: Transmission: manual shift operation



n7don_srx
04-01-07, 05:35 PM
If I manually downshift from M5 to M4 and back to M5 the transmission doesn't appear to upshift back to M5. As an example at 70 mph, engine rpm will increase a few hundred rpm when I shift to M4 but if I manually upshift to M5 and hold a steady speed the transmission doesn't appear to upshift back to M5. I'm basing this on the fact engine rpm stays at the M4 rpm level. If I accelerate to something above 70 the transmission does upshift but only if I have accelerated. I did a cursory forum search but didn't see any similar inquiry. Is this normal operation? Anyone else experience this? All other aspects of shift points, shift quality, etc. appear normal.

deville555
04-02-07, 12:03 AM
When you shift do you do it electronically? It probably is just a request and the PCM doesn’t allow the upshift until its criteria is met first which happens to be around 70mph.

n7don_srx
04-02-07, 12:30 AM
Yes, shifting electronically.. it's strange as long as I don't accelerate to a point of upshift it will stay in M4 indefinately. Actually I need to go through the sequence at a lower speed to see when upshift occurs or if it's speed related. I know closed throttle or downhill makes no difference.

keeton
04-03-07, 02:12 PM
Do the '07s have an indicator showing what gear you are in when you are in manual mode? On my '04, the odometer becomes the gear indicator when in manual mode. If so, does the indicator say that you have upshifted to 5th?

Another thing that could be happening is that if you are under power, the torque converter will be slipping (on purpose) and the RPMs will only be loosely based on vehicle speed. Once the torque converter locks, RPM and vehicle speed will be in a constant ratio.

john d
04-03-07, 04:04 PM
Many months ago a contributor posted an article that was very detailed on how our tranny's behave. I recall that under some conditions a lower gear will hold even after removing power in anticipation of another surge of acceleration. Like when a driver downshifts a manual tranny going into a curve then powering out of the curve holding in the lower gear with a shift to higher gear when up to speed. That could be what's happening and is normal for this hi-tech tranny.

n7don_srx
04-03-07, 11:38 PM
Do the '07s have an indicator showing what gear you are in when you are in manual mode? On my '04, the odometer becomes the gear indicator when in manual mode. If so, does the indicator say that you have upshifted to 5th?

Another thing that could be happening is that if you are under power, the torque converter will be slipping (on purpose) and the RPMs will only be loosely based on vehicle speed. Once the torque converter locks, RPM and vehicle speed will be in a constant ratio.

When you go from auto to manual (which is called "sport" mode) an "S" appears next to the gear position indicator. Downshift will show "M4">"M3" etc, upshift "M5" etc. Move the shift level back to auto and the "S" goes away..... but the rpm stays at the M4 level.
Info in the Owners Manual does give some details that indicated sport mode will shift differently but not enough is given to know if the operation I descibed is normal. I suspect it is but wonder if anyone else has experienced the "no upshift" at steady speed, light load operation.
It isn't the torque converter lock/unlock