Another PB auto limp mode

[old Jack]

Yes the changes are positive. I have been able to get the same behaviour with cruise control off but I really have to concentrate on keeping the accelerator steady and not apply too much. I have noticed that at 110kph GPS the down changes seem better than at 100kph GPS.

OJ.

[SwampFox55]

Yes the changes are positive. I have been able to get the same behaviour with cruise control off but I really have to concentrate on keeping the accelerator steady and not apply too much. I have noticed that at 110kph GPS the down changes seem better than at 100kph GPS.

OJ.

After reading the last few posts (especially OJ’s post 118 and KevL’s post 120), yesterday arvo I drove my PB auto up a 15 degree hill about 800m long at the 90kph posted speed limit, to get a baseline of operation with which to compare my tranny’s pre-mod. software against the other posted results and the post mod. software operation. I had to drive 25km to find a suitable steady incline.My car’s last service was in March and it is behaving exactly the same as OJ’s used to and KevL’s does now.

The critical point is that the tranny would not auto lock when my foot was controlling the accelerator pedal but it would auto lock with cruise control selected.I made three runs using the different methods described below.However, on the third run I engaged cruise control for comparison purposes with OJ’s post and it did exactly the same as his tranny used to, with a noticeable unlocking event between the two lock-ups.Normally, I’d never attempt to drive uphill with cruise selected so I have missed this tranny behaviour in the past. Yesterday, when I drove uphill while manually controlling the throttle I tried very hard to maintain a steady 90kph.The results confirm what OJ used to see occurring in his transmission, pre-mod.

After all this, the question for me is, because this operation only works with cruise selected (for practical purposes) is this mod. of any real consequence? Even before the mod. the tranny is going from locked in 5 to locked in 4 but just with a fluctuation to 2900/3000rpm for a couple of seconds between lock-ups.I suspect this brief unlocked condition is to ensure a smooth shift and reduce wear and tear within the tranny.Is this lock to lock operation (both pre and post mod.) going to make me abuse the drive line and tow in undulating country with cruise selected, I think not!Remember, most of the bitching has been about the tranny continuing to run in an unlocked condition (both in Drive and Sports modes) when towing because when not towing, it’s acceptable, not perfect but acceptable, for a poorly designed setup.

Results:

1. Drive Mode.In Drive, soon after starting uphill (eg 200m after the incline commenced) the rpm suddenly went from 1700 to 3000 for a second and then settled at 2700. I then pressed the throttle to the floor and the rpm went to 4300 but there was only slight acceleration – due to the uphill load.I resumed the previous throttle position and selected Sports mode to check which gear it was in and it was still in 5.I changed down to 4 and the rpm remained much the same at 2700 (4 unlocked).

2. Sports Mode.In Sports mode in 5, at about the same position on the hill the rpm suddenly spiked again from 1700 to 2900 and settled again at 2700.As before I down-shifted to 4 and the rpm remained at 2700 (4 unlocked). I then lifted the accelerator pedal to drop the rpm and picked it up to lock it in 4 at 2400rpm – by the time it got back to 90kph a few seconds later. I then pressed the accelerator pedal to the floor but the rpm didn’t change and the acceleration was extremely poor – due to the uphill load. It did not change down and it did not unlock.After a few seconds I reduced throttle and continued uphill normally.

3. Drive with Cruise Set.As before in Drive but this time with Cruise Control engaged.The throttle opened when starting up the hill but the tranny didn’t unlock from 5 at the same position on the road but about another 100m (3 or 4s) further uphill.Therefore it was already behaving quite differently compared to manual throttle control. When it unlocked in 5 the rpm again spiked from 1700 to 2900 for a couple of seconds but then dropped to 2400 and remained stable.I selected Sports mode to find it in 4 locked. Within 4 seconds it had gone from 5 locked, to unlocked, then locked in 4 – as OJ mentioned in his post 118.I then repeated the locked 4 acceleration test as above with the same result.

Summary.In Drive without cruise engaged, when the tranny unlocked it remained unlocked in the same gear.It would have remained in this state if the conditions didn’t change, as per the long even slope I used yesterday.There are plenty of places where there are steady long climbs eg the Hume Freeway.However, when cruise control was engaged before driving uphill, the tranny automatically down-shifted and then locked.Now remember this is occurring with the original software.My PB’s build date is mid ’12 and the last software update was in March.

Conclusion.The fact that with cruise control selected the tranny is going from locked in 5 to locked in 4 is totally unexpected but still impractical for normal use because its poor practice to leave cruise set when driving uphill. I’m certainly not going to tow uphill with cruise set just because it will change down and lock in 4.If the new mod. avoids the spike to 2900rpm when the tranny goes unlocked it really is a moot point as this condition only lasts for a few seconds. If the software is to have any real benefit it should operate from locked to locked without cruise set. However, OJ is saying it doesn’t unless he tries really hard to maintain a steady accelerator position – that’s just user unfriendly for most people. So, it’s of no real benefit over the existing condition, if indeed it is an intended consequence.If on the other hand it operates when a driver is manually controlling the accelerator pedal in a normal manner, it would then be magic!Yes, I was hopeful for a couple of moments until I re-read OJ’s comments in posts 118 and 121 after doing the test runs.

The Future. Don’t hold your breath hoping for a mod.If you can’t live with it just buy a PS.I’ve had a good hard look at all the competition and it came down to hopeless cargo bay floors (eg high, uneven and sloping folded seat backs) in the Everest, MUX and Trailblazer and the Fortuner’s overly firm suspension - will await the revised interior in the 2018 PS.


SF55
161016

[old Jack]

Ok, I did a run up the SE Freeway to Monarto and back this morning, combination of the very steep climb from the Tollgate to Crafers and then 40km each way though the hills that have long climbs and descents.

Monitored with my TC dampener solenoid voltmeter and Scannguage II set on rpm, LOD, ATF temp and coolant temp. I have found I can replicate the downshift behaviour that occurs in cruise control with manual accelerator but it is sensitive because the AT ECU is not only looking at accelerator postion but also theoretical engine load.

At 110kph GPS in locked 5th engine is doing 2240rpm and in locked 4th it is doing 3070tpm. The trans will change down in both "Drive" and semi manual mode in 5th, back to 4th unlocked for less than a second and then to locked 4th when the engine load gets to 80%, however if the load does not drop below 75% to 77% within about a second of the downshift then the TC will not lock up in 4th until the load is less than 75-77%.

It is an improvement on the previous AT program, I just wish MMAL could access the AT program like MMC can.

OJ.

[itsamitsi]

OK, so the wash up of this is a software update for the AT is available at MM dealers yeah?

[fester]

If you can’t live with it just buy a PS

Better yet buy a real Pajero.

[old Jack]

OK, so the wash up of this is a software update for the AT is available at MM dealers yeah?

Yes it is the latest version that all Dealers should have.

OJ.