Jetta 2.0 Mk.4

[Hubaro]

Hi everyone! This is my first post. I have a 2004 Jetta MK4 with a 2.0L engine. I’m relatively new to car repair, so when I bought it, I took it to two different mechanics to fix any issues. However, none of them could solve a persistent misfire that occurs when I fully press the accelerator. To take matters into my own hands, I got the schematics and a HEX-2 tool to try and diagnose and repair it myself.

Currently, my car misfires, and after idling for about a minute, it starts to smell like gasoline. I haven’t driven it with this issue. Before this, I replaced my ignition coil with a cheap aftermarket one, which turned out to be a mistake. The insulation under the coil cracked, likely causing the transformer to “spark” directly to the chassis. I’ve since replaced the ignition coil, spark plug wires, and spark plugs with Bosch parts (models F000ZS0210, 0986MG0307, F6DTC), checked the resistance of the spark plug wires, and tightened the spark plugs to the recommended 18 lb-ft torque. Despite these changes, the problem persists.

Before the aftermarket coil cracked, the car would occasionally lose power and misfire, making it vibrate for about 10–15 seconds before running normally again. Eventually, the misfires became constant, likely when the coil cracked and started discharging directly to the chassis instead of through the spark plugs.

Alongside replacing the ignition coil and plugs, I swapped out all the fuses by the driver’s door with the correct AMP values per Elsawin, as some were above spec. After that, I got a new code from the ECM (01314 - no communications, intermittent), in addition to the fault codes I had before replacing the cheap aftermarket coil: P0108, P0113, P0300, P0304, P0302, P1171, P0301, and P1356.

Before all of this, I attempted to fix my MAP sensor, but when I removed it, it was burned out. While reinstalling, I damaged the threading on one of the two bolts that attach it to the manifold, as well as the sensor’s o-ring. Now, it’s held in place by one bolt and the MAP sensor’s own fit. Since I didn’t have diagrams back then, I haven’t gotten around to fixing the MAP sensor cables yet. From what I know, the car should still run without misfires within a certain RPM range, even without the MAP sensor. I live in a tropical climate (27–35°C / 80.6–95°F), if that’s relevant.

I’ve attached the allscan from my car. The only new code since replacing the aftermarket coil is the ECM communication error; all other codes were present before.

Thursday,07,November,2024,17:37:37:29321
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 24.7.1.0 (x64)  HEX-V2 CB: 0.4643.5
Data version: 20240919 DS356.3
www.Ross-Tech.com


VIN: 3VWSV29M54M029604   License Plate:


Chassis Type: 9M (9M - VW Jetta IV (1998 > 2014))
Scan: 01 02 03 08 09 15 16 17 19 22 29 35 36 37 39 46 47 55 56 57
          75 76
 
VIN: 3VWSV29M54M029604   Mileage: 369740km-229745miles
-------------------------------------------------------------------------------
Address 01: Engine        Labels: None
   Part No: 06A 906 032 NG
   Component: 2.0l DS Mexico  G05 0302
   Coding: 00031
   Shop #: WSC 00066
   VCID: 70BE08DF33B43B1AAFB-5160
   3VWSV29M54M029604     VWZ7Z0C7853722

11 Faults Found:
16492 - Manifold / Barometric Pressure Sensor (G71) / (F96)
            P0108 - 35-00 - Signal too High
16497 - Intake Air Temp. Sensor (G42)
            P0113 - 35-00 - Signal too High
18057 - Powertrain Data Bus
            P1649 - 35-00 - Missing Message from ABS Controller
16684 - Random/Multiple Cylinder Misfire Detected
            P0300 - 35-10 -  - Intermittent
16688 - Cylinder 4
            P0304 - 35-10 - Misfire Detected - Intermittent
16686 - Cylinder 2
            P0302 - 35-10 - Misfire Detected - Intermittent
19481 - Angle Sensor 1 for Throttle Drive 2 (G297)
            P3025 - 35-10 - Implausible Signal - Intermittent
17579 - Angle Sensor 2 for Throttle Actuator (G188) Implausible Signal
            P1171 - 35-10 -  - Intermittent
16685 - Cylinder 1
            P0301 - 35-10 - Misfire Detected - Intermittent
17764 - Cylinder 1 Ignition Circuit
            P1356 - 35-00 - Short to Plus
18010 - Power Supply Terminal 30
            P1602 - 35-10 - Voltage too Low - Intermittent
Readiness: 0010 0101

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 6Q0-909-605-VW5.lbl
   Part No: 1C0 909 605 A
   Component: 23 AIRBAG VW51 02   0008
   Coding: 12851
   Shop #: WSC 00066
   VCID: 221A3297ADD8D98A69F-5140

1 Fault Found:
00655 - Seat Belt Tensioner Igniter; Passenger Side (N154)
            32-10 - Resistance Too High - Intermittent

-------------------------------------------------------------------------------
Address 17: Instruments        Labels: 1J0-920-xx5-17.lbl
   Part No: 1J5 920 806 J
   Component: KOMBI+WEGFAHRSP VDO V52
   Coding: 15332
   Shop #: WSC 00222
   VCID: 3334C7D302224002929-5140
   3VWSV29M54M029604     VWZ7Z0C7853722

4 Faults Found:
01314 - Engine Control Module
            49-10 - No Communications - Intermittent
01316 - ABS Control Module
            49-00 - No Communications
01315 - Transmission Control Module
            49-00 - No Communications
01304 - Radio
            49-00 - No Communications

-------------------------------------------------------------------------------
Address 19: CAN Gateway        Labels: 6N0-909-901-19.clb
   Part No: 6N0 909 901
   Component: Gateway K<->CAN    0001
   Coding: 00006
   Shop #: WSC 00066
   VCID: 70BE08DF33B43B1AAFB-5140

5 Faults Found:
01314 - Engine Control Module
            49-10 - No Communications - Intermittent
01316 - ABS Control Module
            49-00 - No Communications
01315 - Transmission Control Module
            49-00 - No Communications
01304 - Radio
            49-00 - No Communications
01332 - Door Control Module; Passenger Side (J387)
            49-10 - No Communications - Intermittent

-------------------------------------------------------------------------------
Address 46: Central Conv.        Labels: 1C0-959-799.lbl
   Part No: 1C0 959 799 C
   Component: BP Komfortgerát HLO 0003
   Coding: 00258
   Shop #: WSC 00066
   VCID: 372CF3C3165AAC22AE1-4B1E

   Subsystem 1 - Part No: 1C1959801A
   Component: 1H Tõrsteuer.FS KLO 0009

   Subsystem 2 - Part No: 1C1959802A
   Component: 1H Tõrsteuer.BF KLO 0004

   Subsystem 3 - Part No: 1C0959811A
   Component: BP Tõrsteuer.HL KLO 0202

   Subsystem 4 - Part No: 1C0959812A
   Component: BP Tõrsteuer.HR KLO 0202

9 Faults Found:
00932 - Electric Window Motor; Drivers Side (V147)
            62-10 - No or Incorrect Adjustment - Intermittent
00928 - Locking Module for Central Locking; Front Driver Side (F220)
            27-00 - Implausible Signal
00943 - Heated Exterior Mirror; Driver Side (Z4)
            35-10 - - - Intermittent
00933 - Electric Window Motor; Passenger Side (V148)
            62-10 - No or Incorrect Adjustment - Intermittent
00929 - Locking Module for Central Locking; Front Passenger Side (F221)
            27-00 - Implausible Signal
00944 - Heated Exterior Mirror; Passenger Side (Z5)
            35-10 - - - Intermittent
01333 - Door Control Module; Rear Left (J388)
            37-00 - Faulty
00930 - Locking Module for Central Locking; Rear Left (F222)
            27-00 - Implausible Signal
01334 - Door Control Module; Rear Right (J389)
            37-00 - Faulty

End----(Elapsed Time: 05:41, VBatt start/end: 11.9V/11.9V. VIgn 11.7V)-----

 

[Bruce]

A great first post! Thank you for your efforts...

If this were mine to chase, I would be concerned with the manifold/barometric pressure and the air temp.. because both affect the calculations for the fuel mixture..

To see what's what, I would want to view the fuel trims to see if they are even close to normal. I suspect they are not.

My problem is that I do not do this work - the things I know I learn by reading the forum and through interaction with our staff.. So, my comments are meant to stimulate other thoughts rather than offer a fix.

Hang tight, I am sure others will show here to offer next step type advice. I don't want to give that owing to my fear that I will make more headaches for you than you are already experiencing.

By the way, did you get the wiring diagram for your car? See the how to at the top of the page in the blue bar for a listing of How To get a wiring diagram. I think you are going to need it.

 

[Uwe]

2004 Jetta A4

I hate to be a curmudgeon, but the "A3", "A4", type terminology was deprecated almost 25 years ago when Audi introduced car models using those designations. I've tweaked the thread title to use the less confusing "Mk" designation.

-Uwe-

 

[Hubaro]

A great first post! Thank you for your efforts...

If this were mine to chase, I would be concerned with the manifold/barometric pressure and the air temp.. because both affect the calculations for the fuel mixture..

To see what's what, I would want to view the fuel trims to see if they are even close to normal. I suspect they are not.

My problem is that I do not do this work - the things I know I learn by reading the forum and through interaction with our staff.. So, my comments are meant to stimulate other thoughts rather than offer a fix.

Hang tight, I am sure others will show here to offer next step type advice. I don't want to give that owing to my fear that I will make more headaches for you than you are already experiencing.

By the way, did you get the wiring diagram for your car? See the how to at the top of the page in the blue bar for a listing of How To get a wiring diagram. I think you are going to need it.

Hi Bruce and Uwe, thank you for the replies.

I have Elsawin installed with the electrical diagrams for my cars. Currently, I’m experiencing a persistent misfire every time I start the car, regardless of whether I press the accelerator or not. I believe this issue began when my aftermarket ignition coil cracked. Previously, even though my MAP sensor was faulty (an issue revealed by a free OBD scan), all cylinders would still fire correctly as long as I didn’t press the accelerator too hard.

Here's the sequence of replacements and symptoms:

1. Purchased the car and took it to the mechanic for multiple repairs (head gasket, refrigerant tank, timing belt, etc.).
2. Took it to an auto electrician to fix a misfire. He replaced the ignition coil with a low-cost aftermarket part.
3. The new coil's outlets A and D failed, so I purchased another low-cost aftermarket coil. Short, spontaneous misfires (10–15 seconds) started occurring without clear input from my side.
4. Attempted to repair the MAP sensor but damaged the O-ring and one of the manifold's bolting threads.
5. The ignition coil cracked, leading to a persistent misfire on all cylinders.
6. Replaced the cheap aftermarket ignition coil, spark plug wires, and spark plugs with original BOSCH parts. However, the constant misfire remains.

Also I checked the grounding in the ignition coil 4pin connector, according to elsawin it's grounded under the wind screen in the plenum chamber, but I have no current means of removing the wiper arms so I checked the ground resistance from the T4 pin to the battery negative and it displays 0.6 ohms which according to the internet is too high so I also have this issue (among many others) to fix.

Also, I edited my original post to reflect Uwe's modification (Jetta A4 to Jetta MK4).

Thanks

 

[Dr Sheldon]

16492 - Manifold / Barometric Pressure Sensor (G71) / (F96)
P0108 - 35-00 - Signal too High
16497 - Intake Air Temp. Sensor (G42)
P0113 - 35-00 - Signal too High

19481 - Angle Sensor 1 for Throttle Drive 2 (G297)
P3025 - 35-10 - Implausible Signal - Intermittent
17579 - Angle Sensor 2 for Throttle Actuator (G188) Implausible Signal
P1171 - 35-10 - - Intermittent

All that needs to be fixed first !!

As Bruce has said - What are your fuel trims ?? LTFT ? STFT ?

For now stop chasing the Misfires - You maybe barking up the wrong tree - Quite likely the misfires are a consequence and not the root cause !

From what I know, the car should still run without misfires within a certain RPM range, even without the MAP sensor. I live in a tropical climate (27–35°C / 80.6–95°F), if that’s relevant.

Not relevant - Fix it properly !!

I checked the ground resistance from the T4 pin to the battery negative and it displays 0.6 ohms which according to the internet is too high.

Resistance testing a wire is a pretty poor test method - Useless !! You are better of with Volt Drop and Load Testing the wires !!

displays 0.6 ohms which according to the internet is too high

We are not taking into account the leads on your meter so ..........

 

[Hubaro]

All that needs to be fixed first !!

As Bruce has said - What are your fuel trims ?? LTFT ? STFT ?

For now stop chasing the Misfires - You maybe barking up the wrong tree - Quite likely the misfires are a consequence and not the root cause !


Not relevant - Fix it properly !!



Resistance testing a wire is a pretty poor test method - Useless !! You are better of with Volt Drop and Load Testing the wires !!


We are not taking into account the leads on your meter so ..........

Hi Dr. Sheldon,
Thank you for your help.
I’ll start by looking into repairs for these issues and gathering fuel trim data. Do you recommend that I post the data now along with my current issues, or should I first try to resolve the MAP and angle sensor problems? Also, could you advise on the location of the G297 sensor mentioned in the scan? I’ve had trouble locating it in the wiring diagrams; I was able to find the diagram for the G188 sensor for the throttle body, but the G297 sensor doesn’t appear anywhere. In elsawin, the only throttle body sensors i've found are the following:

G186 - Throttle Control (electronic throttle actuator)
G187 - Angle Sensor 1 for Throttle Control (electronic throttle actuator)
G188 - Angle Sensor 2 for Throttle Control (electronic throttle actuator)

Thanks again!

 

[Dr Sheldon]

No point at looking at fuel trims on an engine with other faults present - Those need resolving !!

As for G297 ?

What I do know is that the throttle body will have an actuator and 2 position sensors - they all do !!

I think G297 points to a sensor in a Engine with 2 throttle bodies -- Which yours does not have !!


I would treat that as a misprint for now - just tread carefully !!

 

[Uwe]

Also, could you advise on the location of the G297 sensor mentioned in the scan? I’ve had trouble locating it in the wiring diagrams; I was able to find the diagram for the G188 sensor for the throttle body,

VW plays stupid games with the designations for for sensors and actuators at times. Your throttle body has two position sensors for redundancy. Both have "implausible signal -- intermittent" type faults. Chance are the problem isn't the sensors themselves, but something they have in common.

-Uwe-