rough idle, 5-spd

[eli]

my A5 sometimes bounces around absurdly while idling at a stoplight.
seems like it does it more in warm weather.
a dose of powerservice white didn't seem to help.
no problems on the highway, all the power is there that's supposed to be.
sometimes i think i feel it idling rough while i putt along at 40 mph in 4th gear, or speed/gear resembling 40/4 .
i'll certainly mention it to the dealer at the next oil change in 8k miles, but I was actually thinking of driving this car cross-country on a west-coast tour first...

 

[GoFaster]

Lots of them do it. Mine, too. Search this forum for "rough idle". No known solution. We don't even really know for sure what the underlying cause is. I suspect an ECU programming issue.

 

[SootHappens]

Recently mine has started doing this off and on. 22k miles on the clock... I told the dealer I didn't spend 26 grand to have a shaking engine. their response: "it's not showing any error codes"

Hopefully someone narrows it down to something simple!

 

[MPGeez!]

This is a common condition that occurs when the car is warm. Mine does it too. Jeff Robertson (of RocketChip fame) thinks he can fix it. Here's my layman's explanation: one of the injectors is fueling differently than the other three. He showed me what was going on in one of the Vag-Com modules. Jeff calls it "lumpy idle." Give the accelerator pedal a little nudge and it will smooth out. I'll see if Jeff has the time to look at my car (in the near future) and I'll post the fix-assuming he conquers it.

I just put up with it as I don't have too much idling in my commute.

 

[fish_on]

This is a common condition that occurs when the car is warm. Mine does it too. Jeff Robertson (of RocketChip fame) thinks he can fix it. Here's my layman's explanation: one of the injectors is fueling differently than the other three. He showed me what was going on in one of the Vag-Com modules. Jeff calls it "lumpy idle." Give the accelerator pedal a little nudge and it will smooth out. I'll see if Jeff has the time to look at my car (in the near future) and I'll post the fix-assuming he conquers it.

I just put up with it as I don't have too much idling in my commute.

I noticed if I ran a little bio it would smooth out, and if I reved it up it would come back ok.

 

[SuperJ]

I have it too, occasionally.

If I get annoyed I turn the Air Conditioning on, that seems to cure it by increasing the load on the engine.

 

[R-Sixxer]

Perhaps it's just a dirty sparkplug.... haha
But seriously, could a dirty fuel filter play a part in this? Mines got the shakes too, and it's annoying to no end.

 

[06SpiceRedTDI]

I don't think it would be the fuel filter, mine has been doing this since new. I guess if there is no solution I will just have to add it to my Signature, the performance V8 guys pay extra for this kind of thing you know.

 

[eli]

Lumpy idle. Heh. I don't mind it too much although it sometimes seems a bit silly. My kids in the back seat comment on it. I'm used to the rough idle from GM V8s with performance-cams/tuning, so a lumpy-diesel idle isn't so bad.

I'm less concerned with the lumpy idle than I am about the possibility that the lumpy idle indicates a problem that will manifest in some worst-case way in the middle of nowhere on Route-66-kingman-barstow-sanbernadino. Or I-40.

 

[tdi06]

Mine does it too! It was back at the dealer for two days and refused to do it for them and of course showed no codes. They gave me the car back and told me to bring it back if it did it again. It has, but it just seems far easier to hit the AC button when it acts up than keep dragging it back to them. The injector theory may be a plausable explanation in my opinion.

 

[matthewgb]

same situation

I have the same situation...

Is it possible to change the engine speed at idle with a VAG-COM?
I asked at the dealership if they could raise the idle ~25rpm and they said it wouldn't help, but they don't understand the problem.

 

[2footbraker]

Just get RC 1+ or 2 and be done with it . No more sputter! Actually I don't know if this is true but I wouldn't be surprised if an RC tune eliminated it.

 

[fireice]

i have a 2005.5 and mine has been doing it since day one. it is not the fuel filter and it is not the fuel... fuel additives (stanadyne) does not fix it... turning on ac fixes it.

it almost feels like the car is running on 3 cylinders.

i would love to hear if somebody fixes it because sometimes it does shake pretty badly when stopped...

alex
few cars

 

[blue_jetta]

My girlfriend's Father recently bought a used 2005.5. His had rough idle and the clutch just didn't feel right when I drove it. Turned out to be a destroyed clutch/flywheel and both have been replaced under warranty.

So he get's the car back and it's as good as new...and then the fuel pump dies. Well that's another story anyway, but he is getting a new fuel pump now (also under warranty).

 

[GoFaster]

Just get RC 1+ or 2 and be done with it . No more sputter! Actually I don't know if this is true but I wouldn't be surprised if an RC tune eliminated it.

Chipping mine had no effect on the rough idle. The rough idle has not gotten worse over time. I consider mine to be a minor irritant, nothing more.

 

[AudiMatt]

My Mk5 has the rough idle as well. It is bad enough that it feels like a 3 cylinder, like one injector just stops working. It isn't quite as bad as the MK1 diesel I put urethane motor mounts in to but it is definitely annoying to my wife and seems absurd for what we payed for the car.

I am also worried that the injector will eventually get worse especially after the warranty is up. Also, the vibration must put extral load on the motor mounts causing them to wear out more quickly.

 

[40X40]

My Mk5 has the rough idle as well. It is bad enough that it feels like a 3 cylinder, like one injector just stops working. It isn't quite as bad as the MK1 diesel I put urethane motor mounts in to but it is definitely annoying to my wife and seems absurd for what we payed for the car.

I am also worried that the injector will eventually get worse especially after the warranty is up. Also, the vibration must put extral load on the motor mounts causing them to wear out more quickly.

So, what did your dealer say when you asked them to fix this 'absurd' problem? We could all benefit from an explanation.
I've had it happen 2 or 3 times in 27000 miles, it goes away in a few seconds.

Bill

 

[AudiMatt]

I haven't taken it in yet. We've put 26000 miles on ours in a year and it we get a rough idle quite frequently. I'm calling the dealer on Monday...

 

[SpiceItUpDarcy]

Rough Idle When Warm

My vehicle has a had several problems;
Miles Problem
500 Glow plug bridge meltdown (warranty)
20000 Dual Mass fly wheel replaced (warranty)
56000 EGR? valve flap replaced ($700+ out of pocket)
59000 EGR valve replaced (warranty)
59000 Dual Mass fly wheel replaced (warranty)
59000 master and slave cylinders replaced (warranty)
Fuel filter must be replaced every 10-15k otherwise engine hesitates while accelerating.
Car "tremors" when idling after long drive time. The car has done this since almost new and they can not figure out what it is. The car has been in 4 times for the same problem. Now they are going to try some "harmonizer" part and most likely will have to replaced the dual mass fly wheel again due to damage. If this does not work, They say that they will replace the engine.

They say that there are no other reports or technical bulletins on this problem. You can see in this forum that they have a HUGE problem with this. Are they trying to keep it a secret? My techinician is definitely on my side of all this and he really has never heard of this problem and can't get answers out of VWofA.

Has anyone else had this much trouble? Has anyone persued the lemon law? Anyone get a new vehicle out of it?

 

[SuperJ]

A new engine!
Two flywheels?
I've got to find a dealership that's as liberal as yours with warranty

 

[GoFaster]

I am also worried that the injector will eventually get worse especially after the warranty is up. Also, the vibration must put extral load on the motor mounts causing them to wear out more quickly.

For what it's worth, the occasional uneven idle that mine has, first developed around 20,000 km. The car now has 109,000 km on it, and the situation has not gotten any worse since its initial onset. I don't think this is going to cause any major future catastrophe. It's only a minor irritant.

 

[SpeedFreek]

At least im not the only one, it comes and goes on mine but reving it a little helps. I was worried but nothing ever happened from it.

 

[PDJetta]

I do believe that the what I refer to as the "random idle falter" (which by the way plagues the A4 PDs as well, AND is more pronounced when the vehicle is pointed DOWN a slight incline (hill)) is the result of intentionally retarded injection timing to lower NOx emissions. It most certianly is not excess EGR flow, as I originally thought, because after blocking off the EGR, it still had the idle falter.

That's my belief. Sub optimal, retarded, injection timing on idle to lower oxides of nitrogen.

--Nate

 

[eli]

thanks for all the ideas, folks! yes, i've noticed that running the AC seems to eliminate the possibility of the bouncy idle. i don't really like AC that much, except on the highway or very humid days. but i hope running the AC is a 100% fix for this bouncy idle. i think running the AC bumps up the idle rpm by ~10%, and helps to avoid the lumpy-spot/standing-wave/resonant-frequency/uneven-injector-pulse-width or whatever is happening.
:|

 

[10-cc]

You can run the rear windshield defrost, it will do a great job as well.

 

[srptdi]

I noticed with mine when running on winter diesel I don't have same problem as in the summer months.

 

[eli]

Cool idea, to run the rear defogger elements - Merci beaucoup.
Or maybe I'll just turn on on the passenger bunwarmer and tell them that they'll have to choose between the bouncy idle and steaming buns.
Today when it started rough-idling on me, hit the AUTO (AC) button - and that seemed to work to immediately stop the rough idling.

 

[Vipervnm]

If it is something that's been programmed into the ECU, such as retarded injection timing, shouldn't that effect everyone? I only remember having a slightly rough idle when the engine was cold and it was zero degrees. Other than that I have never had a rough idle issue. For what it's worth, I did have an RC 1+ tune about 3 thousand miles ago. She runs smooth as silk.

 

[CJB3_TDI]

For what its worth – I turn on the rear defrost for 1-2 sec and the idle returns to smooth

 

[mmalluck]

Turning on the air conditioning or electric heater just adds a little load to the engine. The ECU increases the injection quanitity to account for this additional load.

I wonder if monkeying with the default IQ via vag-com could clear this up?