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Discussion Starter · #1 ·
Good Evening!

I am having issues with my 99 Beetle 2.0L (AEG) Manual Transmission

I have access to a VAG-COM and VCDS.

Current Fault:
Code:
17988 - Throttle Actuator (Bank 1)
    P1580 - 35-00 Malfunction
Since then a few more codes have come up regarding the throttle position sensor and actuator with messages that the signals are implausible. Unfortunately I didn't save them and have disconnected the harness from the ECM to test the wiring harness leads.

I purchased DIY subscriptions to both AllData and Mitchell1 and both show wiring diagrams with way more pins (80 pins) on the connector than what I'm seeing on my connector (I'm counting roughly 54). I'm trying to test the continuity from the Throttle Valve Control Module terminal connector, but the corresponding pins (according to Mitchell and AllData) do not exist.

I'm really stuck in the mud with this one. Any advice would be wonderful. The ECM part number is 06A 906 018 P

VCDS reports Throttle Valve at 70.6% and does not change regardless of pedal position. The Throttle Valve Angle does not change from 0 degrees. The only thing that changes when stepping on pedal is Load Status from Idle to Part Throttle. I have tried a TBA per Ross Tech documentation and get an ERROR.

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Discussion Starter · #2 ·
Sorry, I have a few more things to add.

VCDS reports Throttle Valve at 70.6% and does not change regardless of pedal position. The Throttle Valve Angle does not change from 0 degrees. The only thing that changes when stepping on pedal is Load Status from Idle to Part Throttle. I have tried a TBA per Ross Tech documentation and get an ERROR.
 

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Can you do a full auto scan with vcds and post the scan results?

Can you give us some history of the car and the problems you have had, any repairs and changes, have been done to the vehicle? Thanks.
 

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Discussion Starter · #4 ·
Can you do a full auto scan with vcds and post the scan results?

Can you give us some history of the car and the problems you have had, any repairs and changes, have been done to the vehicle? Thanks.
Hey there, so my father-in-law just purchased this vehicle in Central Texas. It had been sitting outside for approximately 7 months. Last registration expired in July 2020. Engine seems to run well, with exception of a rough idle.

We have replaced the Throttle Body, cleaned the MAF Sensor.

Here is the dump from VCDS as requested. I have also attached a screenshot of a graph obtained while driving the bug (RPM, Load, and Vehicle Speed). I circled the load line where the engine drops out when pressing the accelerator pedal too much.

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Code:
Friday,14,January,2022,12:05:52:61080
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 21.9.0.2 (x64)  HEX-V2 CB: 0.4555.4
Data version: 20210903 DS330.0
www.Ross-Tech.com


VIN: 3VWCA21C8XM400830   License Plate:
Mileage: 169560km-105359mi   Repair Order:



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: 1C - VW New Beetle (1998 > 2010)
Scan: 01 02 03 08 15 17 19 25 29 35 37 39 46 54 56 65 75
 
   Mileage: 169560km-105359miles
-------------------------------------------------------------------------------
Address 01: Engine        Labels: 06A-906-018-AEG.lbl
   Part No: 06A 906 018 P
   Component: MOTRONIC M5.9.2  HS V07 
   Coding: 00000
   Shop #: WSC 00066 
   VCID: 2F3B1C28EE03A5F30EB-4B3C

3 Faults Found:
17988 - Throttle Actuator (Bank 1)
            P1580 - 35-00 - Malfunction
00282 - Throttle Position Actuator (V60)
            27-00 - Implausible Signal
16487 - Mass Air Flow Sensor (G70)
            P0103 - 35-10 - Signal too High - Intermittent
Readiness: 0000 0100

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 1J0-909-60x-VW3.lbl
   Part No: 1J0 909 609
   Component:  F AIRBAG VW3 SG   0002 
   Coding: 00070
   Shop #: WSC 00066 
   VCID: 6C81CB241F951EEB6B9-4B9A

1 Fault Found:
01217 - Side Airbag Igniter; Driver Side (N199)
            32-10 - Resistance Too High - Intermittent

-------------------------------------------------------------------------------
Address 17: Instruments        Labels: 1C0-919-95x.lbl
   Part No: 1C0 919 951 C
   Component: KOMBIINST.      M73 V20 
   Coding: 02242
   Shop #: WSC 131071 
   VCID: 290FF230D0E7CBC3D0F-4B3C

1 Fault Found:
00771 - Fuel Level Sensor (G)
            30-10 - Open or Short to Plus - Intermittent

End----------(Elapsed Time: 04:19, VBatt start/end: 14.2V/14.1V)-----------
 

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The first thing, i would do; is confirm, the sensors are being read by viewing live data. If not, i would be checking thr plug and wiring harness, possibly fuses or relays for problems.

If they are ok; then, cleaning the throttle body and doing the “cable driven” throttle body alignment procedure would be next. (Documented on the Ross Tech site; e.g. “Cable-Throttle Engines”):



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Discussion Starter · #9 ·
The first thing, i would do; is confirm, the sensors are being read by viewing live data. If not, i would be checking thr plug and wiring harness, possibly fuses or relays for problems.

If they are ok; then, cleaning the throttle body and doing the “cable driven” throttle body alignment procedure would be next. (Documented on the Ross Tech site; e.g. “Cable-Throttle Engines”):



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Thank you for the information, the throttle body is brand new and functioning properly, and I am getting the same readings as with the old throttle body. I attempted an alignment and received an error. Is there a possibility that the ECU has gone bad? I have been unable to find the proper pin-out diagram to check the wires from the ECU connector to the Throttle Body and MAF connectors to ensure there are no shorts and that there is continuity.
 

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Discussion Starter · #10 ·
The MAF sensor gives numbers in accordance with RPM, but I'm not sure what exactly they should be. At current idle (1100 RPM) I get around 8.5g/s. While driving it, I believe I've seen it get to around 40g/s at around 3000 RPM
 

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For the maf sensor; again, live data; is the best way to confirm it is working in spec. For replacement maf sensors; stick with oem Bosch parts, aftermarket versions, tend to not work correctly and even, cause limp mode. If you have a aftermarket maf; you might compare rhe readings; by cleaning your old one and putting it back in, see if they read differently and how the car runs with the swapped parts.

Here is a overview of testing procedures; maf readings, should be take @ idle, @ wide open throttle in second gear and the readings should show-a smooth transition to min to max, not a bunch of jumping around (another classic sign of a failing maf).


Report back your troubleshooting, tba procedure and we can go from there, thanks.


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Discussion Starter · #12 ·
For the maf sensor; again, live data; is the best way to confirm it is working in spec. For replacement maf sensors; stick with oem Bosch parts, aftermarket versions, tend to not work correctly and even, cause limp mode. If yij have a aftermarket maf; yiu might compare rhe readings; by cleaning your old one and putting it back in, see if they read differently and how the car runs with the swapped parts.

Here is a overview of testing procedures; maf readings, should be take @ idle, @ wide open throttle in second gear and the readings should show-a smooth transition to min to max, not a bunch of jumping around (another classic sign of a failing maf).


Report back your troubleshooting, tba procedure and we can go from there, thanks.


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Okay, so I've done a few things after reviewing the information you've provided. I'll provide responses based upon your links to Ross-Tech and explain my additional findings.

P1580 - Throttle Actuator Bank 1 Malfunction - Disregarded as TB is brand new and old unit had same TPS percentages.

00282 - Throttle Position Actuator - When no Cruise Control is present, TB is only other cause listed.

P0103 - 35-10 - Signal too High - Intermittent - I will replace the MAF ASAP as an OEM sensor can be sourced.

TBA - Attemped TBA several times using both Group 060 and 098 all resulting in ERROR

(Most Recent billymade post) - Although I wasn't able to figure out how to export the live data, the MAF sensor seems to be reading within spec (up to the point in the throttle until engine cutout, around 30% depress on pedal at idle / level driving, 25% up hills, 35% down hills). Couldn't figure out how to export live graphs. Given that I am unable to give the vehicle WOT and not have the engine return to idle, that is the best information I can provide for that issue. Existing MAF was cleaned and is an OEM part.

On further reading of the PDF in the last post, I checked the fuel trim values and noticed that in a 20 minute drive, the numbers (Group 032) did not change at all.

Code:
12:18:38 Group 032: Lambda Control (Mixture Adaptation)
    17.2% Adaptation (Idle) Bank 1 Sensor 1
    5.5% Adaptation (Partial) Bank 1 Sensor 1
It is my understanding that spec range is ~+/- 10% and that if additive (idle) is positive and out-of-spec that there is a vacuum leak. My concern is that these numbers did not change at all in a 20 minute drive.

Thank you again!
 

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The question might be confusing; which part is causing the throttle body alignment problem and drivability issue.

I think, I would start with solving the throttle body relayed issues and then, possibly other problems will fall into place and be resolved. A car that has lost its throttle body settings will run horribly and a bad maf, can cause, the car to go into limp mode.

A “fail” status, when doing the “tba”; is common; NOTE: the specific conditions, that must be met, for the programming, to be completed successfully. At times, i have had to hookup a battery charger or jumper cables; to maintain, the required 12.5V on a weak or dead battery (just one thing; on the list).

There are certain test conditions that must be met before doing a TBA:

No DTC's in the Engine Controller

Battery voltage at least 11.5 V

Throttle must be at idling position (keep your foot off the gas pedal)

Throttle body part must not be dirty (carbonized).

Coolant temperature must be between 5 and 95C

If fault codes were cleared cycle the ignition off and back on prior to running Basic Settings.


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Discussion Starter · #14 ·
I have finally solved the issue, I think.

Turns out the issue stems from two items. The fuel filter needed replacement, solving the limp mode / load shed issue. Haven't been able to perform a TBA due to improper adjustment of the accelerator pedal cable. I will adjust it and perform a TBA per spec and return with results.

After changing fuel filter and test driving, resultant fault codes are:

Code:
01165 - Throttle Body Control Module (J338)
    55-10 - Adaptation Not Successful - Intermittent
    
17973 - Throttle Actuator (J338)
    P1565 - 35-00 - Lower Stop not Reached
    
17988 - Throttle Actuator (Bank 1)
    P1580 - 35-00 - Malfunction
 

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Good work, sounds like you are making progress; if fuel delivery is still suspect, a fuel pressure test, could confirm that issue and fuel trims, is another quick way, to confirm the tune of the engine (+ or - 10% are considered; in the normal range).

Throttle valve codes, could be a result of the cable adjustment and loss of tba settings.

You are working through things; multiple problems at once, can make things confusing to diagnose.

PS: after you get the tba finished; you might recheck and test your maf, many go back to their original Boach oem maf, as the aftermarket versions, don’t read airflow to spec.


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