C5 X7 3.0 240 HDi - Transmission acting weird

[tredy]

Hello! so I've been noticing a weird behaviour of the AISIN AM6C automatic transmission of my C5 X7 3.0 HDi:

usually in 3rd gear when I accelerate a little more than normal the rpm's go slightly and suddenly up and stay there for a very short while before going back and continuing their regular acceleration

So far I've noticed it only in the 3rd gear, car has 137K km, transmission oil was changed 20K km ago but it has been doing this behaviour since I changed it, not sure if also before.

any idea or suggestion what it could be is very helpful!

[xantia_v6]

Sorry misread the post.

What year is your car?

[NewcastleFalcon]

While you are waiting for someone with more knowledge than me to contribute, I have some experience of a version of the same Aisin Box fitted to a Vectra.

The only intervention unless your are a 5 spanner mechanic not phased at replacing solenoids/valve bodies or stripping and rebuilding the box, is making sure that the fluid is the right specification for the box, and that the level has been set correctly.

I found with My Vectra that I could adjust my driving to minimise any tendency to "flare" which is the symptom you describe you can almost anticipate it happening and back off the revs slightly. Not a cure of course.

You say the ATF was changed 20K miles ago. Do you know the spec of the fluid put in at the time, who did it and did they follow the approved procedure including reseting of the oil counter. Was it flushed which could have caused redistribution of any debris or just drained and refilled. The boxes do have a filter but its internal and requres dismantling to access. Is the replacement fluid still a nice bright red colour or does it smell burnt and black. Has there been any water ingress into the fluid via any cooler arrangement it may have, or indeed have you driven through floodwater ( certainly in the Vectras case reports of water ingress via breather tube)

Others may have more helpful information but making sure you have the right fluid in it, and its the right level is probably the first stage.

Regards Neil

[tredy]

C5 is 2010 model, oil is "Champion eco flow 3014" (I read the specs they were right: JWS 3324), change was done by professional with the specific machine that injects and pushes out old oil, oil counter they told me was reset.

What else is there to reset? (i remember the accelerator something parameter?)
Any expert can tell me if there is a software update for the transmission?
any other help is welcome!

[GiveMeABreak]

You actually have a 2009 model (build date 24 September 2009) for reference.

Do you have any warning lights on the LCD display, or have you run a diagnostic to see if there are any reported codes?
P1733 is a code that would be produced for general slipping of the gearbox.


The oil is JWS3324 spec., so that is correct for your vehicle.

Also, make sure you have the same sized tyres on all wheels and they are correctly inflated - this can affect speed readings / variances that can affect the gear changes.

[white exec]

Could flare (on acceleration) be mistaken for a momemt of drop-down, or just the torque converter unlocking then locking up again, either of which would produce an increase in engine revs, which would drop again when the accelerator is eased off?

[Stickyfinger]

This I think..."the torque converter unlocking then locking up again", mine has always had a little increase/decrease.

[tredy]

You actually have a 2009 model (build date 24 September 2009) for reference.

Do you have any warning lights on the LCD display, or have you run a diagnostic to see if there are any reported codes?
P1733 is a code that would be produced for general slipping of the gearbox.


The oil is JWS3324 spec., so that is correct for your vehicle.

Also, make sure you have the same sized tyres on all wheels and they are correctly inflated - this can affect speed readings / variances that can affect the gear changes.

excellent reference thanks!
no warnings but I haven't run a scan yet also because it seems as if it is how the gearbox works or how the software makes it work, are you aware of any transmission software updates by any chance?

[GiveMeABreak]

I can't advise on that - you would have to know your current version (from using Diagbox). You'd then have to get it to a dealer who would do the same and see if there was an applicable update from their servers, based on your exact vehicle specs.

I say applicable update as they normally don't upgrade the software in general - unless there is a reason, like a technical service bulletin, as doing so can cause issues with other systems that talk to the gearbox ECU (like the ESP, engine ECU, BSI etc.).

An example of this is on the X7 - if you get your BSI updated, it will deactivate the automatic memory indexing functions of the rear view mirrors in reverse gear if you have that option on top spec. vehicles circa 2009. This was due to a European ruling (groan) that decided that cars with indexing mirrors would not allow the driver to see persons or objects behind the car if the mirrors were pointing at the kerbs! This - despite these spec'd cars having rear obstacle detection in addition.... another crazy ruling.

So they changed the categorisations and stopped offering the feature on later vehicles. But sneakily, they updated the software in the BSI to disable the feature and onlyput the info into a technical service bulletin to say it is normal behaviour from a certain build date and that the function has been deactivated.

So the only way to see if there is an update is to pay the dealer for a diagnostic - or get a service done at the dealer which should include any routine updates - but specifically ask them to check for this. On some vehicle models / options / specs. they won't apply an update if the software is already at a sufficient level if it will have no, or a detrimental affect.

[jgra1]

I cant help Tredy, except mine flares more than a group of passengers on the Titanic! (bit soon?)
It's always done this, I have no idea what a good box feels like! I think I am missing out a lot

Mine also no longer selects 6th by itself, except on the second Tuesday of the month at 8.02 am .. fifth is going the same way.

It also makes a whirring noise in 6th at around 40mph (although I am not bothered by this)

I did a partial oil change and decided more was a waste of money.. I think mine has been neglected for too long. Car used to tow a caravan as well.
bought at 120K now on 160K

John

[marsalek]

Hi tredy,

I noticed the very same behaviour (AM6 C5X7 HDi240) and was just about to post today the same question as you . Whenn accelerating, it shifts from 2nd to 3rd. The revolutions in the 3rd gear increase (unlocking?), stay there for a while and then drop down (locking?). Later it shifts into the 4th. I was also wondering, if it could be the torque converter unlocking and then locking up again.

I also noticed, when in 3rd drving "quite slowly" (maybe just above 2000 RPM) and push the gas pedal to accelerate, the revs increase suddenly for a while and as soon as the car speeds up a bit, the revs go down again (still in 3rd). Without having any knowledge of the gearbox control SW, I have the impression it is really on purpose and by increasing the slip in the converter the engine gets higher torque and is probably even more fuel-economical.

My mileage is 150 000 km, did a partial ATF change summer this year with 12 liters of oil. It has been shifting always very smoothly (with some kicks directly after the oil change when shifting from N to D.

[tredy]

Hi Marsalek!

Our cars have the EXACT SAME behaviour as you described! Also mine changes gears very smoothly, I'd say the transmission is great but I'd really like to find an explanation (or a solution if there is) for this issue! It would be helpful if you add the specific model and year of your C5 in your profile!

maybe we can investigate this issue further

[marsalek]

Hi Tredy,

I think it is normal behaviour and there are only a few of us who observe it so closely. If this were a fault (flaring), it wouldn´t probably manifest completely the same way on our both cars.

All the best!
Karel

[GiveMeABreak]

Unless any of you guys have read the gearbox ECU with Diagbox and can report fault codes, it may just be down to the adaptive learning of the system. If any of you have disconnected the battery without following disconnect / reconnect procedure (BSI Reset / Battery Disconnect / Reconnect Procedure), then there is the possibility that stored data will be lost.

[tredy]

Great guide mark! but what if the battery is in the trunk? obviously you can't close it...so what's would the procedure be in that case? (3.0 HDi has the battery in the trunk)