2.0l TDI fluctuating tickover

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tubby_tony

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Hi ppl,

My 2006 A3 2.0l TDI has developed a problem. When the engine is at running temperature and idling it sits at 800 rpm then after ~30 seconds the revs jump to 1000 rpm and idles for 30 seconds then drops back to 800 rpm and repeats this process. Any suggestions?

Thanks
 
Dirty EGR valve, leak in intake system or bad quality battery could be the causes. Also the torsion value or temperature sensor. You will need to check all of these unless someone comes with a better advice. :)
 
All of the above plus an effed injector...I'd deffo clean the EGR and order fresh seals from TPS, helped massively with my car.
 
Thanks for suggestions. I will be getting her connected up to diagnostic tools today so hopefully will find some error codes. Cleaning the EGR and turbo has been on the cards for this year so will be getting done over the next couple of weeks.
 
If ur man with the scan tool looks at air mass when it's doing the fault, reading will drop during fault as engine takes unmetered air from somewhere (either egr/air leak). Blanking off EGR and doing an intake smoke test for leaks are a couple of easy and worthwhile initial steps.
Plus 1 to potential fuel delivery issue.
 
here is part of the diagnostics print out of interest

00-Steering Angle Sensor -- Status: OK 0000
01-Engine -- Status: Malfunction 0010
03-ABS Brakes -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: Malfunction 0010
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: OK 0000
22-AWD -- Status: OK 0000
25-Immobilizer -- Status: OK 0000
37-Navigation -- Status: OK 0000
42-Door Elect, Driver -- Status: OK 0000
44-Steering Assist -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
56-Radio -- Status: OK 0000
62-Door, Rear Left -- Status: OK 0000
72-Door, Rear Right -- Status: OK 0000
76-Park Assist -- Status: Malfunction 0010
77-Telephone -- Status: OK 0000
7D-Aux. Heat -- Status: OK 0000


-------------------------------------------------------------------------------
Address 01: Engine Labels: 03G-906-018-BMN.clb
Part No SW: 03G 906 018 DN HW: 03G 906 018 DN
Component: R4 2.0l PPD1.2 G 4350
Revision: --H22--- Serial number: AUX7Z0F8FN807C
Coding: 0000172
Shop #: WSC 00435 210 95082
VCID: 74E324D1173C06817A7-8021

No fault code found.
Readiness: N/A

-------------------------------------------------------------------------------
Address 09: Cent. Elect. Labels: 8P0-907-279-23-H.lbl
Part No SW: 8P0 907 279 F HW: 8P0 907 279 F
Component: Bordnetz-SG H43 1201
Revision: 00H43000 Serial number: 00000006200813
Coding: E1885F01B214100000160000160000000008FE175C0100
Shop #: WSC 06314 000 08192
VCID: 408BB8011304EA212EF-8015

Subsystem 1 - Part No: 8P2 955 119 E Labels: 1KX-955-119.CLB
Component: Wischer AU350 H01 0130
Coding: 00062736
Shop #: WSC 06314

Subsystem 2 - Part No: 4E0 910 557 A Labels: 8K0-955-559.CLB
Component: REGENLICHTSENSORH12 0090
Coding: 00150573
Shop #: WSC 06314

1 Fault Found:
01598 - Drive Battery Voltage
000 - - - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 2
Fault Frequency: 124
Reset counter: 142
Mileage: 208450 km
Time Indication: 0
Date: 2015.06.09
Time: 15:50:00

Freeze Frame:
ON
Voltage: 13.45 V
ON
ON
OFF
OFF
ON

-------------------------------------------------------------------------------
Address 76: Park Assist Labels: 8P0-919-283.lbl
Part No SW: 8P0 919 283 D HW: 8P0 919 283 D
Component: Parkhilfe 4-Kan H09 0060
Revision: 00H09000 Serial number: 00067824820625
Coding: 0000113
Shop #: WSC 131071 1023 2097151
VCID: 3C73CCF17FEC8EC1727-8069

2 Faults Found:
01546 - Sensor for Parking Aid; Rear Mid-Left (G204)
009 - Open or Short to Ground
Freeze Frame:
Fault Status: 01101001
Fault Priority: 3
Fault Frequency: 104
Reset counter: 103
Mileage: 194548 km
Time Indication: 0
Date: 2014.07.06
Time: 00:20:43

01546 - Sensor for Parking Aid; Rear Mid-Left (G204)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 3
Fault Frequency: 40
Reset counter: 143
Mileage: 206060 km
Time Indication: 0
Date: 2015.05.15
Time: 06:36:22


Its weird that the summary reports an engine malfunction but no fault code found.

From the list of suggestions above is battery suspect?

Any more ideas?

I will try and get the air mass test done.


Thanks.
 
I've had this problem and solved it yesterday!

What I did is connect the +12V of the battery to the fuse box in the engine bay (actually to one of the screws which are at the front of the fuse box).

The part of the cable that leads from alternator to the battery was damaged in between fuse box and the battery itself so this solved it completely, no more self-reving-up-Audi. :D

Basically the cable could not transfer enough electricity to the battery, and car tried to rev up the engine to produce more power on alternator so the battery can get fed properly.
 
Cleaned the throttle body, EGR valve and inlet manifold at the weekend. What a mess! I will get the turbo cleaned in a couple of weeks time. Any way, problem is still there so I will continue exploring the suggestions. I will try the battery in the mean time until I can get diagnostics kit on it again.
 
Sorry Rideen, should of clarified your suggestion is what I intend to try. You got a picture of how you have connected it up? Thanks.
 
Hey mate, my mechanic did it so it cannot be seen at all, but here are 2 pictures demonstrating how we found out it is an issue and how did he connect it (I used Paint to do some overlay lines):

He checked for broken wires by connecting the +12V on the battery to the + side of the alternator directly by a cable, as on the picture 2 while monitoring the voltage on the battery itself. Since the voltage started increasing when this cable is attached, that meant that somewhere in between the alternator and the battery the wiring is damaged.

Then he connected the + on the alternator to the metal bracket on the fuse box (all the cables lead into it, you can easily spot it). Since the voltage remained as in the previous step, the connected the + on the fuse box to the + on the battery. The voltage went up, so we knew that the damaged wiring was somewhere in between the fuse box and the battery. He finally just used some wire to connect the +12V on the battery to the fuse box metal bracket (+).


First picture is how he connected the battery to the fuse box (he did the wiring behind the plastics though), uploaded this only as a reference.

Audi a3 20 tdi 140 induction kit dynatwist by green cotton dwa160 2 28909 p Rasuba6e
 
Cheers mate. I looked in the fuse box tonight and saw that there was a spare connection stud on the metal plate that a cable could be connected to. I will do the tests at the weekend with a voltmeter when it shows the problem. If this is the solution I would prefer to replace the damaged lead but firstly it will just be piece of mind in identifying the problem. I will update the thread with my findings at weekend. Thanks again.
 
audi upgrades
No problem mate, just bear in mind that a fix like mine will cost you 10 pounds and a complete cable replacement probably over 100.
 
Tonight when car was showing accelerated tick over of 1000rpm when engine was at running temperature I switched her off and grabbed a voltmeter and waited a few minutes. I checked the battery and she was sitting at 12.48V (I think). Started her up and she was ticking over at 800rpm and showing 13.54V. Over the next minute I saw the voltage slowly drop to 13.4V and then the engine revs went up to 1000rpm and voltage climbed back to 13.5V. So I guess I need some 4 AWG wire as alternator output is 140 amps (?). Rideen did your mate put an in-line fuse in your wire and if so what ampage? Thanks.
 
He just connected the metal terminal on the fuse box to the battery. Now that you asked this, it got me wondering that he should have probably put a fuse...
 
You need to do voltage drop tests to check u alternator power connections. So to rule out the alternator wiring: voltmeter battery + to alternator b+ (under load) if u see> 0.5v that's not good -> renew wiring. To rule out simply connect jump lead in same way as voltmeter. If fault disappears, happy days.

Worth checking main earths this way too.

Ps- if ur alternator has a 3 pin connection it's a smart charge unit so voltage will fluctuate depending on its state.
 
Thanks for info fouryoghurts. Just to confirm, when you say "To rule out simply connect jump lead in same way as voltmeter. If fault disappears, happy days." you are meaning that this action confirms that I need to replace the wiring? As a temporary measure I could put a 4 AWG wire in between alternator and battery connected between these two points? Would it need to be fused? Thanks for everyone's help.
 
tubby_tony said:
Thanks for info fouryoghurts. Just to confirm, when you say "To rule out simply connect jump lead in same way as voltmeter. If fault disappears, happy days." you are meaning that this action confirms that I need to replace the wiring? As a temporary measure I could put a 4 AWG wire in between alternator and battery connected between these two points? Would it need to be fused? Thanks for everyone's help.
Click to expand...

So, to clarify, if you are having problems with voltage drop on your heavy power to alternator wire, connecting a jump lead from your battery positive to your alternator B+ (positive connection from battery) provides a known-good path with zero resistance (in an ideal world, if your leads are decent) from battery positive to alternator B+, essentially eliminating the voltage drop present on you original battery pos to alt B+ wire.
As per my previous post, this can be checked with a voltmeter so you know if you need to bother with this step though. If you're seeing a volt drop of less than ~0.5 volts (less than 0.25v ideally) your B+ to alternator isn't causing any issues so move on with your checks. Remember to always check circuits for volt drop under electrical load i.e. switched on and doing what they're supposed to be doing.

Regarding your temporary B+ wiring measure...yes, you can do this if you can't do the volt drop tests and want to see if it cures things. This would most definitely need to be fused and i'd make sure it stays temporary :p. For something like this I'd recommend going OE. If you need help with part numbers or anything else, let me know and i'll try to help. Good luck.
 
Last edited:
Checked it with the voltmeter and I am seeing 0.27 volts with all lights on, aircon and radio blasting and she is sitting at 1000 revs. I did notice that tonight she started doing this revving up before she was warmed up, at around 50 degree c.
 
tubby_tony said:
Checked it with the voltmeter and I am seeing 0.27 volts with all lights on, aircon and radio blasting and she is sitting at 1000 revs. I did notice that tonight she started doing this revving up before she was warmed up, at around 50 degree c.
Click to expand...

From that I wouldn't expect this is causing fault. That said, on a heavy line, i'd prefer it was zero.
Worth checking volt drop on earth return too. Connect one lead of volt meter to battery -ve, the other to eng block/gear box. Load up as above. If you get a high value, zero in on gearbox earth strap quality/condition.
 
Now I am a bigger idiot. While taking the nut off the alternator b+ connector in order to obtain more thread to connect my jump lead, my spanner caused a spark as it touched a neighbouring metal pipe. I thought I heard a pop sound from the fuse box but on checking the fuses they all looked fine. Anyway, re-secured nut and started engine and damn alternator warning light remains on, (red battery light). Checked voltage across battery with engine running and should see around 13.4v but only seeing 12.2v. Do I need new alternator or is there a fuse I can't see?
 
Heavy fuse likely. PM VIN & Reg and I'll pull vehicle specific info.
PS - You can check if fuse has gone by checking continuity between Alt B+ and Bat +VE.
 
Last edited:
Yes, that voltage measurement should be 0V. It'll be fuse 1 (150/200A left-most) of the heavy fuses in engine bay (I think they are mounted vertically).
To confirm you can use your jump lead between alt b+ and batt +ve.
*PLEASE BE CAREFUL NOT TO SHORT WHEN CONNECTING - Note - it should really be a fused lead, so again, take extra care when connecting if you chose to do this. When you start engine battery waring on dash should be extinguished -> new fuse time.

PS - let me know fuse colour and I can get part no...they're £4ish.
 
Last edited:
Excellent. Thankyou. I will check this tomorrow evening and get back to you. Good excuse to use the tubby for travel to work.
 
This is strange. All I did on saturday was disconnect the battery and changed the fuse. Since then there is no revving up to 1000 rpm when idleing. The battery leads looked secure before I took them off so I dont think it was that. Fingers crossed.
 
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