Thread: Odd Shifting from start: 2-1-2-3-4 (4T65E-HD)

2000 Impala 3.8L 4T65E-HD

When slowing down to stop (red light, stop sign, etc.) I don't hear or feel any abnormalities. When I take off, the trans will begin in 2nd gear immediately kick into 1st gear (I feel a strong kick) and then shift normally to 2nd, 3rd, 4th, etc.

Please note that this problem happens more often when the transmission is warm (i.e. hot summer day or extensive driving).

I know this is a trans issue because if I manually shift it (1,2,3,4) the trans shifts fine. This has been going on for a couple years when I received the car. The fluid is clean. No check engine lights.

Anyone heard of something like this? Could this have anything to do with "OEM boost sleeve assembly wearing"?

Sounds like what mines been doing since i installed ZZP PCM.

There is a valve in the channel plate, the large casting under the valve body, and it is known on rare occasions to stick or the bore wears and can cause intermittent 2nd gear starts. It is called an AFL valve. I havent run across this yet but have read of a few other techs stumbling into this problem and it is a posted problem in one of my books. Unfortunately it means ripping half of your trans apart to get to and you may not even see a problem with it. Since it has been going on for so long I would suspect that or a valve body cross leak, bad gasket, pressure problem, etc. No quick easy answer to your problem but likely an involving fix.

Mine did this in winter time when it was really cold (believe it or not I paid attention to the occurrence and it had to be less than 40* for it to do so). If I started the car from after sitting all day like from having been at work, then took off, it was like you were taking off in second gear.

However, if I turned it on, let it warm up a few minutes, then turned it off and then back on, it seemed to be okay and would run perfectly. It had to be warmed up though, otherwise it was pointless.

However, when I tore the tranny apart I dont remember noticing any wearing or anything like that on the AFL valve, but I think there was one valve in the channel plate I have not been able to get out. I'll have to check that out today because that was on thing I was curious about when I started the tear down.

While in manual or tapshift mode it will likely act like this. The pcm will command downshifts based on throttle % and vehicle speed regardless of what manually selected gear you have, and the downshifts can be a bit harsh on the tapshift transmissions when the pcm has to do the work for you. If the car is in D range then it should never take off in 2nd gear from a dead stop and then as you accelerate from the stop drop back into 1st.