Polo 9N3 1.4 PD DPF: Engine Won't Start

Hey everyone!!!


I have a question regarding the evaluation of measured value blocks for the 1.4L PD/DPF (BMS) system...


Perhaps you can help me. This is a driving school car that's used all day, and it's mostly driven at low RPMs! Mileage: 170,000 km.



Problem: Vehicle has no power.

The engine is running unevenly, and it's producing a lot of black smoke, especially under load.

High consumption.

Lambda, maximum value, fully saturated.

AGR is immediately and fully activated (100%) under load.

Turbo, intercooler, and valve timing are all okay.

I have the measurement data for both idle and load conditions.


I removed and cleaned the AGR valve (it was heavily carbonized, and it had already been replaced a year and 70,000 km ago due to carbon buildup).
Exhaust Gas Recirculation (EGR) valve diagnosis performed while the component was removed: OK. Reinstalled the valve, but the problem persists.


My question now is, who can analyze MWB data and identify correlations... or has anyone encountered a similar case before?


The fact is, it's constantly running at full throttle... I suspect it's either the EGR valve or the mass airflow sensor... but I don't want to just guess...

Tip:
- Check the charge air cooler for leaks.
- Post measurement data.
- Please adhere to the forum rules.

Regards,
Guste.

Hello Gauls!

Here's a preliminary note: In this post, we don't expect every sentence to be confirmed with "3x Return" or, alternatively, to end with 3-4 exclamation or question marks. *smart-aleck*

If you already have those log files, why don't you upload them directly to our "Upload" section here?

"Lambda at the maximum emission limit" is displayed in the measured values (completely outrageous, seriously!).

In the crystal ball, I'm excluding your description of "100% AGR at load." I think you might be confusing the control ratios of the valves for AGR (Abgasrückführung) and VTG (Variable Turbine Geometry)?
Alternatively (seriously, this is crazy!), someone might have been working on it before, and they incorrectly installed the hoses or electrical connections of the aforementioned valves .

Okay, please upload the logs you mentioned, so we can better assist you.

(totally awesome, dude!) Greetings from Munich!

EDIT: *zefix* Guste was faster - again today! ...am I getting old? *g*

1 error detected.






08598 P2196 000

Lambda sensor 1, bank 1 - mixture too rich.

sporadically





Environmental conditions:



Default values:




Date.

--.--.----


Time.

--:--:--


Mileage.

0167280


Priority.

2


Error frequency.

1.


Lost counter.

-







Measurement values:




Value 1.

1990 /min


Value 2.

84 km/h


Value 3.

69


Value: 4

39.6 °C


Value: 5

1040 mbar


Value: 6

0.584 V


Value: 7

0.03
Measurement.
Result.
Set point.


Engine speed.
900 per minute.
790 - 1000 revolutions per minute.


Injection amount.
4.7 mg/H
3 - 9 mg/dose.


Funding duration (target).
6.8 kW
3 - 9 °KW


Coolant temperature.
63.9 °C
> 75 °C


Engine speed.
880 /min
790 - 1000 revolutions per minute.


Throttle position sensor.
0.0%
> 0%


Operating states.
0 01 0
00000 - 11111


Coolant temperature.
63.9 °C
> 75 °C


Engine speed.
880 /min
790 - 1000 revolutions per minute.


Exhaust gas recirculation (EGR) should be...
250 mg/hour.
220 - 350 mg/dose.


Air mass is...
555 mg/H
220 - 350 mg/dose.


Exhaust gas recirculation duty cycle.
100%
20 - 90%


Engine speed.
900 per minute.
790 - 1000 revolutions per minute.


Start date of funding: To be determined.
2.5° v.OT
-4.0 to -2.0 °KW


Funding duration (target).
7.2 kW
3 - 9 °KW


Rotation angle.
-2.3 °KW
-6 - +6 °KW


Engine speed.
880 /min
810 - 1000 revolutions per minute.


Start Quantity
12.6 mg/H
7 - 19 mg/dose.


Initial synchronization.
48
000 - 128


Coolant temperature.
63.9 °C
> 75 °C


Driving speed.
0 km/h
0 - 300 km/h


Switch positions.
00001100
00000000 - 11111111


Throttle position sensor.
0 km/h
> 0.0%


FGR status not applicable to vehicles carrying ADR goods.
00000010
00000000 - 11111111


Air mass is...
550 mg/hour.
260 - 350 mg per injection.


Atmospheric pressure.
989 millibars.
900 - 1100 millibars.


Boost pressure is...
1009 millibars.
900 - 1150 millibars.


Throttle position sensor.
0.0%
> 0.0%


Engine speed.
900 per minute.
790 - 1000 revolutions per minute.


Target boost pressure.
1091 millibars.
900 - 1150 millibars.


Boost pressure is...
1009 millibars.
900 - 1150 millibars.


Valve lift ratio, boost pressure.
79%
40 - 90%


Throttle valve control, fuel injection quantity, cylinder 1.
0.05 mg/H
-2.8 to -2.8 mg/dose


Throttle valve control, fuel injection quantity, cylinder 2.
-0.24 mg/H
-2.8 to -2.8 mg/dose


Throttle valve control, fuel injection quantity, cylinder 3.
0.14 mg/H
-2.8 to -2.8 mg/dose


Throttle valve control, fuel injection quantity, cylinder 4.

-2.8 to -2.8 mg/dose


Solenoid valve for cylinder 1, used for traffic control.
0
< 00


"Solenoid valve for cylinder 2, used for traffic control."
0
< 00


"Solenoid valve for cylinder 3, used for holding pressure."
0
< 00


"Solenoid valve for cylinder 4, used for traffic control."

< 00


Solenoid valve switching time deviation, cylinder 1.
-38
-100 - 100


Solenoid valve switching time deviation, cylinder 2.
-40
-100 - 100


Solenoid valve, switching time deviation, cylinder 3.
-43
-100 - 100


Solenoid valve, timing deviation, cylinder 4.

-100 - 100


Pedal position sensor voltage 1 at full depression.
0.760 V
3,800 - 4,940 V


Pedal position sensor voltage 2 at full depression.
0.380 V
1.90 - 2.58 V


Sensor 1 for exhaust gas temperature, Bank 1 - G235.
306.0 °C
0 - 790 °C


Exhaust temperature in the particulate filter (simulated).
270.0 °C
0 - 600 °C


Loading coefficient.
11%
< 45%


Lambda value.
2.69



Temperature before the turbocharger.
294.0 °C



Temperature before the diesel particulate filter.
282.0 °C



Temperature after diesel particulate filter.
246.0 °C



Functional test.

Hello, please don't make the posts so long.

Check for leaks in the LD line.

Quote:

Engine speed. 880 per minute. 790 - 1000 revolutions per minute (RPM). ... Air mass. 555 mg/H

Either a counterfeit LMM (Mass Air Flow sensor) is installed (available with a Bosch logo on certain online marketplaces for scammers and those who want to be), or the air being measured is being leaked somewhere before the engine, causing a significant amount of noise.
At idle, without the EGR system, an air mass of approximately 440-480 mg/stroke is expected. If the part is completely clogged, it will likely be closer to 440 mg/stroke.

It's questionable whether the injection quantity at partial load is actually limited by the air mass in this component. Please post the VAG part number of the engine control unit.
However, the exhaust gas content is definitely too high and can already cause soot formation.

Best regards, Rainer.

Sorry about the long post!!!!

I've made some progress now!

- Intercooler system in good condition.

- Mass airflow sensor (original new part)
- Cross-exchange without modification.

-AGR valve is working.

DPF loading level: 43%, regenerated to 0% without issues. After another 10 km of constant driving in 5th gear at 3000 RPM, the loading level was already back up to 19%. Subsequently, while maintaining the same load, I observed that the lambda value was fluctuating between 2.0 and 2.7, simultaneously with the fuel injection quantity and injection duration being at their upper limits!

My conclusion is that it's possible that the injection time is extended to compensate for a lack of fuel or a pressure loss.

Power consumption of the pre-pump: 6A... OK.

Fuel pressure tandem pump, idling pressure: 4.5 bar, fixed.

Internal leak test of the pump using a test pressure of 1 bar (return closed) for 5 minutes - OK.

Fuel pressure at 3000 RPM without load is 7.2 bar, fluctuating by 0.5 bar. This value suggests that either the tandem pump is malfunctioning or the seals of the common rail injectors are faulty.

I plan to swap the tandem pump tomorrow, and if necessary, I will ultrasonically clean the PD elements and reseal them.

What do you think of my theory? Unfortunately, I don't have any new measurement data available.

What happens if you block the return flow during a pressure measurement? Will the needle jump?

With what do you actually measure the fuel pressure? I used to have a pressure gauge that would also fluctuate a lot, especially at high RPMs. Eventually, I bought one filled with glycerin, and it got much better. I just want to say that this kind of problem can sometimes be caused by the gauge itself before you start replacing injectors.

Apart from the slight vibration, the pressure is actually quite good. MWB 23 also shows something similar.

Error found... purely mechanical!
I can and want to post, but I don't want to do it publicly!!!! .....6000 euros of damage.

mechanics77 wrote:

...I can and want to post, but I don't want to do that publicly!!!!...

It's a shame, as this won't help other people seeking assistance. It would be nice to know what might cause something like that.

Okay... externally, there is information suggesting that, due to quality issues, some 1.9L PD engines may experience significant camshaft wear, leading to cracks or breakage of the hydraulic lifters. Furthermore, worn camshafts can extend the injection time. In these cases, the camshaft and hydraulic lifters need to be replaced. This often occurs in taxis, driving school vehicles, or vehicles driven frequently in short-distance traffic.

Internally, all PD (Pumpe-Düse) vehicles are affected, ranging from the 3B 1.9L to the 1J, 3C, 1T, and up to the 9N 1.4L engines.

In my specific case, it's a 9N-1.4L PD model from 2008 with 160,000 km. The camshaft is severely worn, the hydraulic lifters are broken, and there are signs of wear on the ball joint connecting the PDE to the adjustment screw. This has damaged the DPF (due to oil contamination), the EGR valve is clogged with carbon deposits, and there are turbocharger particles from the broken lifter. The guide in the cylinder head is also damaged due to the broken lifter.

Result: Replace the cylinder head with camshaft, DPF, and turbo... Clean the EGR... and this after two and a half years and 160,000 km.

Thank you for the information, even though it was late.

Hmmm, so far I'm at €6300... after two and a half years...

What does your price include?
Why are you hesitant to express your opinion when you're going to pay for it anyway? What kind of oil was used? I've seen several 1.9 engines with camshafts that had significantly more than double the mileage and still looked good. Surely, even a driving school car idles for hours, and you only make money when the car is moving, right?

Cylinder head damaged by a broken hydraulic lifter in its bore.

Clogged diesel particulate filter and a stuck EGR valve due to a constantly rich fuel mixture!

Soot accumulation, approximately 1 cm thick.

Turbocharger damage cannot be ruled out due to the broken hydraulic lifter, especially considering the 2-year warranty on this repair!