Stock 4L65E sluggish 1-2 shift at light throttle - Dashboard attached

[pacer265]

Hi,

I'm in the process of diagnosing a problem with my transmission and was hoping someone could confirm my reading of the logs.

The transmission is a 4L65E behind a LS1 and has done about 70000km since new. It still has the original transmission fluid which looks to be in good condition (not burnt) and at the correct level. A factory oil cooler is fitted as standard.

The tune is using the factory calibration.

The problem is a slugglish 1-2 shift taking its time that only appears when:

- After driving in the medium to heavy stop/start traffic
- At very light throttle opening
- On an incline/hill

The shift commences, not much happens for a while then it finally engages properly.

I've attached a dashboard which shows various PID's during the shift.

My observations of the PID's are:

- the measured time of the shift is about 0.6s as shown by the elasped time
- the SHIFT12 PID also displays 0.6 as the time taken
- the programmed shift time is 0.45s which gives a SHIFT12ERR of about 0.15s
- prior to the shift, the ADAPTSHIFT drops slightly for a smoother shift (-0.75)
- but when the shift doesn't complete after 0.533s, ADAPTSHIFT then increases to raise the line pressure to aid completion of the shift (0.5)

What I'm thinking at the moment is:

- this has started only in the last 2000km so it is probably mechanically related
- it only occurs when at light throttle up a hill when the TFT is hot
- change the transmission oil and hope this cures the problem
- otherwise this is likely to get worse over time and further problems are likely to appear

Any flaws with the above diagnosis/observations?

Cheers