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Stu
Member Since: 08 Feb 2009
Location: Hampshire
Posts: 2423
  
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| Revs fluctuate when accelerating (and now terrible noise!) |
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Hi,
Wondering if you guys can shed any light on a couple of issue.
1 When I start up from cold, the engine starts but when the revs drop it stalls. If I rev to about 2000 revs for 30 secs all is well.
2 When I accelerate moderately the revs increase, then drop back, then go up again and drop back again speed does increase but it's not smooth and there is a slight vibration.
I don't know if the two might be linked. It has just been serviced and just had a new turbo fitted if that might have anything to do with it.
Thanks in advance D3 HSE MY05 Auto
Expo Rack, Club MTR, LR Spots, A Bar, Light Guards, GNVP Sump Guard, GNVP Ladder, Cup Holders, RLD A Bar brackets. Disco3Club stickers, Aux power on Mod
Last edited by Stu on 9th Mar 2009 6:09 pm. Edited 1 time in total
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 1st Mar 2009 12:53 am |
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Gareth
Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26702
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I have not got (1), but I do have (2)
Currently under investigation on my car. If you open your window whilst the revs are fluctuating, do you hear a faint Whooshing sound coming and going in time with the rev fluctuations?
I have not had a new turbo, and mine has had these fluctuations for ages, but its got much worse recently. I had some juddering, but since the 120000 service they have gone. 10forcash reset the adaptive memory in my gearbox and that seems to make the judders disappear.
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| 1st Mar 2009 1:12 am |
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Stu
Member Since: 08 Feb 2009
Location: Hampshire
Posts: 2423
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So did getting the geabox reset solve the problem for good or has it come back? Mine feels as though the car is reading that there is too much fuel going in and is reducing the revs then it instantly says the gas pedal is down put more fuel in, and then whole process repeats. To me it feels like a sensor is giving a faulty reading, or that the ecu needs a reset. I don't know how the memory in the gear box workout I would like to know if that sorted it for your good.
thanks D3 HSE MY05 Auto
Expo Rack, Club MTR, LR Spots, A Bar, Light Guards, GNVP Sump Guard, GNVP Ladder, Cup Holders, RLD A Bar brackets. Disco3Club stickers, Aux power on Mod
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| 1st Mar 2009 10:55 am |
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Gareth
Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26702
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The reset of the memory did not completely eliminate it, but it did improve it for about 200 miles. Then the adaptive memory learned my driving style and the fluctuation came back.
There has been quite a lot of chatter on here recently about juddering and surging (the proper term for the revs rising and falling under load)
Some have said that a transmission double flush is the answer, but due to the high cost of the oil, and the fact that most of it goes to waste means nobody has had it done yet.
I agree with your sensor theory, it would be interesting to know if you get the audible whooshing sound in time with the surge?
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| 1st Mar 2009 12:09 pm |
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AndrewW
Member Since: 06 Aug 2007
Location: Saddleworth
Posts: 2302
 
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Does anyone know the algorithm(s) for the adaptive gearbox control? (As if I could understand them if I was told  ).
I wonder because my driving style varies with a psychotic level of variety, from a short shopping trip to a solo joy-ride, from gently with a cold engine to wild with loud music, from rapid on a smooth surface to s-l-o-w-l-y over the rough stuff and always moderated by the vehicle content (SWMBO, grandchildren, nothing, delicate furniture, mate to impress  ). How does my gearbox adapt to that?
A
Edit - perhaps we need a switchable re-map for the gearbox - with Meldrew and McQueen positions on the switch. 2006 D3 finally swapped for a 2016 D4 Graphite in Graphite grey. No mods
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| 1st Mar 2009 1:31 pm |
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Stu
Member Since: 08 Feb 2009
Location: Hampshire
Posts: 2423
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I think that's a valid point, I drive the car and so does my wife, we are bound to have different driving styles so how does it adapt. I have only had the car for about 4 days, so I will see what the dealer says. Although I am slightly concerned that they are in Manchester and I am near Portsmouth! D3 HSE MY05 Auto
Expo Rack, Club MTR, LR Spots, A Bar, Light Guards, GNVP Sump Guard, GNVP Ladder, Cup Holders, RLD A Bar brackets. Disco3Club stickers, Aux power on Mod
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| 1st Mar 2009 10:20 pm |
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Gareth
Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26702
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I am the only driver of mine. The surge is much worse when towing a caravan, but still there when solo.
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| 1st Mar 2009 10:22 pm |
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Stu
Member Since: 08 Feb 2009
Location: Hampshire
Posts: 2423
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Mine is pretty mild and seems to drop about 500 revs before picking up again, but I just want to get it sorted before it leads to something worse. Does anyone know if this affects certain age or mileage engines? Mine is a 05 with 90,000 on the clock D3 HSE MY05 Auto
Expo Rack, Club MTR, LR Spots, A Bar, Light Guards, GNVP Sump Guard, GNVP Ladder, Cup Holders, RLD A Bar brackets. Disco3Club stickers, Aux power on Mod
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| 1st Mar 2009 10:27 pm |
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Gareth
Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26702
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54 plate with 120000 on the clock here.
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| 1st Mar 2009 10:28 pm |
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Gareth
Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26702
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HERE is a link to a video I recorded whilst driving my D3, towing the caravan.
Its quite long, and shows the instruments. Watch the tachometer, especially when the speed is constant at about 50mph. You can quite clearly see the needle bouncing in 1 second cycles.
Oh by the way, the police sirens are not real, the kids were watching Spiderman in the back, and the road noise is the STT's.
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| 2nd Mar 2009 9:38 am |
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Stu
Member Since: 08 Feb 2009
Location: Hampshire
Posts: 2423
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Hi,
Mine is identical to that, seems to be at about the same speeds as well. I'm doing a couple of hundred miles today, so I'll try and see if it does it at any other speeds etc. I'll also try listening for the wooshing noise as well.
Thanks for the feedback. D3 HSE MY05 Auto
Expo Rack, Club MTR, LR Spots, A Bar, Light Guards, GNVP Sump Guard, GNVP Ladder, Cup Holders, RLD A Bar brackets. Disco3Club stickers, Aux power on Mod
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| 2nd Mar 2009 11:03 am |
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stapldm
Member Since: 11 Sep 2006
Location: Swine Town
Posts: 2330
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Gareth wrote:HERE is a link to a video I recorded whilst driving my D3, towing the caravan.
Gareth/Stu; does that surge still happen when using cruise control? I'm just wondering about excluding the accelerator pedal angle sensor from the mix.
It does look odd; it's like the auto box is undecided as to whether or not it should go into full lock-up. Does this effect stop when driving in command shift? Dr. Ian Malcolm:
"Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should."
Transgenic tomato anyone?
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| 2nd Mar 2009 12:21 pm |
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Gareth
Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26702
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The same thing happens with cruise control. In fact, if you were (on a clear road of course) to engage CC at 30 mph, then hold down the + button. The car accelerates in the same way, with the revs climbing through each gear an a series of 1 second surges.
In command shift, it will still do it. In CS because you can apply much more power without the gearbox changing down, the fluctations will be even greater.
If you hold it in a lower gear using command shift, i.e more revs, and less accelerator application to maintain a speed, then the surge goes away.
It definitly seems to be a load dependant phenomenon.
I am waiting to meet up with TFC in the near future so we can hook up the Autologic diagnostics and go for a drive to see if we can get some real time data.
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| 2nd Mar 2009 1:14 pm |
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stapldm
Member Since: 11 Sep 2006
Location: Swine Town
Posts: 2330
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I'm surprised it still happens in command shift; my (admittedly not brilliant) understanding of our gearbox is that under stable load/speed conditions it locks the torque converter to reduce power losses, and does this in every gear using electronic feedback to determine when to unlock/change gear/re-lock.
When it does this, you cannot see the RPM change when you flex the throttle; or at least that's true in my MY2007. It takes some further event (kick down, engine labouring, high/low rpm etc) for a signal to be sent to the gearbox to unlock and start monitoring torque again.
It seems to me that you may never be making it into lock-up at all, or at least constantly approaching lockup and backing off. I'll look forwards to hearing what 10 has to say (it's always a learning experience for me when he's involved  ) If the 'box is attempting this and failing every second I'd be upset if a code wasn't being stored.
You say that higher revs and less power make the feature go away, but remember at higher revs you're also pumping more auto fluid through the box too, so a minor restriction in one of the oil ways or a slightly under-performing pump, or a thermostat that's only opening halfway would make less of an impact.
Finally I know that in some cars the lock-up is withheld until the oil is warm; and this is achieved by a mechanical thermostat (some cars also prevent top gear selection in this case). Perhaps if the D3 'box has this feature you may have a partially failed thermostat.
Sorry, that's me struggling at and beyond the end of my technical tether, but I don't suppose you've had the chance to check the auto fluid level (in that sealed for life of the warranty unit)? I know that low steering fluid causes pulses in power steering effectiveness; can low auto fluid do the same to an auto box? Dr. Ian Malcolm:
"Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should."
Transgenic tomato anyone?
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| 2nd Mar 2009 3:21 pm |
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Gareth
Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26702
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When TFC did the 120k service a few weeks back, he drank drained a sample. We wanted to check it was a) the right oil, and b) was not burn't.
The conclusion was it was the correct oil (not red in colour) and it smelt like oil.
We then went for a short drive with the computer plugged in, but nothing was conclusive.
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| 2nd Mar 2009 3:45 pm |
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