C4 grand picasso 2 litre diesel auto poor aceleration

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

derbyshire1970
Posts: 27
Joined: 31 Dec 2019, 12:05

C4 grand picasso 2 litre diesel auto poor aceleration

Post by derbyshire1970 »

C4 Grand picasso has poor acceleration on kickdown jumpy when changing gear gear box isnt slipping
this is the full auto gear box and not the egs version
Comments or thoughts please

User avatar
GiveMeABreak
Forum Admin Team
Posts: 21577
Joined: 15 Sep 2015, 19:38
x 2163

Re: C4 grand picasso 2 litre diesel auto poor aceleration

Post by GiveMeABreak »

I can't remember if you have Diagbox, but getting it hooked up and diagnosed is really going to be a must to be honest.

Most AM6 gearbox issue will have an associated fault code and seeing as there are over 120 possible fault codes you can see why it is important to get a diagnostic on it.

Are you having any gearbox warning faults?
Have you changed the Gearbox oil and if so how many changes has it had (bearing in mind you can only change 3 litres in one change as the other 4 litres can't be emptied from the torque converter). So it really needs at least 3 changes over a month or so to get as near to a full change as poss. And I'm also assuming the oil counter was reset after each change?

If you have and codes, list them up here and I can see if there are any specific issues.

It might also be worth checking with your dealer to see if there has been a gearbox ECU software update.

derbyshire1970
Posts: 27
Joined: 31 Dec 2019, 12:05

Re: C4 grand picasso 2 litre diesel auto poor aceleration

Post by derbyshire1970 »

i dont have a diag box
the ATF has been changed once a few weeks ago ( it hasnt had the 2-3 changes as per previous dialogue )
It isnt coming up with any faults on the dash board , it is going in next week for a new CV boot so i will get a second oil change done then as well
i will ask about the oil counter
The garage are going to link it up to a diagnostic box to see if it brings anything up
keep you all posted
Thanks for the response

User avatar
GiveMeABreak
Forum Admin Team
Posts: 21577
Joined: 15 Sep 2015, 19:38
x 2163

Re: C4 grand picasso 2 litre diesel auto poor aceleration

Post by GiveMeABreak »

Make sure you get any and all fault codes when you do.
Absolutely essential that the oil counter is reset as this has a direct impact on the operation of the gearbox. The ECU accounts for oil deterioration over time and adjusts its operation accordingly.

Only the dealer will be able to see if there is a newer software update for the ECU, so bear that in mind.

Let us know the outcome.

derbyshire1970
Posts: 27
Joined: 31 Dec 2019, 12:05

Re: C4 grand picasso 2 litre diesel auto poor aceleration

Post by derbyshire1970 »

Citroen Mansfield want £89 just to plug in a laptop to tell me if there is a software update

User avatar
GiveMeABreak
Forum Admin Team
Posts: 21577
Joined: 15 Sep 2015, 19:38
x 2163

Re: C4 grand picasso 2 litre diesel auto poor aceleration

Post by GiveMeABreak »

Yes unfortunately that't the standard charge for connecting up their diagnostic Kit (Diagbox) - but the difference being they have direct access to the PSA servers that can query the ECU, check the database as to whether an ECU update is available and applicable to your specific engine.

Other non-franchised garages won't have access to this data, which is why the dealers charge as they do for this (as they have higher staff training costs and have to pay PSA for the leasing of the diagnostic equipment and all that).