting. I've done all the usual driveline inspection/lubrication each oil change and I'm still having the issue. Same as OP, no other notable transmission issues.

My question: I'm at 263k (2006 LC) with unknown Transmission service history, is it worth doing a fluid flush w/ a pan drop or will I potentially be in for more issues?

 

[Mike NXP]

Don't mean to thread hijack but I'm facing what I see as a similar issue to OP. P to D & R to D rarely, but sometimes, will take a while to engage as well as a concerning thud that occurs after getting back on the gas when coasting. I've done all the usual driveline inspection/lubrication each oil change and I'm still having the issue. Same as OP, no other notable transmission issues.

My question: I'm at 263k (2006 LC) with unknown Transmission service history, is it worth doing a fluid flush w/ a pan drop or will I potentially be in for more issues?

Above advice given by 2001lc is the best place to start.

 

[2001LC]

Don't mean to thread hijack but I'm facing what I see as a similar issue to OP. P to D & R to D rarely, but sometimes, will take a while to engage as well as a concerning thud that occurs after getting back on the gas when coasting. I've done all the usual driveline inspection/lubrication each oil change and I'm still having the issue. Same as OP, no other notable transmission issues.

My question: I'm at 263k (2006 LC) with unknown Transmission service history, is it worth doing a fluid flush w/ a pan drop or will I potentially be in for more issues?

If it fails after full 12 qt flush. It was bad to begin with.

I made no mention of a pan drop. Although a pan drop may reveal excessive metal on pan magnets.

I did mention A/T fluid temp. But I failed to mention: It's a good idea to start with monitoring A/T fluid temp along with ECT and fuel trims as start to diagnosing.

What I've outline is to make sure, someone hasn't caused what appears to be a bad transmission in 98-02. Which has been the case, in everyone that has come to me with transmission issue. This is not to say a transmission can't go bad. But other than some very early 2000, going bad. I don't see them! Even those, I didn't see, only heard about.

@FSAuto. I'd first check your FDS outer axle, hub flange & snap ring. In addition to what I outlined above. Understand also: 04-07 Transmission, factory underfilled them. We need set level to a lower A/T temp of 97-115F.

So often, someone does the recommended drain & fill. They drain out perhaps ~3 qts and added back ~3qts. Never checking level or they use the flashing dash light to set level. Those transmission levels are likely set wrong. To low in most cases. They also will very often use some cheap off-the-shelve bulk ATF. Which mixing fluids, can also cause problems. A transmission run to low or with contaminated fluid to long, may be damaged, but I've yet to see one that was.

I have done a few drain & fills, to easy transmission to a better fluid condition, in past. These days, I just jump right in with full 12qtl flush.

Many fear a full 12 qts flush. But fact is, if a transmission fails after a proper full 12 qt flush. It was a bad transmission before the flush. I'd rather find-out now while near home. Rather than 500 miles deep off-road.

BTW: I've done flushes in as high as 375K miles. Not one has failed. All that had issues, improved after.

 

[FSAuto]

If it fails after full 12 qt flush. It was bad to begin with.

I made no mention of a pan drop. Although a pan drop may reveal excessive metal on pan magnets.

I did mention A/T fluid temp. But I failed to mention: It's a good idea to start with monitoring A/T fluid temp along with ECT and fuel trims as start to diagnosing.

What I've outline is to make sure, someone hasn't caused what appears to be a bad transmission in 98-02. Which has been the case, in everyone that has come to me with transmission issue. This is not to say a transmission can't go bad. But other than some very early 2000, going bad. I don't see them! Even those, I didn't see, only heard about.

@FSAuto. I'd first check your FDS outer axle, hub flange & snap ring. In addition to what I outlined above. Understand also: 04-07 Transmission, factory underfilled them. We need set level to a lower A/T temp of 97-115F.

So often, someone does the recommended drain & fill. They drain out perhaps ~3 qts and added back ~3qts. Never checking level or they use the flashing dash light to set level. Those transmission levels are likely set wrong. To low in most cases. They also will very often use some cheap off-the-shelve bulk ATF. Which mixing fluids, can also cause problems. A transmission run to low or with contaminated fluid to long, may be damaged, but I've yet to see one that was.

I have done a few drain & fills, to easy transmission to a better fluid condition, in past. These days, I just jump right in with full 12qtl flush.

Many fear a full 12 qts flush. But fact is, if a transmission fails after a proper full 12 qt flush. It was a bad transmission before the flush. I'd rather find-out now while near home. Rather than 500 miles deep off-road.

BTW: I've done flushes in as high as 375K miles. Not one has failed. All that had issues, improved after.

That definitely makes me feel a bit more confident about doing a full flush, which was my plan.

Currently, as I’m typing, replacing my CVs with new OEM units, hub flanges, and snap rings as well as repacking and presetting bearing break away (all thanks to your videos!).

I did order 12qts of WS ATF so I’ll plan a flush as my next project.

Thanks for the input.

 

[Eicca]

Make sure ground point EC, located on the back of the passenger side cylinder bank (you can’t see it as it faces the firewall), is secure.

That ground came loose on my parents’ 1999 and caused all kinds of havoc. Tightened it down and it’s been fine for years since.

 

[LX471]

Solved
It's been a little while since I posted this last summer, and I forgot to reply after solving the problem. Thank you to everyone that provided advice!!!
A quick review of the problem: The transmission would nuetralize when slowing down and/or stopping, leaving the vehicle unable to move forward. After 1-2 it would clunk back into gear. Additionally, after the vehicle warmed up, if I checked the dipstick, the tranmission fluid would spew out of the dipstick tube. I was constantly adjusting the fluid level, and could never get a good reading on the fluid level.

I did a full transmission flush with Mobil 1 ATF, but the problem still persisted.

After a couple mechanics couldn't figure it out, the spewing of the fluid made me think it could be an issue with the venting of the transmission (after several months and countless hours thinking about it). So I got a flashlight and found the vent/breather hose connectingthe top/front of the transmission to the upper part of the dipstick tube was kinked! I replaced this hose, and problem solved! (attached is a photo of the tube

I'm attaching a photo of the kinked tube, and also a diagram with the tube circled.

Hope this helps someone!

 

[2001LC]

Interesting, a kink in breather hose, caused so much of an issue.

In 98-02. The A/T and Transfer Case breather are Y together, near back of A/T. With just the one long (kick) hose to a single breather at dip stick. We're finding the long breather hose clogged, restricting air flow. This can result in exchange or fluid between TC & A/T. Be a very good idea, to flush the TC also.