rough idle, 5-spd

eli

Veteran Member
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Oct 22, 2002
Location
I-95
TDI
2017 Cruze stickshift 2019 Terrain
dealership compared my 06 with some 07s they have.
"They all do that". Oh well.
 

AudiMatt

Well-known member
Joined
May 16, 2006
Location
Gresham, OR
TDI
2010 JSW TDi DSG
We finally got our Jetta in for the rough idle about 2 weeks ago. Of course the tech pulled codes and found "nothing wrong." Well, VW sent us a satisfaction survey and I informed them I wasn't satisfied...

Within 3 days the Dealership was calling us wanting to us to bring in the car for their "specialist." He's the shop foreman and has been there a while. Took him for a test drive and of course the car only acted up once but he decided to go after the EGR valve...

EGR valves for the PD are back-ordered and there are supposedly none available in the US. He removed and cleaned the EGR valve. According to VW the EGR valves can get blocked up with carbon do to running on non-ULSD. Apparently they have seen some that are just completely plugged off!??

We went in yesterday for the test drive etc... and got the car back last night. My wife says that it idled and drove like new last night with no rough idling or bouncy tach when cruising. Unfortunately, this morning it went right back to it's old ways. If the issue is in fact with carbon in the EGR then it has gotten clogged again from someplace downstream or that is not the problem at all. I have a call in to the dealership and they are going to call back when they figure something out.
 

GoFaster

Moderator at Large
Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
It's not the EGR, this was ruled out a long time ago. There was discussion of this in another thread. You can disable the EGR system completely, and disable the intake flap "throttle", and the MIL warning lamp will be lit due to the EGR malfunction because the engine is breathing in unrestricted clean air, and if the car was prone to rough idle, it will still idle rough with the EGR and throttle completely bypassed. Therefore this is not the cause.

I'm rather sure it is an ECU programming issue and it's possibly related to the way the system corrects for normal minor imbalance between injectors (they can *never* be balanced perfectly, the ECU is supposed to adjust for this). There is nothing "wrong", per se, because the car is performing as per original specifications. The fault is "designed in" and this is why "they all do that" is pretty close to being correct. The only ones that don't, if my hypothesis is correct, are the ones that miraculously have the injectors balanced close enough for the ECU to not have to compensate too much (translation: it's still idling rough, but it's too subtle to notice). Faults like that normally cannot be resolved at a dealer level.
 

AudiMatt

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Joined
May 16, 2006
Location
Gresham, OR
TDI
2010 JSW TDi DSG
If it something that can't be solved at the dealer level, how/where can it be solved? Or, better yet, how can I convince the dealer to solve it?

My wife is not going to be willing to just pretend the rough idle isn't there... And she really isn't a disagreeable person...
 

eli

Veteran Member
Joined
Oct 22, 2002
Location
I-95
TDI
2017 Cruze stickshift 2019 Terrain
audimatt, does turning on the electric mirrors or rear window defogger eliminate the jumpy idle.
I agree with you that it is at least partially a software issue. I think a reason software/ECM can't fix it is that ECM has no way to know that the car is bouncing like Dolly Parton on a trampoline.
I believe the issue is related to the resonant-frequency of the vehicle, and a standing-wave that occurs sometimes.
Possibly a bugfix for the software would be to just bump up the target-idle speed by 50 rpm. However that would surely have emissions implications, as well as mpg-at-idle implications.
I think that turning on the AC and heating-elements on DOES increase the rpm slightly, by design.
Anyway, very hot weather is almost here, so I expect I'll be running the AC nonstop for the next few months, and I'm hoping that will prevent the "lumpy idle" .
 

oldpoopie

Vendor
Joined
May 14, 2001
Location
Portland Oregon
TDI
2001 golf gl, 2006 jetta, 1981 ALH swapped rabbit pickup, 1998 beetle
I'm with the resonant frequency thing. Do any of the cars experiencing it have a DSG transmission?
 

GoFaster

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Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
DSG owners have mentioned this, too.

The only way this is going to get fixed is if someone (VW or otherwise) gets to the bottom of the software problem. I have a funny feeling that this is going to be a low priority task: (1) It is not a safety-related issue, so NHTSA won't intervene. (2) It is not an emissions-related fault, the car will still pass emission tests while idling rough, so EPA won't intervene. (3) It does not interfere with the car's primary function - you will still get to where you need to go despite this. (4) In the scheme automakers use to prioritize repairs, this is regarded only as a "driver irritant". (5) The vehicles in question (Mk5 P-D) are no longer being produced new.
 

gawelnj

Veteran Member
Joined
Aug 7, 2006
Imbalance between injectors is indeed the issue here. Reading the cylinder adjustments of IQ from the advanced measuring blocks section, I noticed cylinders 1+2 were running -2mg/str, cyl 3 @ -0.5, and cyl 4 at +1.5!

Although they are in spec, and somewhat slight, it is enough to make the diesel idle rough, due to the imbalance in power output between cylinders.
 

fueg0

New member
Joined
Dec 16, 2006
Location
Pflugerville, TX
TDI
Jetta
I don't think it's the fuel filter- my 2005.5 has about 1500 miles on a new filter, and my car shakes a tad when I come to a stop. give it a little fuel & it goes away.

I'm glad it's happening to other people. I was starting to think I'd lost my mind...

--jeff
 

06SpiceRedTDI

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Joined
Jun 12, 2006
Location
Longview, WA
TDI
2006 Spice Red TDI Jetta, 2006.5 DSG Platinum Gray TDI
I lived with this for 20000 miles, until my Clutch DMF came apart. I got my car back from the dealer with a new clutch and flywheel and my rough idle seems to have almost completely disappeared. DMF failing=rough idle? mabye the engine is trying to compinsate for the imbalance of the flywheel. Is this happening on any 06.5 SE cars, or any 06 cars built after 3/06?
 
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SootHappens

Veteran Member
Joined
Jul 11, 2006
Location
Scappoose, OR
TDI
2006 Jetta TDI
Maybe the DMF is 'causing' the rough idle, but I doubt the engine has the appropriate sensors to try and compensate for a flywheel imbalance. I heard somewhere that the flywheel 'might' be dampened by some sort of fluid (not verified) and if that leaked, or got trapped in a baffle it might cause an imbalance:confused:
 

ReverendVW

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Aug 9, 2007
Location
Spokane, WA
TDI
VW Shop Owner
So it appears that my first post to this forum will be here.
I haev personally resealed no less than 15 Injection pumps now due to fuel changes. and on this very latest one, have gotten this problem to occur. Inj quantity seems to be imbalanced, but then again all the cylinders are shaped differently, so maybe the one needs more than the other.
I think for the benifit of all, I will play with the quantity adjustment today, and see if I can smooth it out.
 

SuperJ

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Apr 11, 2006
Location
Waterloo, ON
TDI
2006 Jetta TDI
Is it possible to adjust injection quantity with a VAG-com on PDs? I thought only ALHs could have that happen.
 

GoFaster

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Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
Not possible with the EDC16 engine controls. (It's an EDC16 versus EDC15 thing, not a P-D versus distributor-pump thing, although it so happens that all P-D's in North America are EDC16.)
 

mannyaplus11

Well-known member
Joined
Jan 31, 2007
Location
Valencia, CA
TDI
2006 Jetta
I had the same rough idle problem. My dealership said there is a TSB for a motor mount. They replace the mount and the rough idle went away.
Something simple for a change, go figure.
 

Kier

Veteran Member
Joined
May 14, 2004
Location
Trenton NJ
TDI
2006.5 Jetta Limited Diesel Edition, DSG, Reflex Silver/Anthracite
fireice said:
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
I had the exact same issue with my 04 Jetta TDI Wagon. When I was at a stop light (engine fully warmed up) I experienced the same shaking. The dealer performed the EGR GAS COOLER replacement under warrenty and this apparently fixed the shaking issue. Not sure if they worked on anything else since the service ticked stated "replaced gas cooler". The shaking was bad and I could see the engine shaking so bad I could not read any of the labels on the motor. My wagon was totalled in an accident and now I drive a 2006.5 Jetta Diesel Edition Sedan. No issues so far (only 600 miles).
 

GoFaster

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Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
The EGR cooler thing was a Mk4 thing, the same situation does not apply to the Mk5's that are the subject of this thread.

The engine mount situation is an interesting one. It won't be on NHTSA because it's not a safety related problem, but if there is a TSB from the manufacturer, it would be interesting to track that one down ...
 

ReverendVW

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Aug 9, 2007
Location
Spokane, WA
TDI
VW Shop Owner
sorry, I just noticed this was a mkv forum, but maybe it will help you guys.
I adjusted the inj. pump manually, and got the problem to smooth out. ti appears that you can adjust the quantity, but be very careful...I moved the pump 1mm, and got massive quantity increase. In the end I ended up adjusting it about .020", and got the right adjustment.
 

SuperJ

Veteran Member
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Apr 11, 2006
Location
Waterloo, ON
TDI
2006 Jetta TDI
To adjust PD injectors you'd have to shim the injectors up or down or shave the plunger or something. They run off of a rocker arm on the camshaft so adjustment really isn't an option.
 

SootHappens

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Jul 11, 2006
Location
Scappoose, OR
TDI
2006 Jetta TDI
ReverendVW said:
It's not something laying around the engine bay. It's on top of each injector.
I think I see what you're talking about... But wouldn't that adjustment be for adjusting clearences, not injection quantity?


Most of our motors don't shake 'all the time'... my thoughts would be, that adjustment would have little or no effect on the way it runs unless it was too loose (clicking) or too tight and bottoms out the injector plunger...

I don't have a Bentley manual, so I can't really pull any weight with my theories... Just my .02

I think it may be related to fuel, or the remote possibility of carbon/soot build up on a valve maybe keeping it from closing completely somtimes.
 
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