AUA not starting and unable to adapt Throttle Body

[Avantone]

ok deep breath...

2002 1.4 petrol
This started as a code for a misfire on Cylinder 3
VCDS showed a constant misfire count on cylinder 3
Removed coil (4 in 1, not individual packs) and saw corrosion on "C" (3) HT connection.
Cleaned connection and HT lead thoroughly, refitted and VCDS showed zero misfires.
Spark plug is <6 months old looks good. Plug resistance and lead impedance is within spec.
Test drove but still a slight misfire under load.
Engine then went into limp and sounds like its on 3 cylinders.
Drove home (quarter mile) and parked up.
Hypothesis is that coil has been damaged by previous high resistance connection.
Had a new pattern coil handy so fitted to see if condition changed why I wait for a new Bosch item next week.
Car doesn't start... check connections, HT lead positions etc, still doesn't start.
Change back to original coil... Car still doesn't start.

Run VCDS:
17989 - Throttle Actuator (J338)
P1581 - 35-00 - Basic Setting Not Performed
17953 - Throttle Valve Controller
P1545 - 35-00 - Malfunction

Not sure why the throttle body is suddenly an issue.
Check that I haven't knocked a lead/connector off - no visible issues

I've also got a couple of suspect codes on the ABS referencing the ECM

2 Faults Found:
01314 - Engine Control Module
004 - No Signal/Communication - Intermittent
01314 - Engine Control Module
013 - Check DTC Memory - Intermittent

Run VCDS to do a throttle body adaption
Adaption gets 2 steps in and then shows ERROR in the 4th box
Battery on charge and showing 12.5v
Battery disconnected and leads shorted to reset ECU
Battery reconnected showing 12.5v
Cleared codes but codes above return immediately and adaption again shows ERROR after 2 steps
Visual check of ECU is fine. Clean/dry and undisturbed since new
Throttle body was cleaned a couple of months ago and new OEM gaskets used for body and EGR
Checked TB plug and pins - all clean and seem ok

So currently I've done all I can until a used TB and new coil arrive next week.

Any thoughts on what the issue could be? I'm confident the coil is bad, but why have I suddenly got what seems unrelated TB issues, or am I on the wrong track? Earth points, ECU etc?

Many thanks in advance, Tony


Full VCDS autoscan:


Sunday,19,March,2023,11:02:58:08140
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 23.3.0.0 (x64) HEX-V2 CB: 0.4631.4
Data version: 20230228 DS346.1
www.Ross-Tech.com


VIN: WAUZZZ8Z52N012622 License Plate:


Chassis Type: 8Z (8Z - Audi A2 (2000 > 2005))
Scan: 01 02 03 08 15 16 17 18 37 45 46 56 57 75 76 77

VIN: WAUZZZ8Z52N012622
-------------------------------------------------------------------------------
Address 01: Engine Labels: 036-906-034-APE.lbl
Part No: 036 906 034 EG
Component: MARELLI 4MV 4030
Coding: 00051
Shop #: WSC 02138
VCID: 5BE39B027A347C123A1-4B5C
WAUZZZ8Z52N012622 AUZ7Z0A1925514

1 Fault Found:
17989 - Throttle Actuator (J338)
P1581 - 35-00 - Basic Setting Not Performed
Readiness: 1110 0101

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 8Z0-907-379-MK60.lbl
Part No: 8Z0 907 379 C
Component: ESP FRONT MK60 0101
Coding: 0019463
Shop #: WSC 02154 785 00200
VCID: 48C9544EDEA2078A873-5184

2 Faults Found:
01314 - Engine Control Module
004 - No Signal/Communication - Intermittent
01314 - Engine Control Module
013 - Check DTC Memory - Intermittent

-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: None
Part No: 8Z0 820 043 F
Component: A2-KLIMAVOLLAUTOMAT 0510
VCID: 392F218A90486E0208D-2596

10 Faults Found:
00710 - Defroster Flap Positioning Motor (V107)
41-10 - Blocked or No Voltage - Intermittent
01272 - Positioning Motor for Central Flap (V70)
41-10 - Blocked or No Voltage - Intermittent
01271 - Positioning Motor for Temperature Flap (V68)
41-10 - Blocked or No Voltage - Intermittent
00716 - Air recirculation Flap Positioning Motor (V113)
41-10 - Blocked or No Voltage - Intermittent
00727 - Potentiometer in Positioning Motor for Defrost Flap (G135)
30-10 - Open or Short to Plus - Intermittent
00601 - Potentiometer On Positioning Motor for Central Flap (G112)
30-10 - Open or Short to Plus - Intermittent
00600 - Potentiometer On Positioning Motor for Temperature Flap (G92)
30-10 - Open or Short to Plus - Intermittent
00735 - Potentiometer in Positioning Motor for Air recirculation Flap (G143)
30-10 - Open or Short to Plus - Intermittent
00818 - Sensor for Evaporator Outlet Temperature (G263)
30-00 - Open or Short to Plus
01206 - Signal for Duration of Ignition Off Time
27-00 - Implausible Signal

-------------------------------------------------------------------------------
Address 15: Airbags Labels: 8Z0-959-655.lbl
Part No: 8Z0 959 655 E
Component: Airbag Front+Seite 5005
Coding: 01102
Shop #: WSC 02152
VCID: 4EC5625639C6D9BACDF-5160

1 Fault Found:
01578 - Airbag Deactivation Warning Lamp; Passenger Side (K145)
31-10 - Open or Short to Ground - Intermittent

-------------------------------------------------------------------------------
Address 17: Instruments Labels: 8Z0-920-xxx-17.lbl
Part No: 8Z0 920 950 J
Component: KOMBI+WEGFAHRS. VDO D05
Coding: 05442
Shop #: WSC 52227
VCID: 45D75D7AECB01AE27C5-5160
WAUZZZ8Z52N012622 AUZ7Z0A1925514

3 Faults Found:
01304 - Radio
49-00 - No Communications
01314 - Engine Control Module
49-10 - No Communications - Intermittent
01760 - Power Steering Control Module (J500) No comm. with Engine Control Module (ECM)
49-10 - No Communications - Intermittent

-------------------------------------------------------------------------------
Address 45: Inter. Monitor Labels: None
Part No: 8Z0 951 171
Component: Innenraumueberw. D04
Coding: 00001
Shop #: WSC 00000
VCID: 7AADFE86D5CEA51A417-5118

No fault code found.

-------------------------------------------------------------------------------
Address 46: Central Conv. Labels:. 8Z0-959-433.lbl
Part No: 8Z0 959 433 Q
Component: Komfortgerát T1D 0614
Coding: 06858
Shop #: WSC 02138
VCID: 54F1703E17EAB36AFBB-4B00

Subsystem 1 - Part No: 8Z2959802
Component: Tõrsteuer.FS BRM 0001

Subsystem 2 - Part No: 8Z2959801
Component: Tõrsteuer.BF BRM 0001

7 Faults Found:
01330 - Central Control Module for Central Convenience (J393)
37-00 - Faulty
01370 - Alarm triggered by Interior Monitoring
35-00 - -
01371 - Alarm triggered by Door Contact Switch; Driver's Side
35-00 - -
01573 - Alarm triggered by Door Contact Switch; Rear Left
35-00 - -
01561 - Rear left door
61-00 - Won't De-Safe
01562 - Rear right door
59-10 - Can't Unlock - Intermittent
01562 - Rear right door
61-10 - Won't De-Safe - Intermittent

End----------(Elapsed Time: 03:48, VBatt start/end: 12.8V/12.8V)-----------

 

[audifan]

First thing to check is all the fuses are good in the fuse box. do not just look at them but test them with a meter.

If they are all good then take the wiring plug off the coil and carefully check the loom side for corrosion in pins, lack of contact or broken wires.

Rescan the car with VCDS but clear all the codes first to get rid of old codes. Way too many errors in the log to work through.

 

[Robin_Cox]

Our AUA had most of those errors right at the start when there was a bad battery to begin with - which used to go flat, eventually realised it was a crummy aftermarket radio that was still powered up even though the fascia had been removed. Got rid of aftermarket radio for a Chorus, fitted new battery, was able to clear almost all of the alarm and locking errors / HVAC errors / ABS etc. So clear spurious / legacy errors first.

Then I was able to replace the TB / EGR and subsequently plugs, cables, coil, injectors etc., but that resolved most running issues for past 3 years.

Recently had a low battery incident which resulted in TB adaptation status being lost although the car was still completely driveable. Adaptation was unable to be completed owing to recurring error message from main ECU - but this was not engine related but rather "HVAC ECU, check DTCs". Usual bunch of HVAC motor setpoint errors that could be cleared, but the one thing that wouldn't clear was G65 sensor, open to earth. Replaced this and was finally able to clear the HVAC error, which in turn allowed me to completely clear the Engine ECU error codes .. and then finally able to perform adaptation to completion.

One other thing - having cleared HVAC and other errors, you need to turn the ignition off and on again before trying to perform adaptation.

Agree totally with @audifan's suggestions above as well.

 

[Avantone]

UPDATE: Thanks to @audifan and @Robin_Cox.

I was obviously going down a VCDS rabbit hole.

Fuse 20 for the ignition coils had blown. I replaced and the engine started with all of the TB related codes disappearing!
It must of blown when I connected the new but unbranded coil pack.
Lesson learnt and the Bosch coil goes on tomorrow to hopefully solve the cylinder 3 misfire.
I’ve still got codes relating to HVAC but most disappeared when I scanned with the HVAC switched on rather than off!
Thanks again, and fingers crossed on the new coil resolving the misfire.

 

[Robin_Cox]

Misfire should be gone. I also had an intermittent cylinder 3 misfire to begin with, as well as poor idle and EGR fault. Replaced EGR / TB / plugs / cables and fitted refurbished injectors but the intermittent misfire continued. Then started getting worse - 2 cylinders getting shut down and being generally undriveable. That was when I undid the coil and found that the casing was cracked in places with signs of arcing and the silicone potting compound on the reverse was perished and no longer sealed. New unbranded coil was instantly better but failed on one cylinder within a day but that was enough to persuade me to bite the bullet and buy a Bosch which has been fitted ever since.

Best of luck!!!

 

[simon martyn]

"Battersea" is an AUA so I would recommend being in touch with B&F Autos in West Hounslow. Know their stuff and don't charge stupid money. I have learned that things like coils need to be the genuine article. Buy cheap, buy endless times.

Best of luck. and welcome aboard.

PS My coil pack had the minutest of cracks in the casing, virtually invisible. Caused lots of grief.