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Discussion Starter · #1 ·
I have a 2014 Q3 SE TDI Quattro, its Diesel automatic and its been a really reliable car for 4 years. I recently took it on a holiday to cornwall and drove on some uneven surfaces.
Since coming back in the last 2 days I've noticed a shudder when accelerating from about 30 to 40mph - but sometimes at lower speeds as well 10-20mph. Its happened maybe 3-4 times in total.
Generally its happened when I'm accelerating up a hill.
The first time, I just lowered the speed and then accelerated again, given the pedal a good hard push (I'm usually very light on the pedal), the car when back to functioning as normal. I thought maybe I was being too light on the accelerator.
The second time, I just pressed the accelerator hard, but it caused the car to shudder more, and it was only after slowing down to about 20mph and then gently speeding up again did the car go back to normal.
The third time, I was doing a hill start, and the car shuddered as I went from around 5mph to 10mph.

The only way I can describe the sensation is that, It feels like a manual car when youre in a high gear and you're trying to climb a hill, but I've never had this problem with my automatic.

I took the car to the garage and the mechanic drove around in it for about 10 minutes, he definitely put the accelerator and the brakes on hard and the car behaved as normal. I was so frustrated. The mechanic has no idea what was wrong, and basically just said its behaving as normal. He checked the engine oil level but didn't check the transmission fluid level. He then said I should just get a full service and change all the filters. I'm not sure what to make of this advice - I'm not due a service until August, and I wanted to do one with my MOT.

If anyone has had a similar problem or thinks they know what might be wrong, I would be really grateful to hear your thoughts.
 

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Discussion Starter · #2 ·
Just to say my car has done 69000 miles
No engine or warning lights on (that would actually be helpful)
Engine sounds the same even when it has the shudders
No leaks that I can see
 

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When it shudders, what revs is the engine doing? Is it changing down a gear or two, or just staying in a too higher gear which is causing the shudder?
 

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Discussion Starter · #4 ·
When it shudders its usually doing about 1300 to 2000 rpms I believe. The red needle is some where between 1 and 2.

The gears don't change. First time I got the shudder I was on an A road accerlating from 30 to 40 mph on D5. Gear didn't change, had to really push the accelerator, then gear change to D6 after shuddering stopped. The second time it happened I approached the hill on D6 at 40mph. I accelerated to get to 45mph and the car shuddered but the car was in D6. I had to decelerate to 30mph and the gear shifted to D5 and then accelerate again gently.
 

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Did the shuddering start after you filled up with fuel? Have you ever had the fuel filter changed? Are you a 'light' driver?
 

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Discussion Starter · #6 ·
Did the shuddering start after you filled up with fuel? Have you ever had the fuel filter changed? Are you a 'light' driver?
I filled the tank up several days ago, and I'm currently on half a tank. Just after fuelling up everything was fine. I've never had the fuel filter changed as far as I know, its not normally something they do in a service I don't think.

I'm not sure what classifies as a light driver but generally I never press hard on the accelerator, I drive more carefully than my grandma. I do a lot of miles in my car and have quite long journeys to commute. I drove about 600 miles in the last week for the Cornwall holiday.
 

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So, until you filled up a few days ago everything was okay. What filling station did you fill up at? I am just trying to isolate the problem.
 

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Discussion Starter · #8 ·
So, until you filled up a few days ago everything was okay. What filling station did you fill up at? I am just trying to isolate the problem.
I filled up at a sainsbury petrol station near torquay, definitely put diesel in my tank.
I managed the 200 mile drive back from torquay after filling up with no problems. Left my car alone for a day and then yesterday it starts shuddering
 

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I wonder if there is some water or other contaminant in the fuel. If you filled up when the tank was really empty it is possible that some crud in the tank could have been disturbed. As you are getting no warning lights I would suspect the fuel. What I would do is to go to a Shell, BP or main filling station, fill up then go for a drive. I would wait for any other input but I can't see it being an electrical or mechanical problem.
 

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Discussion Starter · #10 ·
I wonder if there is some water or other contaminant in the fuel. If you filled up when the tank was really empty it is possible that some crud in the tank could have been disturbed. As you are getting no warning lights I would suspect the fuel. What I would do is to go to a Shell, BP or main filling station, fill up then go for a drive. I would wait for any other input but I can't see it being an electrical or mechanical problem.
I never thought of that, but I will fill up again and go for a drive. I suppose if there was a problem with the gear box or transmission fluid the problem would be more consistent and getting worse
 

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I rather like the fuel problem idea.
If it was only since that tank of fuel, it has to be a good suspect.
My TVR had to have super unleaded and anything was fine except Tesco’s which made it sound and run dreadful but, at 18mpg, you had to fill up where you could.
 

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Discussion Starter · #12 ·
Hey guys
So I sent my car in to a garage I trust and they ran a full diagnosis. Turns out they couldn't find anything wrong with the gearbox engine etc.
Their best advice was the same as yours use up the current fuel and refill with premium diesel from shell or vpower.
They also incidently found a fault with haldex clutch which engages 4 wheel drive but apparently it doesn't cause the diesel knocking that I've been experiencing.
 

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Well that's something I guess.

Haldex failures are not unknown and can usually be prevented removing the pump and cleaning the pump filter gauze and refilling with clean oil - prudence suggests every 20,000 miles. The official Audi service recommendation doesn't include the pump removal part - just the oil change.
 

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Discussion Starter · #14 ·
Well that's something I guess.

Haldex failures are not unknown and can usually be prevented removing the pump and cleaning the pump filter gauze and refilling with clean oil - prudence suggests every 20,000 miles. The official Audi service recommendation doesn't include the pump removal part - just the oil change.
Thanks that really useful - will ask my mechanic is he can clean the pump filter gauze and change the oil.

I've filled up on V-power premimum diesel and the car feels like its returning to normal. A few times the engine sounds louder than before particularly at lower speeds when accelerating but no more engine knock, and much more power on the accelerator.

I was just wondering - does anyone else with an automatic diesel Q3 find that in low gears the gearbox changes gears a bit later, so the rpm go up to 2000-2500 before the gears shift from D1 to D2, D2 to D3. This high rev doesn't occur from D3 upwards, the transitions are more smooth.
I genuinely never paid much attention to this before I had the issue with engine knocking. Now I'm not sure whether this is normal for a diesel automatic or there's some residual problems with the car.
 

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The DSG characteristics can be changed by the 'Drive Select'. However, the DSG does learn from your driving characteristics. What you are experiencing in the lower gears could be to do with the high torque from the diesel engine.
 
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