4200/GP/QP Transmission and Ancillaries

[conaero]

Ah, just had a thought. The new gearbox will have different characteristics to old one and your TCU is set up for the old one maybe?

I take it you have done an actuator relearn? It will cycle through all gears (whilst stationary) and set the shift max and min peramiters?

 

[spn]

What was the gearbox parameter called you used to monitor the bite point?

I listened to the engine note.

 

[Gp79]

Ah, just had a thought. The new gearbox will have different characteristics to old one and your TCU is set up for the old one maybe?

I take it you have done an actuator relearn? It will cycle through all gears (whilst stationary) and set the shift max and min peramiters?

100% will need full set up

 

[lambertius]

Full relearn was done, PIS has been redone. After a bit of faffing about the last few days I've gotten my car to the point:

1) Drive normally, shift low RPM, don't lift your foot off the throttle. This is the loudest and most uncomfortable scenario.

2) Drive aggressive, shift only above 4000 RPM, don't lift your foot off the throttle. Shifts are quieter, faster and smoother.

3) Drive like a manual without a clutch. Pull the lever, lift off entirely until in gear, then accelerate again. This is like driving butter.

I don't remember having to drive like that in other Gransports, but if that is just the way then I'm also okay. I am really just trying to work out where the endpoint on this quest is!

 

[mjheathcote]

You certainly should not have to lift off when changing gear.
Even the Maserati official "how to drive a cambiocorsa" video tells you that you should not lift off.

 

[lambertius]

Thanks for sharing that time warp!

I've run the car off the ground and can't see any play - but its hard for safety reasons. Tomorrow I'll try again and put some cameras under the vehicle rather than risk death, but I'm not expecting to see anything else.

I've been doing some thinking and it really does feel like the car isn't synchronising the clutch on upshifts (it blips and matches very well on downshifts). That would explain why its so smooth when I lift off the throttle, I'm manually rev matching like you would in a... manual...

Does anyone have any idea of some sensors that I should explore or chase down?

 

[tulit]

Just to note, my 06 Gransport also only detects/connect with "First Version". It hasn't had its TCU replaced. I don't think its conclusive that it matters if its first/second version per the X431

 

[tulit]

FYI here are all the version numbers:

So the other GS you looked at seems to be using the older software.


Sent from my iPhone using Tapatalk

 

[lambertius]

Just to note, my 06 Gransport also only detects/connect with "First Version". It hasn't had its TCU replaced. I don't think its conclusive that it matters if its first/second version per the X431

Oh that is super interesting! I'm betting you have the same module installed as I do then! Good to know it is a common behaviour! I take it you're running the same MCC49 software version as me then?

I guess that brings the question down to driving style as the only other diagnostic path to follow?

 

[lambertius]

I bought a GoPro mount that I can get under the car, I'll take it for a few runs and see if I can see anything happening, but I don't think its movement in the parts.

I might try and get a GoPro headband as well so I can show you what is happening, as I'm pretty confident I know what is causing the harsh shift in a mechanical sense. I found somewhere really quite where I could just up shift and down shift without annoying anyone and I did that for a while. The car absolutely is not rev-matching on upshifts, but is revmatching on downshifts. Keeping in mind that it is a manual gearbox, it behaves like one when you shift. If I don't lift off then the RPM continues to climb making the shift harsher when the clutch engages. When I've been lifting off I've been doing the rev matching manually smoothing out the problem. It also explains why the issue is more pronounced at lower RPM, when the shift takes longer to happen.

So for everyone else, when you pull to up shift, does the RPM drop on the engine to match the engagement? Assuming it does, then I've got a direction to chase the issue!

Then the trick will be working out what sensor is meant to be feeding that information to the TCU that is getting missed. Or conversely, what command the TCU is sending back to the ECU that is getting missed.

 

[lambertius]

Framing is a bit weird, and I couldn't mount the camera on the actuator side. That said, nothing I could spot going on under the car.

 

[lambertius]

There it is, engine RPM and gearbox input rpm diverge after first gear.

Anyone got any ideas?

 

[Zep]

Did you measure this while running the car off the ground?

I ask because the gearbox speed drops rapidly which would not be the case while driving on the road due to the momentum of the vehicle rolling.

 

[lambertius]

Riding shotgun while my fiancee drove me to the dentist. Focusing on the important stuff

 

[midlifecrisis]

FYI here are all the version numbers:

So the other GS you looked at seems to be using the older software.


Sent from my iPhone using Tapatalk

It would be interesting to have the software versions of the GT too, where did you get this from?

 

[Zep]

Interesting then that the gearbox speed drops to zero during the shift. Assuming it is measuring the input shaft speed then perhaps there is some drag on the torque tube bearings or input bearings.

 

[CatmanV2]

Well surely

Interesting then that the gearbox speed drops to zero during the shift. Assuming it is measuring the input shaft speed then perhaps there is some drag on the torque tube bearings or input bearings.

Forgive me, but when the gearbox speed is zero, isn't the car at idle?

<expects to be very wrong>

And if the gearbox speed is appreciably lower than the engine speed, must be loss of rotations somewhere? Clutch slip

<expects to be evenr wronger>

C

 

[Zep]

Well surely


Forgive me, but when the gearbox speed is zero, isn't the car at idle?

<expects to be very wrong>

And if the gearbox speed is appreciably lower than the engine speed, must be loss of rotations somewhere? Clutch slip

<expects to be evenr wronger>

C

That would be one reason. The graph seems to show a gear shift, so it is spinning at engine speed, the stops and then spins again after the clutch has re-engaged.

What we don’t have is a graph of a “good” gear shift, so it may or may not be an issue. But it does seem a bit strange.

 

[CatmanV2]

I thought the graph shows 5 shifts, from 480 whatevers on the x-axis from a standing start (Gearbox at 0, engine revs at 900 sih)

C

 

[lambertius]

Hey guys,

Catman is correct. That is a graph of four gear shifts. The car starts stationary which is why the input on the gearbox is zero. The four spikes are four gear changes. Each gear change the engine keeps revving up when the clutch is disengaged making the shift harsher - just like not lifting off in a manual.

The x-axis is seconds.