RPMs go up during shifting- Transmission Question

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ST8ROCKS

ST8ROCKS

Kevin
10 Year
Joined
Dec 28, 2010
Threads
108
Messages
588
Location
Beaufort NC
I have a 92 with 210K. The problem is that was the truck shifts from 2nd to 3rd the rpms will jump 100 or 200 before it goes into gear. If I am on the accelerator harder it will not be as noticeable. It also only does it between 2nd and 3rd. Checked the trans fuild its all good. It does not seem to have any other problems.

Thanks for the help!
 
Ok so this does pertain to the shift linkages. Thanks for the help, just wanted to make sure I didnt need to start saving for a tranny.
 
No the cable he is talking about runs from the TB to the transmission. If I understand it correctly it has something to do with increasing transmission shift pressure as throttle is increased. My cable is stretched so it is not adjusted exactly per the link that was provided. You may have to play with it a little to get the shifts how you like them. Too tight it will shift hard. Too loose and you will experience what you have described.
 
ST8ROCKS said:
Ok so this does pertain to the shift linkages. Thanks for the help, just wanted to make sure I didnt need to start saving for a tranny.
Click to expand...

You're fine; it's a common glitch on the 91-92's. Just tighten that cable till it feels right. It's ok to go by "feel" on this and re-adjust it a couple of times.

Your shift points will also move to higher RPM's (i.e., tranny will hold lower gears longer), which is usually a good thing.

Curtis
 
Hi, I had the same issue, but mine is a Diesel, so I am not sure for your LC. On the diesel pump there is a TPS (Throttle Positoin Sensor), that tells the car when to switch gears etc... I took mine off, it was quite stiff. I replaced it, and my LC switch gears like new.. No hunting, etc....

Maybe this helps...
 
Mine is doing the exact thing, 2nd to 3rd the RPM rises 300-400 RPM during moderate acceleration. I'll check this cable tonight! However, mine also looks like its leaking fuild (the bottom of the tranny and some of the t-case is oily and dirty.

1991 FJ80 with 229,000 miles.
 
I have a '94 Series HDJ80R-GNPEXW (auto) with a 1HZ engine conversion. I have the same issue between second and third where the revs climb noticeably higher and there is a delay to engage third gear. This also happens when kick down happens from third to second gear. All the other gear changes run smooth.

I am a bit sceptical about adjusting the throttle cable or has there been success with that? If so how come the other gear changes are good?

Thanks!
 
I assume you have an A442F?

You can try to check the solenoid valves as per the service manual. If you can't find one for the diesel, use one for the US spec gas models; the transmission is the same. The solenoid replacement requires removing the drain pan, but other than that, it's a pretty simple job. Messy, but simple.

Your description of the problem sounds to me like your clutches are slipping.
» If the engine rpm increases while shifting or under load, but below 55mph (or whatever that is in kph), it's the transmission that's at fault. If the engine rpm increases at between 50-55mph under slight acceleration, it's the torque converter, so watch the speed when you perform this test.

» If the engine rpms increase when shifting gears, but not under load, it's the clutch pack piston. The piston is leaking (there are two O-rings on it) until enough fluid gets into that circuit to create the required pressure to force a shift. If this condition persists, the clutches will eventually wear out too. The only fix is to replace the O-rings, which requires a teardown.
 
slabman3000 said:
I am a bit sceptical about adjusting the throttle cable or has there been success with that? If so how come the other gear changes are good?

Thanks!
Click to expand...
It's a completely free, easy to do adjustment that you can return to it's original setting if you change your mind, and it has cured the 2nd/3rd flare for many folks.

Why would you NOT try it?
 
CJF said:
It's a completely free, easy to do adjustment that you can return to it's original setting if you change your mind, and it has cured the 2nd/3rd flare for many folks.

Why would you NOT try it?
Click to expand...
CJF,
Thanks for the info, I have tried adjusting the throttle cable to various positions but no improvement. The next step is to explore possible TPS (Throttle Position Sensor) issue, pressure hose or even clutch slippage. Thanks to all for the advice so far, much appreciated!
 
Malleus said:
I assume you have an A442F?

You can try to check the solenoid valves as per the service manual. If you can't find one for the diesel, use one for the US spec gas models; the transmission is the same. The solenoid replacement requires removing the drain pan, but other than that, it's a pretty simple job. Messy, but simple.

Your description of the problem sounds to me like your clutches are slipping.
» If the engine rpm increases while shifting or under load, but below 55mph (or whatever that is in kph), it's the transmission that's at fault. If the engine rpm increases at between 50-55mph under slight acceleration, it's the torque converter, so watch the speed when you perform this test.

» If the engine rpms increase when shifting gears, but not under load, it's the clutch pack piston. The piston is leaking (there are two O-rings on it) until enough fluid gets into that circuit to create the required pressure to force a shift. If this condition persists, the clutches will eventually wear out too. The only fix is to replace the O-rings, which requires a teardown.
Click to expand...
Hi, yes A442F. Let me do the tests and report back.
 
Scalci said:
Hi, I had the same issue, but mine is a Diesel, so I am not sure for your LC. On the diesel pump there is a TPS (Throttle Positoin Sensor), that tells the car when to switch gears etc... I took mine off, it was quite stiff. I replaced it, and my LC switch gears like new.. No hunting, etc....

Maybe this helps...
Click to expand...
Hi, I did some inspection on my TPS and I found that the wires on the connector coming from the other end where the TPS connects to, is not in a good state and one of them even broken off. I disconnected the TPS and went for a drive and same shifting like always. So my question is what is the duty of the TPS then because disconnecting it causes no issue with shifting, Thanks

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slabman3000 said:
Hi, I did some inspection on my TPS and I found that the wires on the connector coming from the other end where the TPS connects to, is not in a good state and one of them even broken off. I disconnected the TPS and went for a drive and same shifting like always. So my question is what is the duty of the TPS then because disconnecting it causes no issue with shifting, Thanks
Click to expand...
Just to clarify, I think while inspecting I pulled on the wires and one of them must have broken off because of the state it's in. Took her out for a longer drive and for sure there is shifting issues and no down shifting until you stop. So that really answers my question about what the TPS does. Will get the plugg fixed then take it from there.
 
The throttle position sensor helps the TCU regulate the pressure within the valve body, which in turn effects the shift action. This is explained in the serivce manual. Defects in the circuit can cause delayed shofting, but it will not cause engine rpm to increase without a commensurate increase in wheel speed. That symptom is due solely to clutch slippage.
 
Hi All,
Just got my TPS plugg repaired. The electrician did point out something which I need advice on, maybe a part number if possible to replace. I have no connection shaft between the throttle cable and the kickdown cable (circles). My question is I've been running like this for who knows when but did not notice anything. Shifting is good in all gears except 2nd to 3rd where it flares, and kickdown also happens good when going uphill, so is this shaft between the two needed right?

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