[Voldsom Volvo]

So I have had this "issue" for as long as I can remember.

When setting the cruise control at 70kph/44mph it sometimes stays in fourth gear and around 1900rpm while on other occassions it will shift up to fifth gear and around 1400rpm.

Sometimes I need to adjust it (via cruise control) all the way up to around 82kph/51mph before it decides to shift up to fifth.

The oil was changed about 12K miles ago when the gearbox was taken apart due to a worn down clutch plate. The mileage at that time was only around 60K miles. The issue with the indecisive shifting was there before the transmission refurb as well.

Two questions in this regard:

1) Will a new software update fix this? Last time I had the car updated via service was about 2 years ago.

2) Will the indecisive shifting between 4th and 5th gear with cruise control on cause unnecessary wear on clutch plate?

Help is much appreciated!
Chris

 

[MyNameIdeasWereTaken]

While I don't know how it will effect your car, I will say that the automatic shifting is mostly based on your driving.

When not in cruise, you can quickly pop off the gas pedal to shift up, or quickly stomp down to shift down, or floor it past the little click and it'll shift into the lowest gear it can get into.

Our cars learn our driving habits, so if you generally like the car to shift at higher RPMs, it will hold off shifting longer. If you drive it like a grandma, it'll shift really early. And of course, given time, it'll change that around based on your "recent" driving habits.

I always use the GT, I don't like automatic cars... and I rarely use cruise. But my guess would be that cruise control is just trying to drive based on how you've recently driven. Just my guess though, I may be wrong, so please let someone else chime in too.

 

[Voldsom Volvo]

Thanks. Makes sense. Just wouldn't think it would affect shifting in cruise control mode.

Anyone else care to chime in?

 

[Voldsom Volvo]

Calling all automatic experts - feel free to comment

 

[Pana]

Tested this out on my car today - 75000km - has not had a fluid change or a software update for at least 2 years

CRUISE OFF
60kph - 4th
65kph - 5th

CRUISE ON
60kph - 4th
70kph - 4th
80kph - 5th

Even when I was driving at 70kph with Cruise OFF and in 5th, if I set the cruise on at the exact speed, it would downshift to 4th as soon as cruise was on.

Did not get a chance to try it in manual mode to see what it would do.

 

[MyNameIdeasWereTaken]

Hmm... I've never driven either of my S40s in automatic, only geartronic. So maybe that's why I seem to have different results. I would only engage cruise once in 5 gear on the highway. Though, I would also set cruise at 79mph... But I have played around with cruise around 60, I don't remember how it behaved there though.

 

[shadowlord]

im glad im not the only one with this issue, i have 130k miles and i ever since i bought the car 4 years ago it has been doing the same. right around 43mph it will shift to 4th gear and if you increase the speed it will stay in 4h until around 52-53mph no matter for how long you drive in 4th gear. i find it really annoying. if i have to cruise at aorund 40mph i usually up shift to 5th gear and i keep it in manual mode, so that way it stays in 5th. I never had software update and i changed my fluid couple times already.

 

[navolvo]

Does your transmission downshift when coasting down hill? I sampled a C30 before and it downshifts from 5th to 3rd while going down, but my car doesn't do that.

 

[Pana]

Does your transmission downshift when coasting down hill? I sampled a C30 before and it downshifts from 5th to 3rd while going down, but my car doesn't do that.

Nope, no "grade logic" on mine either.

Sent from my HTC Desire S using Tapatalk 2

 

[EngTech]

im glad im not the only one with this issue, i have 130k miles and i ever since i bought the car 4 years ago it has been doing the same. right around 43mph it will shift to 4th gear and if you increase the speed it will stay in 4h until around 52-53mph no matter for how long you drive in 4th gear. i find it really annoying. if i have to cruise at around 40mph i usually up shift to 5th gear and i keep it in manual mode, so that way it stays in 5th. I never had software update and i changed my fluid couple times already.

I'd say it is a Function Item , as If You were Towing this is how it should be operating . It would be nice to actually Test that out .
The other Item , I would think a Tuned ECU - knowing the Motor is putting out more Tq. would simply shift sooner then stock . It clearly sounds like it isn't , so this also , points to Towing .

( Big need for a Shift Kit )

As far as Cruise Mode at 40 MPH , can't think of any reason to do that - If a Speed sign say 40mph - I go - 45mph seems like it would Hold at that Speed .
There is a Company that makes Performance Items for these Transmissions , sound like time for a Shift Kit .

 

[Voldsom Volvo]

Thanks all for comments so far.

Tested this out on my car today - 75000km - has not had a fluid change or a software update for at least 2 years

CRUISE OFF
60kph - 4th
65kph - 5th

CRUISE ON
60kph - 4th
70kph - 4th
80kph - 5th

Even when I was driving at 70kph with Cruise OFF and in 5th, if I set the cruise on at the exact speed, it would downshift to 4th as soon as cruise was on.

Did not get a chance to try it in manual mode to see what it would do.

Your experience with the cruise on is is exactly how my car reacts as well. Have not observed its behavior when cruise is off, so will need to do some testing.

Pana, is your car tuned?

im glad im not the only one with this issue, i have 130k miles and i ever since i bought the car 4 years ago it has been doing the same. right around 43mph it will shift to 4th gear and if you increase the speed it will stay in 4h until around 52-53mph no matter for how long you drive in 4th gear. i find it really annoying. if i have to cruise at aorund 40mph i usually up shift to 5th gear and i keep it in manual mode, so that way it stays in 5th. I never had software update and i changed my fluid couple times already.

Thanks for sharing Shadowlord.

Seems you also have the same issue. Try this though. With cruise on keep increasing speed until it engages 5th gear (i.e. at 52mph). Once it has shifted up, still with cruise on, decrease speed to i.e. 44mph - does it stay in 5th gear?

NEW QUESTION:

How much torque/HP is the T5 engine in our cars putting out at say 1400 RPM? The reason for asking is that I am wondering whether I would actually be putting a strain on the engine by keeping at such low revs.

 

[Beck]

Low revs do strain engine and transmissions.

 

[ifnt420]

Doesn't the AW55 GT torque converter lock up in 5th at around 40~45mph?　
If so, that would explain why it stay in 4th and sometimes in 5th like you've experienced.

Normally, if i keep the speed around 40mph, I can feel the transmission hunting in between the two gears.
Therefore, I just either go faster or slow down a bit.

 

[Pana]

Pana, is your car tuned?
Seems you also have the same issue. Try this though. With cruise on keep increasing speed until it engages 5th gear (i.e. at 52mph). Once it has shifted up, still with cruise on, decrease speed to i.e. 44mph - does it stay in 5th gear?

NEW QUESTION:

How much torque/HP is the T5 engine in our cars putting out at say 1400 RPM? The reason for asking is that I am wondering whether I would actually be putting a strain on the engine by keeping at such low revs.

No tune - engine is completely stock.

My GT will shift back to 4th at 44mph/70kph when Cruise is on. It will stay in 5th with cruise off.

Also from memory - the 06 T5 is at full Nm from 1500rpm to something like 4000 something rpm - may be wrong though - happy to be corrected

Low revs do strain engine and transmissions.

Agree - question is why the different behaviour whether cruise is on or off?

Doesn't the AW55 GT torque converter lock up in 5th at around 40~45mph?　
If so, that would explain why it stay in 4th and sometimes in 5th like you've experienced.

Normally, if i keep the speed around 40mph, I can feel the transmission hunting in between the two gears.
Therefore, I just either go faster or slow down a bit.

Mine will lock up at 40mph/65kph in 5th - very light throttle will unlock the torque converter and it will accelerate slowly in 5th - any more pressure and it will drop down to 4th. I can occasionally make the engine labour doing this if the torque converter doesn't unlock immediately which it sometimes doesn't - apparently a software update will fix this (so told by Volvo Australia)

 

[Voldsom Volvo]

Thanks Pete. Full torque (give and take) already from 1500 RPM sounds plausible. The BSR graph for T5 tune only shows output starting from 2000 rpm, but the stock torque seems to be quite flat throughout the range. BSR output is definitely more spikey.

Doesn't the AW55 GT torque converter lock up in 5th at around 40~45mph?　
If so, that would explain why it stay in 4th and sometimes in 5th like you've experienced.

Normally, if i keep the speed around 40mph, I can feel the transmission hunting in between the two gears.
Therefore, I just either go faster or slow down a bit.

Thanks. Could you define torque converter lock up?

The transmission hunting in between the two gear is what I am experiencing as well. I seem to recall a transmission specialist telling me this is not good for the transmission - someone care to confirm?

 

[Pana]

Thanks. Could you define torque converter lock up?

Probably easiest way to describe it is
Torque converter unlocked - like clutch slipping in a manual transmission
Torque converter locked - like you are accelerating in gear with a manual transmission

Here are some videos I took on the way home...

Torque converter unlocked


Torque converter locked

 

[kova]

NEW QUESTION:

How much torque/HP is the T5 engine in our cars putting out at say 1400 RPM? The reason for asking is that I am wondering whether I would actually be putting a strain on the engine by keeping at such low revs.

You shouldn't be worried about that because ECM is also monitoring a paremeter called "engine load" and will inititate downshift to raise torque when needed.

That can, however, be an issue with manual gearbox in which case it is responsibility of the driver to act accordingly in such situations.

 

[Voldsom Volvo]

Thanks Pete. I think I know what you are getting at.

You shouldn't be worried about that because ECM is also monitoring a paremeter called "engine load" and will inititate downshift to raise torque when needed.

That can, however, be an issue with manual gearbox in which case it is responsibility of the driver to act accordingly in such situations.

Thanks, yes I expected this to be the case as well.

However, since the auto transmission seems to shift a bit erratically as described with the 4th/5th gear situation, I'm a bit worried that it might screw up minimum revs/engine load as well

 

[kova]

Thanks Pete. I think I know what you are getting at.

Thanks, yes I expected this to be the case as well.

However, since the auto transmission seems to shift a bit erratically as described with the 4th/5th gear situation, I'm a bit worried that it might screw up minimum revs/engine load as well

I wouldn't worry if I were you, the algorithm is probably trying to optimize for fuel consumtion. If it couldn't get enough torque from current gear to cover the load it would downshift immediately.

 

[Voldsom Volvo]

Thanks.

I always run Shell V-power Octane 99 (RON) for maximum performance and economy. I am told this fuel primarily due to higher octane gives maximum engine output - especially when tuned. So assuming the engine has greater power overall (even at lower revs) can I assume this could cause the engine management to run at lower revs than that of a stock engine - as it will have i.e. more torque to withstand?

I will have to do some testing with and without the tune. But just like Pete (Pana) mentioned with his stock T5, I seem to recall that with mine in stock mode it would not go into 5th gear at 70kph/44mph in cruise control mode either - whereas at least sometimes it chooses to do so now, with the tune.