Viano 3.0 CDi Limited initial RPM in drive and reverse

Discussion in 'Engine' started by GWhittell, Sep 4, 2017.

  1. GWhittell

    GWhittell Member

    Messages:
    49
    Joined:
    May 23, 2015
    Location:
    Wakefield, West Yorkshire
    Car:
    Viano 3.0 Cdi
    Hi,

    I've been reading many posts regarding gearbox issues and the various limp modes but I can't find anything that has helped me get closer to identifying what the issue may be. My gut feeling is that the gearbox is the issue.

    If anyone can offer any advice before I take it to a transmission specialist that would be much appreciated. If you need any further details or tests performing just let me know.

    Cheers!

    Car :- 2007 Viano 3.0 Cdi (204 bhp) with the 722.6 gearbox, ~140k miles. Owned to about 2 years.
    Having just got the old service history it's not had the ATF done since 20k miles (very early?) so it's done about 120k on the old ATF fluid :fail

    Symptoms:- When selecting drive or reverse the car won't rev above about 1000 rpm if the car is on an incline it just sits ~1000 rpm and emits a small amount of black smoke from the exhaust. Once (if) the car starts move once the revs build the turbo kicks in and it drives ok. If the car is on the flat it's just sluggish to move off until the revs build.

    Once rolling the car is still a bit unresponsive but does shift up and down as I would expect and kick downs do occur but with less acceleration then I'm used to. If it's floored the boost does on occasion hit 1.5 bar but usually its around 1.3 bar (floored) and about .5 bar when cruising @ 60 mph.

    The fuel economy around town has dropped to about 20mpg whereas it's usually ~ 25-27. On the motorway cruising on level ground @60 mph it will currently average ~33 mpg which is about usual but drops very quickly once dropping town driving. Combined driving used to give about 28 - 30 mpg.


    What's been done so far:-

    Star diagnostic at a local indy who reported that there were no faults related to the drive train (but many others for AC, parking sensors etc.)

    This weekend I have changed the ATF fluid (it was tar black) and flushed the oil cooler and torque converter using 11 litres of fluid in total. I also swapped the electrical connector housing but oil hadn't got past the 'O' rings on the old one. I wouldn't say the oil is now cherry red,I would have hoped that 11 litres would definitely make a bigger difference.

    I have removed the DPF and I could see through it once I tapped the top of the pipe as the ash/soot fell out. I blasted it with compressed air just to be sure which cleared most of the channels that I could see.

    Tests performed (any readings were taken with ODB reader Torque pro on an Android mobile with a Bluetooth ELM 327 :-

    When selecting drive/reverse, engine load goes from ~20% to ~75%. Car starts to move with much greater force than previous, (if on the handbrake the back end really sits down)

    If I remove the connection to the MAF on idle the turbo winds down until reconnected. I have swapped the MAF for a genuine Bosh part which didn't help.

    On the road the car will upshift very early to climb a hill which is unusual. On the flat it drives a little less responsive then usual but it will now always upshift whenever I press the accelerator whereas it will usually take quite a bit of movement before the gearbox kicked down. With it being the 3.0 it usually does most things on the move in 5th (unless towing 1.6 tonnes).
     
    Last edited: Sep 4, 2017

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