Thread: 2011 D4 'Gearbox Fault' warning

Originally Posted by Bananas

So I consulted Dr Google and low fluid level was listed as a possible cause to this fault (makes sense) so I cleared adaptions but still got the fault then continued with the top up. Close to full fluid at 35 deg c - no fault! Slips nicely into reverse and drive.

Not quite counting my chickens yet.....

40C is correct a slight trickle should come out with engine running

It's too early for the thanks to everyone for their helpful comments - but so far, so good. Maiden voyage was a success. Gear changes are so smooth up and down, most are impossible to notice without the iiD displaying the gears. There's still a bit of taco needle bounce in 4th, which of course could be something else, but I'm hoping this will reduce over the next week or so.

Got an hour trip tomorrow through suburbia and highway to give it a proper test.

Xmas day trip yesterday has left me with mixed impressions of success or otherwise.

The 45 min trip to lunch mainly on semi rural backroads with lots of hills and corners and straights up to 100 km/h was a dream. I took the highway on the way back and had a fair bit of surging happening when accelerating at speed or applying more throttle to maintain 100 km up a steady incline.

Perhaps ‘surging’ is not the correct term. It felt like a series of power drops about 0.5 seconds apart like a petrol engine that needs a tune miss firing.

Gear changes were beautifully smooth and the surging would stop as soon as I backed off the accelerator or was at a constant speed on flat even road. The surging did not happen accelerating from a standstill. While it was happening when accelerating at speed, it would also stop if I put my foot down. Shifting from D to S would also reduce it but not stop it entirely.

This vid posted by Lukeis in 2020 shows a similar tacho behaviour: https://youtu.be/oUZvSLtWW6s

I have a new set of injectors and a new leak off line to put in sometime in the next week and will clean the MAF sensor and throttle body and go searching or obvious leaks so I’m hoping this is an injector issue. The injectors are still original at about 360k and I was experiencing this behaviour prior to the valve body overhaul.

Dr Google seems to attribute this type of behaviour to just about anything from a dirty air filter to total transmission doom so I’m not entirely confident I’m on the right track.

While I have my head under the bonnet is there anything else I should take a look at?

Hope you’re all having a great Xmas.

More likely a failing torque converter with the tacho bounce.

Originally Posted by loanrangie

More likely a failing torque converter with the tacho bounce.

Yeah I came to say the same thing. Common for the TC to fail on this model and cause flaring like this.

And the zip kit won’t fix a bad TC

Thanks guys.

Not the news I was hoping for but not a surprise. I’ve known the TCs days are limited for a while now. Hopefully it’ll hang in there till I can line up a replacement. Seems like it’s on the outer edge of my DIY abilities.

Originally Posted by Bananas

Thanks guys.

Not the news I was hoping for but not a surprise. I’ve known the TCs days are limited for a while now. Hopefully it’ll hang in there till I can line up a replacement. Seems like it’s on the outer edge of my DIY abilities.

If you put it in Drive and bring the revs up while keeping left foot on the brake, a faulty TC will slip and cause rpm fluctuations. How was the TF when you drained it? Mine was kinda greenish, but I had no TC issues at 220000km.

The TC itself is not dear to fix by a reputable transmission shop, it's the clamping clutch ring inside that gets worn and slips and causes the surging. A new genuine TC is over 2k, which is not too bad considering what they do. The issue is getting access, as the entire transmission has to come out.