Hi car not running right.

 

2008 Octavia 2 1.9 PD BXE

Hi car running poorly despite new turbo

Down on power - only really obvious once fully warmed up.

Most apparent over 2000 rpm, at which point power delivery is not smooth - very jerky.

A bit more of a smokey diesel smell than it used to have.

MPG has dropped by about 10 mpg

This car does not have a DPF - never did.

It has been converted to SMF.

Has had a reconditioned turbo - prior to this was even worse.

EGR valve cleaned, new MAF sensor, new fuel filter.

Torsion value is 0.5 degrees

It all started to go wrong after a service and cam belt change - may or may not be related.

 

Neither self or garages have been able to get to bottom of it.

Aware it's a big ask, but if anyone with more experience of interpreting VCDS data could cast an eye over the log below to see if they can see anything untoward it would be much appreciated.

 

Thanks

______________________________________________________

Group 001: Injection Quantity

  819 /min  Engine Speed (G28)

  6.9 mg/str  Injection Quantity 

  7.7°KW  Injection Duration (specified)

  62.1°C  Coolant Temperature (G62)

 

Group 002: Idle Speed

  840 /min  Engine Speed (G28)

  0.0 %  Accel. Pedal Pos. Sensor 1 (G79)

   0 01  1  Operation Status 

  62.1°C  Coolant Temperature (G62)

 

Group 003: Exhaust Gas Recirculation (EGR)

  819 /min  Engine Speed (G28)

  240.0 mg/str  Exhaust Gas Recirculat. (spec.)

  470.0 mg/str  Exhaust Gas Recirculat. (actual)

  95.5 %  Exhaust Gas Recirc. Duty Cycle

 

Group 004: Pump-Jet Valves

  819 /min  Engine Speed (G28)

  0.3 °BTDC  Injection Start (specified)

  7.7°KW  Injection Duration (specified)

  0.5°KW  Torsion Value 

 

20:53:45 Group 005: Start Conditions (last Engine Start)

  819 /min  Engine Speed (G28)

  14.8 mg/str  Start Injection Quantity

  48.0  Start Synchronisation

  63.0°C  Coolant Temperature (G62)

 

Group 006: Cruise Control System (CCS)

  0.0 km/h  Vehicle Speed (actual)

  00101100  Pedal Monitoring 

  0.0 %  Accel. Pedal Pos. Sensor 1 (G79)

  10000001  Switch Monitoring 

 

Group 007: Temperatures

  60.3°C  Fuel Temperature (G81)      

  25.2°C  Intake Air Temperature (G72)

  63.0°C  Coolant Temperature (G62)

 

Group 008: Injection Quantity Limitation I (Torque Limitation)

  819 /min  Engine Speed (G28)

  0.0 Nm  Torque Request (Driver)

  161.0 Nm  Torque Limitation 

  141.5 Nm  Smoke Limitation 

 

Group 009: Injection Quantity Limitation II (Torque Limitation)

  819 /min  Engine Speed (G28)

  -1280.0 Nm  Torque Request (Cruise Control)

     Transmission Limitiation

  141.5 Nm  Torque Restriction 

 

Group 010: Charge Pressure Control

  450.0 mg/str  Mass Air Flow (actual)

  1020.0 mbar  Atmospheric Pressure

  897.6 mbar  Boost Pressure (actual)

  0.0 %  Accel. Pedal Pos. Sensor 1 (G79)

 

Group 011: Charge Pressure Control

  819 /min  Engine Speed (G28)

  1091.4 mbar  Boost Pressure (specified)

  897.6 mbar  Boost Pressure (actual)

  83.6 %  Charge Pressure Control Duty Cycle

 

Group 012: Glow Plugs

  11111111  Glow Status 

  0.00 s  Pre-Glow Period 

  14.36 V  Supply Voltage (Terminal 30)

  63.0°C  Coolant Temperature (G62)

 

Group 013: Idle Stabilization (Injection Quantity Deviation)

  -0.33 mg/str  Injection Quantity Deviation Cyl. 1

  -0.19 mg/str  Injection Quantity Deviation Cyl. 2

  0.19 mg/str  Injection Quantity Deviation Cyl. 3

  0.35 mg/str  Injection Quantity Deviation Cyl. 4

 

Group 015: Fuel Consumption

  819 /min  Engine Speed (G28)

  46.4 Nm  Engine Torque 

  0.80 l/h  Fuel Consumption 

  0.0 Nm  Torque Request (Driver)

 

Group 016: Auxiliary Heating

  36.1 %  Generator Load 

  11000000  Bin. Bits 

        00  Bin. Bits 

  14.36 V  Supply Voltage (Terminal 30)

 

Group 017: Readiness Code (EOBD)

  00000000  CARB Mode 01 DATA A

  00000110  CARB Mode 01 DATA B

  10000000  CARB Mode 01 DATA C

  00000000  CARB Mode 01 DATA D

 

Group 018: Injector Status

  0.0  Injector Status Cylinder 1

  0.0  Injector Status Cylinder 2

  0.0  Injector Status Cylinder 3

  0.0  Injector Status Cylinder 4

   

Group 020: Injection Quantity Limitation (from ABS)

  819 /min  Engine Speed (G28)

  46.4 Nm  Engine Torque 

  1270.0 Nm  ASR Limitation 

  -1280.0 Nm  MSR Limitation 

 

Group 021: CAN-Databus Status (Powertrain)

  00000000  Engine Electronics 

     Transmission Electronics

  00000000  Brake Electronics 

  00000100  Brake Electronics (ESP)

 

Group 022: Shut-Off Status

  0.0  Shut-Off Status Cruise Control

  0.0  Switch Monitoring Cruise Control

  0.0  Shut-Off Status Charge Pressure

  0.0  Shut-Off Status Climate Control

 

20:55:44 Group 023: Injector Switch Time Deviation

  1.0  Switch Time Deviat. Cylinder 1

  10.0  Switch Time Deviat. Cylinder 2

  1.0  Switch Time Deviat. Cylinder 3

  -16.0  Switch Time Deviat. Cylinder 4

 

20:55:44 Group 025

  819 /min  Engine Speed (G28)

         0  Bin. Bits 

  4.0  (no units) 

  1.0  (no units) 

 

Group 026: Checksum

  BC82  Checksum 

 

 

Group 028: Accelerator Pedal Position Sensor

  0.760 V  Accel. Pedal Pos. Sensor 1 (G79)

  0.380 V  Accel. Pedal Pos. Sensor 2 (G185)

   0 01  1  Operation Status 

  0.0 %  Accel. Pedal Pos. Sensor 1 (G79)

 

 

Group 029: Temperature and Oil Level Sensor (TOG)

  60.3°C  Oil Temperature 

  30.0 mm  Oil Level 

  18.0  Wear Index 

  58.0  Soot Index 

 

Group 046

  100.6 %  Duty Cycle     

  95.5 %  Duty Cycle 

 

Group 051: Engine Speed Recognition

  819 /min  Engine Speed 

  399 /min  Camshaft Speed 

  48.0  Start Synchronisation

  01010000  Shut-Off Status Injection Sequence

 

Group 055

  0.0  (no units) 

  0.0  (no units) 

  00100000  Bin. Bits 

  00100000  Bin. Bits 

 

Group 056

  00100000  Bin. Bits 

  00100000  Bin. Bits 

  00100000  Bin. Bits 

  0xFF00  Hex Value 

 

Group 062: Engine Cooling (Temperatures)

  67.5°C  Coolant Temperat. Engine Output

  16.2°C  Coolant Temperat. Cooler Output

  8.1°C  Ambient Temperature

  26.1°C  Intake Air Temperature

 

Group 063: Engine Cooling (Climate Control)

  7.81 bar  Refrigerant Pressure

  3.0 Nm  Load Torque 

     Cooling Request 

  0.0  Shut-Off Status Climate Control

 

Group 064: Engine Cooling

  68.4°C  Coolant Temperature (G62)

  16.2°C  Coolant Temperat. Cooler Output

  17.3 %  Coolant Fan 1 Duty Cycle

     

Group 087: EOBD

  11111111  Bin. Bits 

  11111111  Bin. Bits 

  11001111  Bin. Bits 

       

Group 089

  00000000  Bin. Bits 

  00000110  Bin. Bits 

  10000000  Bin. Bits 

  00000000  Bin. Bits 

 

Group 090: EOBD/OBD-2 Exhaust Gas Recirculation (EGR) I

  819 /min  Engine Speed (G28)

  7.1 mg/str  Injection Quantity 

  240.0 mg/str  Exhaust Gas Recirculat. (spec.)

  00000000  Status Control Deviation

 

Group 091

  323.85  (no units) 

  -326.40  (no units) 

  240.0 mg/str  Mass Air / Rev. 

  -201.45  (no units) 

 

Group 093

  00000000  Bin. Bits 

  0.90  (no units) 

  11.38 g/s  Mass Flow 

  11.38 g/s  Mass Flow 

 

 

 

Hi

 

Had been discounting the possibility of a MAF sensor fault as it had been replaced and it is not showing as a fault on VCDS. It has however been suggested to me that faults in new MAF sensors are a possibility and that they do not always show up on VCDS scan.

 

Does the running OK (but not quite 100%) when cold and at low revs but hesitant and down on power at higher temperatures (particularly noticeable over 2000 rpm), tie in with a faulty MAF sensor?

 

Thanks 

What does it run like if you disconnect the MAF.

 

It is possible for a MAF to be faulty, but still provide meaningful but wrong data to the ECU. Disconnecting it will force the car to run a default program get you home type mode.

 

As its a PD engine, if anything moves when replacing the cambelt then injectors may not be injecting fuel at the correct moment and could need to have their timing altered.

 

http://www.myturbodiesel.com/wiki/camshaft-timing-torsion-value-adjustment-on-vw-and-audi-pd-tdi-engines/

Edited 22 April, 201610 yr by mannyo

was the MAF replaced with an OEM part? or cheapo knock off?

Shouldn't cam speed be half of crank ? group 51 looks slightly out to me ..? Who changed the belt? 0.8l per hour consumption sounds a bit high as well.

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Wonder why it's recirculating twice as much exhaust gas as it should be? Or why it thinks that's what's happening.

Wonder why it's recirculating twice as much exhaust gas as it should be? Or why it thinks that's what's happening.

Thanks, that's a good question right enough. Can anyone out there say what this suggests to be the cause? Also as Wino's reply hints at - Is it really recirculating twice as much as exhaust gas as it should or does it just think it is? Is the 'actual' reading really an actual reading?

 

In another post 'Exhaust Gas Recirculation. Duty Cycle' 10 04 16 I plotted actual and specified against RPM while accelerating. There is a similar magnitude of deviation - although not so much in % terms as both figures are higher. Was not sure how bad this is as was not expecting a perfect match in this non steady state condition.

 

Thanks again

Shouldn't cam speed be half of crank ? group 51 looks slightly out to me ..? 

Thanks,

Yes no doubt about that, if crank speed is 819 rpm cam speed has to be 409.5 rpm so would expect to see 409 or 410. Will investigate but I think that this and several other output values are not continuously variable but jump in steps. The 819 rpm seems to appear quite often in postings but not 818 or 820. 

Wonder why it's recirculating twice as much exhaust gas as it should be? Or why it thinks that's what's happening.

 

  240.0 mg/str  Exhaust Gas Recirculat. (spec.)

  470.0 mg/str  Exhaust Gas Recirculat. (actual)

 

Might be on to something there. Elsewhere on the wonderful interweb there is a suggestion that '470.0 mg/str  Exhaust Gas Recirculat. (actual)'. Is a default figure that is reverted to in the event of a failed MAF sensor.

Thanks,

Yes no doubt about that, if crank speed is 819 rpm cam speed has to be 409.5 rpm so would expect to see 409 or 410. Will investigate but I think that this and several other output values are not continuously variable but jump in steps. The 819 rpm seems to appear quite often in postings but not 818 or 820. 

 

I don't think VCDS can read two data values at once, instead there will be a short delay between the two giving the engine speed chance to change hence the small difference. When I was logging DPF data on my CR140 there was up to 0.2s between measurements...

 

Rather than just given static data, it might be better to log a 5 minute period or even a 20 minute drive. After which, VCDS will give you a CSV file full of data you can graph to spot patterns on or compare to cars that are running well.

Had a vw t5 tdi common rail in during the week . Engine workshop coming up on dashboard. Checked with vcds. Fault was cam and crank incorrect correlation. In measured value's was getting very similar reading as yours on this log. Don't know end result yet as it's booked in next couple of weeks for me to check valve timing.

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Rather than just given static data, it might be better to log a 5 minute period or even a 20 minute drive. After which, VCDS will give you a CSV file full of data you can graph to spot patterns on or compare to cars that are running well.

Thanks. Yes have tried some extended monitoring of some blocks. Generated a massive amount of data - was going to plot in Excel but it was going to take ages even to select the data to create graph. How do you go bout reducing the sampling rate?

 

Thanks again

Had a vw t5 tdi common rail in during the week . Engine workshop coming up on dashboard. Checked with vcds. Fault was cam and crank incorrect correlation. In measured value's was getting very similar reading as yours on this log. Don't know end result yet as it's booked in next couple of weeks for me to check valve timing.

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Thanks.

 

Are you still getting a sensible torsion value?

 

Strange thing with mine is not getting fault codes or dash warning lights.

Have not really looked much further than cam and crank speeds. This t5 tdi is common rail so think it's a bit more advanced on the fault code side.

Another thing to check on yours is n75 and hose block. I had one a few year's back. The owner had a turbo fitted and it still had no power by another garage. I found that there was a corroded pin for the live for n75. This pin was in a multi plug under the air filter housing and above the gearbox. Have also seen a lot of broken wires above the gearbox in the past in the loom.

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Thanks. Yes have tried some extended monitoring of some blocks. Generated a massive amount of data - was going to plot in Excel but it was going to take ages even to select the data to create graph. How do you go bout reducing the sampling rate?

Thanks again

Even an hour's drive plotting a 30k+ data points was instant using excel for me. If you drop me the csv file from VCDS in a PM I should be able to plot it for you :-)

Even an hour's drive plotting a 30k+ data points was instant using excel for me. If you drop me the csv file from VCDS in a PM I should be able to plot it for you :-)

Many thanks for the kind offer. I now see how to use Excel short cuts to select bulk data - I had been using click and drag selection which was taking for ever.

 

So have now been able to plot larger data files.

 

Attachment is temperature sensors plot (Approx 75000 data points) taken with car idling - it took a lot longer for car to get up to full temp than I had expected but don't think there is anything wrong with this. Outside temperature from car sensor was 8.5 degrees C. Should say car was not quite fully cold at start.

 

Thanks again.

Edited 23 April, 201610 yr by Octy0GG

Hi

 

Took car for a run - starting from almost cold.

Very beginning of plot includes starting engine.

 

Would appreciate any thoughts on attached plot of specified and actual egr.

 

One thing that puzzles me is high EGR under full acceleration - thought engine would be allowed luxury of maximum oxygen for this.

 

Thanks

Edited 24 April, 201610 yr by Octy0GG

Do a wot test of group 3 from 2000 rpm to 4000 rpm. Do the same for group 8 and group 11. Do 3 logs in total and post them up.

Don't bother looking st the actual vs requested for the MAF just do the above and we'll be able to see if the smoke map (MAF sensor) is holding the fuel back (group 8)

Do a wot test of group 3 from 2000 rpm to 4000 rpm. Do the same for group 8 and group 11. Do 3 logs in total and post them up.

Don't bother looking st the actual vs requested for the MAF just do the above and we'll be able to see if the smoke map (MAF sensor) is holding the fuel back (group 8)

 

Log attached.

 

Got very rough - surging and missing as it neared 4000rpm

 

Any light which anyone can shed on log most welcome.

 

Many Thanks

SUNDAY 24 4 16 Blocks 3 8 11.csv

Edited 24 April, 201610 yr by Octy0GG

Hi 

 

Have converted above log into plots, included here.

MAF sensor is fine and is not limiting fuel. Boost is dropping off below requested at the high 3000rpm

MAF sensor is fine and is not limiting fuel. Boost is dropping off below requested at the high 3000rpm

Thanks.

 

Turbo is a recently fitted reconditioned unit, so should be OK.

I have tested the vacuum pipe going from the relay block to the turbo and it holds vacuum.

Using a hand operated vacuum pump I have confirmed that the EGR valve opens and closes - realise this is not exactly the same as operation when engine running.

The difference between actual and requested boost only really starts to be significant after 3500rpm. The poor performance starts way bellow this.

Should also say that I have since tried running with MAF sensor disconnected (obviously the Log and plots are with MAF sensor connected) initially thought this brought an improvement but after a few more runs it became less conclusive to the point where I would now say no real difference.

 

Anyone know what the main suspect(s) are now?

 

Thanks again

As per one of the previous posts above - have you checked the N75 (boost pressure regulation sensor) and the associated vacuum pipes?

A split diaphragm in the N75 or a small tear in one of the vacuum pipes can cause similar issues, although this normally throws up a high or low boost pressure DTC.

As per one of the previous posts above - have you checked the N75 (boost pressure regulation sensor) and the associated vacuum pipes?

A split diaphragm in the N75 or a small tear in one of the vacuum pipes can cause similar issues, although this normally throws up a high or low boost pressure DTC.

Thanks

 

Mk5 Platform car so am I correct in saying N75 is now part of solenoid valve block?

 

P6 on the  solenoid valve block goes down the back of the engine to the turbo, have checked this pipe with a vacuum pump to 20inHg - Holds this fine. Anything else I can check in relation to this?

 

Alternatively of course have I got this wrong? is there a separate N75 valve lurking somewhere that I haven't found.

 

Thanks again.

You are correct N75 is combined in the solenoid valve block.

Also try checking the pins connectors to / from the solenoid valve block.