A343 trans 1-2 shifting slowly/mushy (1 Viewer)

[ktknaack]

just did this

I just went through similar problems with my 93 US Spec. 80. I have the 442 but similar issues. I have found that my trans. is very picky about the fluid. I have changed it about every 20K miles and found much improvement in overall performance. I had sloppy shifting in stop and go traffic. 1st to 2nd in either direction was slow at best unless very specifically stoping or starting. Didn't like to be right between where either gear could have done. I am on 33" tires with a small lift but I would some time use the ect button to help it hold 1st gear a little longer. Ultimetly I started to loose first gear some times. It was there if you put it in 1st gear but otherwise you could put it in neutral then back and drive and normaly get it back. I called wholesale automatic trans. in Australia and they told me they thought solinoids were going... also why ambient temp and temp of truck made it act different.... They let me know that Slee off Road had the upgraded valve body assemly and it had 4 new solinoids on it. I figured if I had to drop the pan I would be a fool to not replace all of them. Where one fails the others couldn't be that far behind. For about 800 the trans. is better than new. Overall better shift points and speeds. Clean, crisp... it made a big difference and fixed the problem. Best money I have spent to date. If you plan to keep the truck its worth it.

 

[powderpig]

I know in the 94 FSM their is a test for the solieniod before you have to tear it out. On the 95-97 trucks the tranny computer is in with the engine computer, so the test may be different. I do not have a 95-97 FSM currently. If you do,have a FSM you may find a test you can preform with a VOM to see if the coil is with in specs, thus good. later robbie

 

[Smaddox]

Opening up a dead thread. Struggling to find an answer to my problem. Here goes.. 01/95 K292/A343F 1FZ-FE

Did a HG replacement. Only replaced gaskets for the most part. Prior to HG replacement the transmission was shifting ok'ish. 1st was fine, maybe a little low in the RPMs on shift because 2nd was always a slog. But it was never a hard shift. Just lacked power until you hit around 2000 RPMs in 2nd. After rebuild, it's shifting really soon in all gears. Which is making it feel almost like the engine is in limp mode. No codes (dash lights are not working, but obd2 codes are clear). The 2nd/ect switch does not seem to be working (prior to rebuild the pwr light never shown on the dash, but 2nd did?). If I put the transmission into 2nd, the vehicle will rev up to about 2.25k RPMs in 1st, then shift into 2nd, the RPMs will go as high as I'm willing to get them. (this is why I'm eliminating fuel pressure and timing) Also, when trying to address this from a potential vacuum issue or fuel pressure issue I did get 2 test drives where it was running as normal. Maybe higher than it should shift points. It was not consecutive, and the next day it was doing the same low shift points.

Is this likely the transmission thats the issue? If so, anyone have any ideas where to start on the diagnosis?

Thanks in advance!

 

[shocktower]

Opening up a dead thread. Struggling to find an answer to my problem. Here goes.. 01/95 K292/A343F 1FZ-FE

Did a HG replacement. Only replaced gaskets for the most part. Prior to HG replacement the transmission was shifting ok'ish. 1st was fine, maybe a little low in the RPMs on shift because 2nd was always a slog. But it was never a hard shift. Just lacked power until you hit around 2000 RPMs in 2nd. After rebuild, it's shifting really soon in all gears. Which is making it feel almost like the engine is in limp mode. No codes (dash lights are not working, but obd2 codes are clear). The 2nd/ect switch does not seem to be working (prior to rebuild the pwr light never shown on the dash, but 2nd did?). If I put the transmission into 2nd, the vehicle will rev up to about 2.25k RPMs in 1st, then shift into 2nd, the RPMs will go as high as I'm willing to get them. (this is why I'm eliminating fuel pressure and timing) Also, when trying to address this from a potential vacuum issue or fuel pressure issue I did get 2 test drives where it was running as normal. Maybe higher than it should shift points. It was not consecutive, and the next day it was doing the same low shift points.

Is this likely the transmission thats the issue? If so, anyone have any ideas where to start on the diagnosis?

Thanks in advance!

In limp mode, it does just that limps, there is a newer thread on updating the throttle body, search for it, also fix all of you lights so you can see what's going on. When is the last time you did a full service change on your tranny filter fluid ?

 

[Smaddox]

Should have been done about 2k miles ago. That's when I bought it and had a full service done. Can't say for sure on the filter. HG blew after that. Hose went out and it over heated. No lock up, but coolant was burning. I'll get into the lights today. Whomever owned it before did a lot of funky stuff with the wiring.