'02 V70XC: TCM update + valve body questions Topic is solved

[leapdragon]

Hi all,


Been a while, hope you've all been well!

My '02 V70XC has developed a 2-3 shift flare. Right now when we drive it, we are letting off the accelerator right around 2-3 shift point so that it doesn't flare before locking up into 3. It holds 3 fine once it's there.

Have replaced fluid, even though fluid wasn't that old. No dice, issue remains.

So I have a few questions:

(1) A common point in the question/answer threads about valve body replacement is "Have you updated to the new TCM software?" I know that some of the TCM update revisions were in part addressing 2-3 flare, but how much does having the latest TCM software help in the real world?

Instinct says "don't bother, software fixes are mostly invisible" but if any of you are about to yell "hey that TCM update might well solve your 2-3 flare" then please let me know and maybe I'll drop the $100ish for the 3-day VIDA sub + software update and go through the pain of running that before trying anything else.

(2) My impression from reading through the valve body replacement write-ups is that it's not actually all that bad if you've got the tools and a hoist to hold the engine while the subframe is lowered, maybe similar irritation and difficulty level overall as a PCV service. Fair? Just want to be sure I'm not significantly underestimating the difficulty.

(3) My impression from reading through the endless posts is that matching valve body revisions doesn't actually matter, i.e. later versions physically mate up fine to earlier cars, the difficulty is mainly around wiring (specifically, wiring harness length and the need to extend wires). True?

For example, from my reading, I seem to understand that you can purchase GM/AC DELCO PN #24228787, swap S2 solenoids and remove the B5 control spring, and then use it to replace any P2 V70 valve body revision fro start to end, so long as you handle any wiring issues. Can anyone confirm?


Thanks in advance for your help, all, this forum remains my go-to source for P2 expertise!

[dikidera]

You could've been my guinea pig . I have quite a few software changes I can do in the TCM to try and solve it. I guess my first one would be a higher fill time or higher fill pressure of the hydraulic chamber.

While I have not yet played around with the off going clutch its also a possibility that it releases too early.

But yeah a valve body will very likely fix all of that in one go.

[leapdragon]

Dikidera,


So it doesn't sound like you're talking about the software update PN #30677036 from Volvo, true?

I'm happy too be a guinea pig if you need one, and would love to here where/how it's possible to play with parameters like fill time/fill pressure, etc. I presume for the B4 servo? Unless it's a matter significant hardware/software hacking, in which case I'm too old for that now.

[dikidera]

No I am talking about actual tuning, especially for 2-3 since rather than having a flare I am trying to make it as smooth as possible so all my focus has been on the 2->3 shift. In fact I have a beautiful shift at very low RPM, but a harsher at higher RPM. I will be trying to cause a flare myself by causing the offgoing clutch to release a bit sooner.

While nice, I have no way of flashing these changes for you, not even with a VIDA subscription.

[firstv70volvo]

Hi all,


Been a while, hope you've all been well!

My '02 V70XC has developed a 2-3 shift flare. Right now when we drive it, we are letting off the accelerator right around 2-3 shift point so that it doesn't flare before locking up into 3. It holds 3 fine once it's there.

Have replaced fluid, even though fluid wasn't that old. No dice, issue remains.

So I have a few questions:

(1) A common point in the question/answer threads about valve body replacement is "Have you updated to the new TCM software?" I know that some of the TCM update revisions were in part addressing 2-3 flare, but how much does having the latest TCM software help in the real world?

Instinct says "don't bother, software fixes are mostly invisible" but if any of you are about to yell "hey that TCM update might well solve your 2-3 flare" then please let me know and maybe I'll drop the $100ish for the 3-day VIDA sub + software update and go through the pain of running that before trying anything else.

(2) My impression from reading through the valve body replacement write-ups is that it's not actually all that bad if you've got the tools and a hoist to hold the engine while the subframe is lowered, maybe similar irritation and difficulty level overall as a PCV service. Fair? Just want to be sure I'm not significantly underestimating the difficulty.

(3) My impression from reading through the endless posts is that matching valve body revisions doesn't actually matter, i.e. later versions physically mate up fine to earlier cars, the difficulty is mainly around wiring (specifically, wiring harness length and the need to extend wires). True?

For example, from my reading, I seem to understand that you can purchase GM/AC DELCO PN #24228787, swap S2 solenoids and remove the B5 control spring, and then use it to replace any P2 V70 valve body revision fro start to end, so long as you handle any wiring issues. Can anyone confirm?


Thanks in advance for your help, all, this forum remains my go-to source for P2 expertise!

Before considering the valve body and because this is 2-3rd flare I'd do a B4 servo service first, o-rings or the update kit. Do you have any other problems with the transmission shifts, are the garage shifts okay?

[leapdragon]

@firstv70volvo Garage shifts vary from happy to iffy, most of the time average, every now and then there's a hard one. B4 servo has been updated but it's been some years. I thought about O-rings, but I actually have no idea where to find them.

Anyone have a part # for a B4 servo o-ring kit?

As far as the shifts go, it's more or less:

1->2 good
2->1 good
2->3 flares unless RPM matched with accelerator pedal
3->2 good
3->4 mostly good, sometimes slight shudder
4->3 good
4->5 good
5->4 good

So basically, it's the 2->3 and 3->4 that have issues. 3->4 is what I'd call barely noticeable, but 2->3 has recently become a guaranteed flare every time unless you partially let off the accelerator at the top of 2 in anticipation of the shift. Tried going into VIDA (offline version) and putting car into adaptation, but I was unable to get a flash for the 2->3 shift at all, despite an hour or so of trying at various throttle levels.

I did pull the B4 servo out, clean everything in that area well, and polish the pin a bit with diamond lapping paste (it was showing wear and a bit rough in texture) but that doesn't seem to have helped. I know there's a discussion of pin length for this servo, but it doesn't look like this pin has lost more than 0.5mm or so off the tip, and the 3-4 slight hiccup tells me maybe it's not pin length, i.e. it's slow to disengage as well, so probably line pressure isn't good enough for B4 to move it in either direction.

O rings when I took it out were unimpressive in two senses of the word, first no damage or obvious wear, but second also a bit loose and small feeling for my taste. However, that could be normal. I thought about replacing the O-rings, but I didn't find a ready source apart from buying the full B4 servo kit, which I hated to do just for new O-rings.

If you've got a source/link, would love to give that a try.

[leapdragon]

So following up, I've just gone to Amazon and purchased 45.2 and 47.2mm inner diameter 2.4mm cross-section fluorine rubber o-rings. We'll see if either set comes close to what's in there now, easy enough to give this a try first. Thanks for pointing this out @firstv70volvo, I forgot I'd started down that road and then let it go...

[firstv70volvo]

So following up, I've just gone to Amazon and purchased 45.2 and 47.2mm inner diameter 2.4mm cross-section fluorine rubber o-rings. We'll see if either set comes close to what's in there now, easy enough to give this a try first. Thanks for pointing this out @firstv70volvo, I forgot I'd started down that road and then let it go...

Here's the B4 servo update kit that should work with your car
https://www.fcpeuro.com/products/volvo- ... 549fe76b6e

[leapdragon]

I did the B4 update years ago so it would just be a question of have the o-rings degraded, OR can I play with the o-rings in terms of thickness and/or material and extract some different behavior from that servo...

[dikidera]

Well I'd hazard a guess that either the pressure isn't high enough when it needs to be to hold down the new gear or the car disengages the gear too soon. Could be both true at the same time.

The gearbox goes through this process, it initiates a clutch fill process, whereby the hydraulic circuit is filled with oil for some time and with a particular pressure.



Here is how it looks exactly for 2-3, obviously variations will occur as each shift 2-3 shift is always going to be different than the one before it.

The olive green color represents the pressure for the oncoming clutch. The blue represents the pressure for the offgoing clutch. The green line is RPM.

At the junction where the blue line is dropping and the olive green is starting to go up is I where torque handoff happens.

Lets assume here that for some reason it's the olive green color, the pressure for the oncoming clutch that is not quite right. It could be that the pre-programmed fill time is not enough. It could be that the fill pressure is not enough. It could be that the ramp pressures are no longer enough.

Btw, adaptations strongly affect the properties here as well.