Stuttering and hesitating at constant speed

[Hobb99]

Well I finally got around to cleaning the EGR valve and the air flap (anti shudder valve) this weekend.

Overall I was quite disappointed how clean both valves were (was expecting them to be in far worse condition).

Two reasons drove me to attempt the clean:

1. A few weeks ago I'd had to call on the services of Audi Assist to clear the emissions light on the dash. When he inspected the codes, it came up with an air flap failure. The light had come on after several failures. He reset, tested it and gave it the all clear.

2. I've been having a progressive condition where the car stutters and hesitates when running at a constant 1500-2000 rpm. The problem is getting worse.

I removed both EGR & Air valve, stripped them both down, cleaned them, and opened the access to the motor gearing. Both were in pretty good condition. I was expecting the drive gears in the air flap to be broken or damaged, but this was not the case. Both EGR & air flap valves opened ok, so all I did was to use some EGR cleaner and tidy them up. Got some new gaskets from Audi & built them back up.

The first drive seemed ok - perhaps a little slower on pull-off than I remembered, but seemed smooth. Great I thought - cracked it!!


Until on my way back from my little outing, I was running at about 50mph and 1500rpm and the car decided to stutter and hesitate again. Not a happy bunny!!!


So I'm now wondering what else the problem can be? I've read about the fuel filter being a potential source but that doesn't make sense as on acceleration its absolutely fine. Also, if the car starts to hesitate if I either take my foot off the pedal or floor it, everything is ok until the car returns to a constant speed.


Thought it might have been the accelerator potentiometer, but this is negated as the car continues to jump around when I'm on cruise control.


Ideas anybody? MAF? O2 sensor? timing sensor? All help very welcome.

Cheers

Mark

[Guest 2]

Does your car have a DPF? Could be a regen as I know my A3's engine stutters and shakes at speed when it's doing it.

[Hobb99]

Hi Chris

Yes it does have a DPF.

I did wonder if this could have an effect, so early last week whilst driving the 90 miles home, I put the box into manual and ran for a good half of the journey in 5th & 6th to keep the revs up close to 3000rpm.

Exhilerating to say the least!

Not that it made a great deal of difference!

Surely a blocked DPF would cause problems with acceleration? I dont seem to have that issue.

Mark

[Guest 2]

DPF won't cause acceleration issues, just the stuttering during a regen which I mentioned above.

Does your rev needle move when this is happening?

[Hobb99]

Yes. The needle bounces around by anywhere upto 300rpm.

Backing off or flooring the accelerator stops the stuttering for a while.

[Guest 2]

Hmm not DPF then.

Have you had it on the computer?

[Hobb99]

Was going to do that this evening. I'll post the results later.

[Hobb99]

Ran VCDS this evening - no engine faults showing - and it was a mare this morning!

I haven't registered the DAB yet, I know of a fault on the Bose, but there is a fault showing on the CAN Gateway but not sure what is.

Here is an excerpt.

00-Steering Angle Sensor -- Status: OK 0000
01-Engine -- Status: OK 0000
02-Auto Trans -- Status: OK 0000
03-ABS Brakes -- Status: OK 0000
05-Acc/Start Auth. -- Status: OK 0000
07-Control Head -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: OK 0000
0E-Media Player 1 -- Status: OK 0000
0F-Digital Radio -- Status: Not registered 0011
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: Malfunction 0010
25-Immobilizer -- Status: OK 0000
37-Navigation -- Status: OK 0000
42-Door Elect, Driver -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
47-Sound System -- Status: Malfunction 0010
4F-Centr. Electr. II -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
53-Parking Brake -- Status: OK 0000
56-Radio -- Status: OK 0000
61-Battery Regul. -- Status: OK 0000
62-Door, Rear Left -- Status: OK 0000
72-Door, Rear Right -- Status: OK 0000
76-Park Assist -- Status: OK 0000
77-Telephone -- Status: OK 0000

-------------------------------------------------------------------------------
Address 01: Engine Labels: Redir Fail!
Part No SW: 03G 906 016 GC HW: 03G 906 016 GC
Component: R4 2,0L EDC G000CG 9887
Revision: --H05--- Serial number:
Coding: 0000076
Shop #: WSC 66565 257 00032
VCID: 6ADFC69B3CEF

No fault code found.
Readiness: 0 0 0 0 0

-------------------------------------------------------------------------------
Address 02: Auto Trans Labels: 01J-927-156.lbl
Part No SW: 4F2 910 155 H HW: 01J 927 156 JG
Component: V30 01J 2.0l PD RdW 0010
Revision: --H03--- Serial number: 00000000000165
Coding: 0000001
Shop #: WSC 02325 785 00200
VCID: 295DF997F969

No fault code found.

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 4F0-910-517.lbl
Part No SW: 4F0 910 517 AC HW: 4F0 614 517 T
Component: ESP8 front H01 0070
Revision: 00000000 Serial number: 00000000000000
Coding: 0020856
Shop #: WSC 02325 785 00200
VCID: 65C5B5A7D5F1

No fault code found.

-------------------------------------------------------------------------------
Address 05: Acc/Start Auth. Labels: 4F0-910-852.lbl
Part No SW: 4F0 910 852 HW: 4F0 905 852 B
Component: FBSAUDIC6 ELV H31 0220
Revision: 31050601 Serial number: 10601100704091
Coding: 0000147
Shop #: WSC 02323 785 00200
VCID: E3C12BBF5BC5

Part No: 4F0 910 131 E
Component: FBSAUDIC6 EZS H45 0080

Part No: 4F0 910 220 D
Component: FBSAUDIC6 IDG H01 0040

No fault code found.

-------------------------------------------------------------------------------
Address 07: Control Head Labels: 4F0-910-7xx-07-H.lbl
Part No SW: 4F1 910 732 D HW: 4E0 035 729
Component: Interfacebox H43 5570
Revision: 00000000 Serial number: 350BO077763615
Coding: 0001002
Shop #: WSC 02335 785 00200
VCID: 2545F5A79571

Part No: 4F0 910 609 E
Component: Bedienteil MMIC6H01 0060

No fault code found.

[Guest 2]

The CAN gateway error will be an incorrectly coded message due to not registering the DAB in the CAN.

No idea on the stuttering though, sorry. I'll have a look on the forum though and see if anything relevant appears and post it up.

[gupsterg]

1. A few weeks ago I'd had to call on the services of Audi Assist to clear the emissions light on the dash. When he inspected the codes, it came up with an air flap failure. The light had come on after several failures. He reset, tested it and gave it the all clear.

2. I've been having a progressive condition where the car stutters and hesitates when running at a constant 1500-2000 rpm. The problem is getting worse.

On the inlet manifold is a vacuum actuator which controls the flaps to allow more air ...

google for SSP412 Audi 2.0l 125 kW TDI Engine with Pump Injection System view page 14 ...

It maybe something to check?

Sorry can't give any more insight ...

ATB
G