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!Update! - Idle problem

DeZZar

VR32W
Location
Melbourne, VIC
Car(s)
08 5DR R32 DSG
said Id keep you guys informed on this so heres an update.

car went back to the dealership on Thursday for them to have another go at determining the cause of our problem.

The problem: (for the benefit of anyone that might have the same thing happen)
- after driving for some time the car would pick up revs to 1,000 or more whilst idle and stay there for a while, then drop back to only 8-850rpm. Never 600 like normal.
- this wouldn't happen everytime. but often enough to raise an alarm
- when the idle played up so did the dsg. you could feel the clutches slipping when attempting to take off rapidly, and you could feel the changes occuring like a normal automatic.


So the service department ran some tests and could not come up with any fault codes. They started tracing the electrical system and discovered that the earth grounding the battery was very very loose. (odd given I've never even seen the battery).

They think that what was happening was that the earth leakage was causing a voltage drop which the engine was attempting to compensate for. This then cofused the changing patterns for the dsg.

I am still a little dubious about how this could affect the dsg performance - it certainly doesn't seem to make any sense from how they described it.

Anyway - I've been for a few quick drives since and the car has behaved itself. So this may end up beging the answer.

So if anyone has and idle racing issues - check your battery!! :iono:
 

mrx

Connoisseur
Location
Perth, Australia
Car(s)
2007 CW Golf GTI 5dr
Yes, a loose battery terminal will cause erratic idling, I've seen it on older cars, but didn't think to mention it - I thought the golf would have had enough smarts to log some sort of fault for that.
 

just_quietly

Power Banned
Location
Sydney AUS
Car(s)
Mk5 Golf GTI 07 spec
Yes, a loose battery terminal will cause erratic idling, I've seen it on older cars, but didn't think to mention it - I thought the golf would have had enough smarts to log some sort of fault for that.

Obviously not...go the 6spd! haha jks DSG is good but not for me!
 

DeZZar

VR32W
Location
Melbourne, VIC
Car(s)
08 5DR R32 DSG
yeah the increase idle for a loose battery makes sense to me.....its the bit where this in turns plays havoc with the dsg that I'm confused about.

and the fact that the car didn't log a low voltage code or something is definitely odd.....

anyway....guess we'll see if its truly fixed after this weekend
 

jaush

Aus Liebe zum Automobil
Location
Melbourne, Australia
Car(s)
R32
Well... The DSG has it's own control unit (needs power) and the gear changes are electronically actuated as far as I'm aware, so I can see inconsistent power supply could fuck around with it.

Fingers crossed that's all it was!
 

Jester_Fu

My Name is Angela.
Location
Swidneh
Car(s)
Daytona Grey TT RS
Yeah, all sounds plausible to me too. The fault might not have been logged because there is a certain tolerance for low voltage before it logs. I'd suggest it's around 11Volts or so. When the car is running, the alternator will throw around 14Volts toward the battery. It's possible the system detected a drop in voltage at idle and sped the engine up to charge it, but the bad earth then disappeared (so to speak) and the idle dropped as it was now reading a better voltage.

I agree that with the DSG being electronically controlled, it's possible the apparent voltage drop confused the controller or ir slipped the clutches trying to keep power in the engine and alternator to keep the voltage higher.

All very plausible - but only time will tell if they've fixed it now. Best of luck - you'll have to give them a couple of beers if they fix it... earth faults are generally a prick to find so the fact they even checked the battery shows they give a shit :thumbup:
 

DeZZar

VR32W
Location
Melbourne, VIC
Car(s)
08 5DR R32 DSG
hi AKGT!

I took the car to Burwin Volkswagen. Here are their details.

Address: 700 Burwood Highway, Ferntree Gully VIC 3156
Phone (03) 9752 2844
Fax (03) 9752 3873

Hours Mon - Sat: 8:30 am - 6:00pm
Sun: CLOSED

this is my only experience with them. Weren't much help the first time round but they seem to have correctly identified the problem this time and I haven't had any issues since.

Hope its the same simple fix for yours. Let us know how you go!
 

Jig

Flow Motion
Location
Australia
Great Update Dezzar. I would say that's a good troubleshooting know-how right there. I wonder how many VW dealerships would head down the same logic of finding where the issue lay.
 

AKGT

New member
Location
Melbourne
Car(s)
Golf V GT DSG
I will check under the bonnet tonight.

If I can't find anything obvious I'll take it to the dealer.

Thanks
 

AKGT

New member
Location
Melbourne
Car(s)
Golf V GT DSG
Checked under the bonnet - no loose wires on the battery or the grounding cable.

It looks like I need to book it in.
 

AKGT

New member
Location
Melbourne
Car(s)
Golf V GT DSG
Took the car to St Yarra VW in Richmond.

They found two faults:
Supercharger clutch no opening (only happend twice) - only needed a software update;
Turbocharger overspead - can't clear the fault - they think it may be something to do with my AWE catback exhaust - bullshit if you ask me.

The idle speed is still arround 1000rpm - they not going to work on it until I put the standard exhaust on it.

I'll do it, but as far as I'm concerned it is a waste of time. The idle problem was there for arround 3 months. The exhaust was on the car for less than two weeks. :mad0259:

Is anyone else experiencing high idle speed.
 
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