2008 3 series Automatic traction problem.

[OllyP2000]

Hello! Ive recently come across a problem with the automatic gearbox on my 2008 325D. If I come out of a junction in the wet from a standstill and accelerate enough to lose traction, the car will kickdown into 1st gear from 2nd gear and sit on the rev limiter for a good few seconds before it changes up gears again. This can be dangerous if trying to accelerate out of a junction and your car wont let you properly accelerate and I just sit there waiting for the car to sort itself out. Anyone had a similar problem or any Ideas to what the problem may be? Im guessing either gearbox software or traction control module could be the culprit. TIA

[Greydog]

Morning Olly

Welcome to the Forum

Normally if there was an issue it would throw a light, a diagnostic check will tell you if there is an issue or not as fault codes are stored even if not present.That will help avoid throwing money at something not there. There are garages out there happy to take your money for all sorts of "problems"

From your description you are clearly enjoy the cars grunt !! Just remember your 325d produces about the same amount of torque as an E46 M3 if it has been ECU tuned possibly quite a bit more. So I would check the rear tyres are they a reasonable make and do they have plenty of tread are the pressures right, it doesn't take much to tear them up (8 to 10k with my AMG's). You could reduce right boot pressure in the wet as due to the long dry spell the country has had junctions and roundabouts are always particularly slippery when it eventually rains. Or use the manual function and pull off in 2nd, On slippery muddy surfaces when towing the horse trailer I select 3rd in manual and let the torque do the work.

Dave

 

[OllyP2000]

Thanks for the reply Dave!
Maybe that is just the case heavy right foot syndrome haha, I scanned the car for codes with a snapon tool and there are no transmission codes present or speed sensor codes so maybe it is just the nature of having an open diff and the one wheel wants to spin up really fast causing the car to rev up quickly when I lose grip. 
I have continental run flats on the rear and the pressures are correct, however the tread is nearing the low tread indicator so it might be time for some new boots soon!  Any runflats you would recommend in particular?

[Greydog]

Hi Olly

The torque the 325d 330d and 335d produce is mega and wont help as when your pulling away your in the meat of the torque band straight away. The E90 M3 has 420bhp and 400nm torque which doesn't peak until 5k + While your 325d in standard trim has around 200bhp and matches the M3's 400nm torque but yours is available from 1300rpm !! with a tuned ECU you will see around 450nm. The 330d has 520nm and 335d 580nm standard so with a bit of help are monsters. Real tyre munchers all 3 of them particularly with an open diff 😈

If your near the wear indicators that wouldn't help either, Continental Run Flats were among the OEM suppliers I believe as were Bridgestone and Michelin 

Enjoy, just wear your ballet shoes if it rains 🤣

Dave