Momentary power loss when upshifting
 

Alright, an intermittent puzzler for the brains trust:

I've noticed that on normal acceleration there is what seems like a brief (less than half a second) cut to power just after it changes from 2nd to 3rd. I can't seem to replicate it on demand, but I've noticed it more regularly in recent weeks. Gave the MAP sensor a clean and it hasn't helped (it was clogged though, even with the catch can), I might give the MAF a squirt too. Transmission is due for its ~100k oil change, but it really seems like a loss of power rather than anything gearbox related. Funny that it seems to only happen when it slots into 3rd though.

Not a big issue at all and it's completely manageable, but it's starting to annoy me. Hoping it isn't a sign of anything sinister. Any ideas?

Long shot but easy to check. Have you tried turning your iDrive off?

Funny, that just went through my mind too LeCheese. Any possibility it could be related to that 'dead spot' you mentioned in the iDrive thread?

Yes sorry, meant to mention in the initial post but it slipped my mind. First thing I tried was turning it off but it doesn't seem to make a difference - if anything it's maybe a bit more noticeable.

Is it noticeable when going down the box at all ??? If so it could be a sticky solenoid especially if this 100K service is its first........... I would unplug the i Drive as even off but plugged in they could still be online.......... The old disconnect battery, flick switches to clear residual power along with unplug TCM then connect back up might clear any memory..... I do know unplugging the TCM is needed to clear it, can't recall where I read it though.

Mine actually did something similar one morning but with 4-5, I was moving slowly, box temp was only about 45, tried to get it to do it again and nothing so I put it down to it was too early in the morning....

Doesn’t do it downshifting as far as I’m aware, but not often that I’m in a speed range for it to shift down from 3rd to 2nd under load. I’ll give it a test manually.

I think it’s been more consistent in the cooler weather, but could just be a coincidence. I first noticed it earlier in the year when it was still warmer weather, and the vehicle had been driving for about 20min as well

Get the service on it might be what is needed, mine has been quite happy with Penrite BMV in it, even in some cold Canberra weather it changed the same for a cold box, mine being a QLDer that lives inside when not on the road grumbles a bit when left outside in the cold of Canberra, just a grumble to show its displeasure I think but settles down in a hundred yards...............