# 2007 2.5L jetta-running rough! Please help



## memoksp1 (Jul 30, 2020)

Codes show it's running lean. When I cold start my car the first 10 seconds run really rough, rpms drop up and down and half the time the car dies. Once it gets going though it starts running really good. We have replaced pcv valve cover, replaced purge solenoid, Replaced the MAF sensor, did a smoke test and found no leaks in the air system and also pulled and cleaned the throttle body.

VCDS log and fault codes below. Any suggestions?


VCDS 031 032 measuring block log
Address 01: Engine (07K 906 032 T)

17:19:00 Group 031
0.984 Lambda Sensor Current Value
1.000 Lambda Sensor Specified Value


17:19:00 Group 032
5.1 % Lambda (Idle) Self-Adaptation
20.3 % Lambda (Partial) Self-Adaptation



VCDS Fault codes
Thursday,30,July,2020,17:17:34:54968
VCDS Version: Release 20.4.1 (x64) Running on Windows 10 x64


Address 01: Engine Labels: 06A-906-032-BGP.lbl
Control Module Part Number: 07K 906 032 T HW: 07K 906 032 Q
Component and/or Version: 2.5l R5/4V G 9653
Software Coding: 0000001
Work Shop Code: WSC 00066 000 00000
VCID: 3A2D34467052F25B5DF-806E
6 Faults Found:

000369 - Fuel Trim; Bank 1
P0171 - 001 - System Too Lean - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 316959 km
Time Indication: 0
Date: 2000.00.00
Time: 00:43:21

Freeze Frame:
RPM: 2694 /min
Load: 38.0 %
Speed: 100.0 km/h
Temperature: 99.0°C
Temperature: 45.0°C
Absolute Pres.: 980.0 mbar
Voltage: 14.224 V

001290 - Cold Start Idle Air Control System
P050A - 002 - Malfunction - MIL ON
Freeze Frame:
Fault Status: 11100010
Fault Priority: 0
Fault Frequency: 18
Reset counter: 255
Mileage: 317096 km
Time Indication: 0
Date: 2000.00.00
Time: 11:44:52

Freeze Frame:
RPM: 1263 /min
Load: 74.9 %
Speed: 0.0 km/h
Temperature: 30.0°C
Temperature: 28.0°C
Absolute Pres.: 980.0 mbar
Voltage: 13.970 V

000768 - Random/Multiple Cylinder Misfire Detected
P0300 - 008 - - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10101000
Fault Priority: 0
Fault Frequency: 4
Reset counter: 255
Mileage: 317733 km
Time Indication: 0
Date: 2000.00.00
Time: 23:21:19

Freeze Frame:
RPM: 1426 /min
Load: 76.4 %
Speed: 0.0 km/h
Temperature: 20.0°C
Temperature: 32.0°C
Absolute Pres.: 980.0 mbar
Voltage: 14.097 V

000770 - Cylinder 2
P0302 - 008 - Misfire Detected - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10101000
Fault Priority: 0
Fault Frequency: 3
Reset counter: 255
Mileage: 317733 km
Time Indication: 0
Date: 2000.00.00
Time: 23:21:58

Freeze Frame:
RPM: 1207 /min
Load: 24.7 %
Speed: 9.0 km/h
Temperature: 29.0°C
Temperature: 33.0°C
Absolute Pres.: 980.0 mbar
Voltage: 14.351 V

000769 - Cylinder 1
P0301 - 008 - Misfire Detected - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10101000
Fault Priority: 0
Fault Frequency: 2
Reset counter: 255
Mileage: 317881 km
Time Indication: 0
Date: 2000.00.00
Time: 19:51:49

Freeze Frame:
RPM: 2334 /min
Load: 69.0 %
Speed: 19.0 km/h
Temperature: 22.0°C
Temperature: 18.0°C
Absolute Pres.: 980.0 mbar
Voltage: 14.478 V

000771 - Cylinder 3
P0303 - 008 - Misfire Detected - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10101000
Fault Priority: 0
Fault Frequency: 2
Reset counter: 255
Mileage: 317881 km
Time Indication: 0
Date: 2000.00.00
Time: 19:51:49

Freeze Frame:
RPM: 2334 /min
Load: 69.0 %
Speed: 19.0 km/h
Temperature: 22.0°C
Temperature: 18.0°C
Absolute Pres.: 980.0 mbar
Voltage: 14.478 V


Readiness: 0000 1001


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## 2.5T\/DUB (Aug 1, 2020)

I've had these issues in the past with older 2.5's and this is where I would start:

1. Fuel Filter (could be clogged)
2. Ignition Coils (switch cylinder 1 coil with cylinder 5 coil, switch cylinder 2 coil with cylinder 4 coil, if you get a misfire on cylinder 5 and 
cylinder 4 then it may be time to replace all ignition coils, if this has never been done then now is definitely the time anyway!)
3. Spark Plugs (do the same as the ignition coils, but honestly if you're going through the hassle go ahead and replace them)
4. Fuel Injectors (clogged or non-functioning)
5. Fuel Pump (OEM pumps start failing after 150,000 miles, everyone's experience is different though, but generally an 07's pump should be 
replaced anyway)


Usually misfires codes are from a lack of spark and/or fuel. You might be amazed at how much better a 2007 2.5 with run with 
fresh coils, plugs, fuel filter, and injectors. You can test the fuel pump pressure from the fuel rail, I believe you should have a 
steady 50-60psi with a proper functioning pump.


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## Aleforge (Sep 8, 2011)

I am not sure if you found out what it was yet but I had similar issues and it turned out to be a bad O2 sensor.


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## 2.5T\/DUB (Aug 1, 2020)

Aleforge said:


> I am not sure if you found out what it was yet but I had similar issues and it turned out to be a bad O2 sensor.


Agreed, could be that as well, didn't think about O2's..


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## le0n (Jun 12, 2013)

a bad bank 1 o2 sensor would cause the engine to run rich, not lean.

you're showing lean errors because you're bank 1 o2 sensor is reading more o2 than what is expected (calculated pre-throttle body (post MAF)).

in other words, you have an undetected vacuum leak.

quick test would be to clamp shut the N80 purge vacuum line leading to the rear of the vehicle and see if the idle improves.

if it does, your purge valve is faulty or may need to be cleaned (even if it is new).

if it is not the purge valve, the other culprit is a cracked intake manifold, check the stand-off posts that the air box connects to.


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## Timbert (Jul 22, 2017)

PCV is my best guess, new or not. Disconnect the hose going to the throttle body, plug the throttle body side and see how it runs. The illegal air is coming from somewhere.


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