Robos4

Hi All,

2008 PDK Carrera 4 (16k miles on clock )

I'm trying to fix a very audible vibration rattle. Best way to describe it is when your are in drive, AC on and at lights or in a car park you remove foot off brake pedal and the car naturally rolls forward, at this very initial point the car has a bad vibration like the idle rpm can't handle the load and whole car vibrates (like a dud dud dud dud very quickly).

Standing next to the car as I go forward and back (dows it in reverse also) it sound slike it's coming from the rear wheel area (most likely exhaust).

Is this an easy fix like just bumping the idle up a bit when AC is on (is that possible)?

Worth noting this is not just my car, I have a friend who bought same model car as me and he mentioned the exact same thing happened to him and the 3 of the other Carerra's he test drove when buying.

I have since changed engine mounts and PDK gearbox mount. It is slightly better but till there.

If I turn AC off it won't do the vibration (but where I live we need AC) also funny if I put it in sport plus mode, it won't do it also..

Thanks in advance.

Rob

Fahrer

You indicate that the car is a 2008 but it also has a PDK trans. From what I understand, PDKs appeared in 2009 and later cars. If the car does have a PDK and you take your foot off the brake, the clutch begins to engage but is still slipping. Perhaps the clutch (wet type) needs servicing or a fluid change? That seems odd though with only 16K miles.

Robos4

Thank you,

They built the first 997.2 in 2008 and was ready for registering early 2009. It’s a 997.2 100% haha PDK, direct injection etc.

I have it booked to change the fluids for all diffs and GB/clutch.

Don’t think it would be the reason but will have to wait and see I guess.

Ironman88

If your car was built in '08, and it's a 997.2, then it's an '09 model year car.

Same thing with my car. Built in Nov '08, but it's an '09.

Fahrer

Bye the way ( I know, a different car) I have a 2019 VW Golf Alltrack with a 6 speed dual clutch trans. VW specifies 40K miles for the DSG fluid change but a fluid change every three years for the Haldex unit which also has a wet clutch, regardless of miles. Perhaps age can be a factor as well. Newer VWs with a 7 speed DSG need fluid changed every 80K miles as I understand the clutch and trans have separate fluid systems.

BucketList

Your PDK oil is 12 years old. Way overdue based on time. Fluids have 2 clocks, one is mileage and the other is time. Both the PDK oil and the diff oil are due.

Wayne Smith

My 2010 was built in July of 2009. It was delivered to a dealer in Hawaii in September 2009 ... Complete with heated steering wheel. It was sold in California in November 2009. Nonetheless it is a 2010.

There have been software changes to soften the PDK over the years. These updates have been non reversible. Some dealers don't like doing the update because if anything goes wrong in the middle of the process the PDK can become bricked. And the more passive response may leave the owner non plussed.

I like the way my 2010 performs and have told the dealer each time I have had my PDK serviced to NOT do the update. But it may be that on the very early units the update would be beneficial. Defining beneficial is personal of course.

Also, remember this is a manual transmission without the third pedal. When you release the brake you tell the computer to start engaging the clutch. Without throttle if you did this with a third pedal you would expect a (negative) response from the car. Without a torque converter that's just the way it is. Without being there I can't tell exactly what you are experiencing. The fact that you report this behavior on more than one car makes me believe what you are seeing is normal.

Fullyield

Have your rpm at operating temperature increased by 100.

sharkster

The 2009 early cars here in the USA (and yours most likely) have the idle speed even lower which causes it to do that indeed. You can see if there's any update available from the dealer (the later cars seem to idle a tiny bit higher). You can also adjust that with a tune although you shouldn't have to of course. We find if the idle speed is raised by 50pms that the vibration is totally gone.

Robos4

Thank you sir, exactly what I was looking for. I always thought it was rpm related and mine does idle very very low, like 650rpm which I remember saying to myself is too low.

I will look further into this and report back

Thanks all

Wayne Smith

Great information that I wasn't aware of. Thanks for the lesson.

sharkster

No worries at all and I know it's annoying indeed. That's why in the sport and sport plus modes with more aggressive throttle mapping (and AC switched) it gets lessened.

No worries. If any of you already have some kind of perf software you could ask your tuner to bump the idle speed by 60rpms and that'll fix it- just make sure though that you have a stock file as well and it's not raised too much ouf of the normal zones for drive cycle checks.