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When changes from 4th to 3rd (or 3rd to 4th) is very smoothly.
I perceive only watching RPM.
For example, if I run
constantly in 4th @ 44 MPH engine rotate ~1300 RPM
constantly in in 3rd @ 40 MPH, engine rotate ~1650 RPM
Originally Posted by CathedralCub
Okay, but here'* the thing: I gave you such a specific list of steps for a reason
1. Dead stop in "Park" <<<Now we know exactly what your configuration is as you are starting 2. Manually select "1" <<<Now we know you have selected 1st gear 3. Accelerate gradually until the engine is at 2,500RPM <<<Now we know you are doing 2,500RPM in the gear you are in, that might be the gear you selected or might not 4. Hold this speed for five seconds <<<Now we know you are stabilized at 2,500RPM in this gear 5. Manually select "2" <<<Now we know you have selected 2nd gear 6. What is the RPM now? <<<Now we know the difference that this gear change made, and can do a little math to figure out what gear it ended up in 7. Hold this speed for five seconds <<<Now we can tell if the torque converter clutch may have engaged or not, helping our math 8. What is the RPM now? <<<Now we can tell if the torque converter clutch may have engaged or not, helping our math 9. Accelerate gradually until the engine is at 2,500RPM <<<Now we know you are doing 2,500RPM in the gear you are in, that might be the gear you selected or might not 10. Hold this speed for five seconds <<<Now we know you are stabilized at 2,500RPM in this gear 11. Manually select "3" <<<Now we know you have selected 3rd gear 12. What is the RPM now? <<<Now we know the difference that this gear change made, and can do a little math to figure out what gear it ended up in 13. Hold this speed for five seconds <<<Now we can tell if the torque converter clutch may have engaged or not, helping our math 14. What is the RPM now? <<<Now we can tell if the torque converter clutch may have engaged or not, helping our math 15. Accelerate gradually until the engine is at 2,500RPM <<<Now we know you are doing 2,500RPM in the gear you are in, that might be the gear you selected or might not 16. Hold this speed for five seconds <<<Now we know you are stabilized at 2,500RPM in this gear 17. Manually select "4" <<<Now we know you have selected 4th gear 18. What is the RPM now? <<<Now we know the difference that this gear change made, and can do a little math to figure out what gear it ended up in 19. Hold this speed for five seconds <<<Now we can tell if the torque converter clutch may have engaged or not, helping our math 20. What is the RPM now? <<<Now we can tell if the torque converter clutch may have engaged or not, helping our math 21. Procedure complete <<<Now we can do some math to help figure out what'* going on
Maybe it really is shifting 1, 2, 4 . Maybe it is really shifting 1, 3, 4 . Maybe it is really shifting 1, 2, 3, then engaging the converter clutch. Maybe several other things. Doing this procedure will get us closer to helping you solve this issue.
but he wanted an answer that is yes/no and requires no input on his part
From “P” changed lever in “1”
Reached 2500 RPM in 1st gear for 5s: speed is 19 MPH
changed lever to “2”
now is 1650 RPM at speed 19 MPH
after 5s at same speed: 1500 RPM
Reached 2500 RPM in 2nd gear for 5s: speed is 36 MPH
changed lever to “3” (and gear didn't change)
now is 2500 RPM at speed 36 MPH
after 5s at same speed: 2500 RPM
Reached 3000 RPM in 2nd gear for 5s: speed is 43 MPH (and gear didn't change yet)
changed lever to “D”
now is 1300 RPM at speed 43 MPH
after 5s at same speed: 1250 RPM
If your PCM is commanding 3rd gear and the TCM is doing it'* job then it'* an internal problem. You are going to need it torn down. I have the 4T60E manual from ATSG. Here'* where you could be having a problem.
From “P” changed lever in “1”
Reached 2500 RPM in 1st gear for 5s: speed is 19 MPH
changed lever to “2”
now is 1650 RPM at speed 19 MPH
after 5s at same speed: 1500 RPM
Reached 2500 RPM in 2nd gear for 5s: speed is 36 MPH
changed lever to “3” (and gear didn't change)
now is 2500 RPM at speed 36 MPH
after 5s at same speed: 2500 RPM
Reached 3000 RPM in 2nd gear for 5s: speed is 43 MPH (and gear didn't change yet)
changed lever to “D”
now is 1300 RPM at speed 43 MPH
after 5s at same speed: 1250 RPM
Yeah, definitely skipping 1:1 3rd gear. I agree the transaxle will need to be overhauled.
The only thing I can think of is to check functionality of the shift solenoids, and also remove them and make sure the passages are clear, but even if that does fix it I'd bet the transmission has bigger issues.
Last edited by CathedralCub; Sep 11, 2022 at 01:50 AM.
Reason: Added the last sentence
