2010 Passat 2.0 TDI - Erratic/fluctuating revs at idle

Hi all

Tried searching but could not really find anything...

Anyway, I have a 2010 Passat with 170k miles on the clock. Still going strong except for one thing - at idle the revs fluctuate and the engine shakes.

We have recently replaced all the injectors and tried another fuel pressure rail, which has not cured the problem.

Diagnostic scan shows no fault codes, but we found out that the fuel pressure was not consistent on all cylinders.

Any ideas?

When you fitted the new injectors, did you enter the new IMA codings in the injector tables?

Thanks - yes the IMA codes were entered.

We took it to a VW specialist who tried a few obvious things and made a few suggestions. None seemed to make a difference.

Premium diesel tends to improve things slightly.

Just wondered if there might be any other ideas that were missed.

Cheers

Study the high pressure pump values and other measuring block data.

is their any particular time this starts either cold or warm any black smoke at start up or at running temperature maybe a dribbling injector (faulty) you could check by the ohms reading at each injector 2 pins if you get a reading with a multimeter between 1 of these 2 pins and a reading at theout side body of injector then the injector insulation is faulty (injector gossed) Regards Mickeybo

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Originally Posted by Crasher

Study the high pressure pump values and other measuring block data.

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I think this was probably carried out when it went to the garage. Can this be done with an OBD reader? If so I can borrow one to use at home.

Quote:

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Originally Posted by mickeybo

is their any particular time this starts either cold or warm any black smoke at start up or at running temperature maybe a dribbling injector (faulty) you could check by the ohms reading at each injector 2 pins if you get a reading with a multimeter between 1 of these 2 pins and a reading at theout side body of injector then the injector insulation is faulty (injector gossed) Regards Mickeybo

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It happens at all times, from start-up and throughout a journey of any length. It doesn't seem to be affected by engine or ambient temperature.

As mentioned, we swapped all the injectors and this did not cure the problem.



Other than the erratic idle, the car drives really well and mpg is consistently good.

I think it's safe to say it is some kind of fueling problem but it doesn't seem to be the injectors.

I am no mechanic - I am just trying to narrow down what else to get changed/checked/swapped.

Thanks!

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Originally Posted by the surfer

Can this be done with an OBD reader? If so I can borrow one to use at home.

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Only if it will show measuring block data.

A reader that can display Live Data the VCDS Measuring Block equivalent when the engine is running. Usually such devices have the functionality to read live outputs, voltages, temperatures etc., etc. from the sensors / modules connected to the ECU. Readers that can identify the modules first and foremost otherwise they are not likely to work that well on VAG cars. ODB output is usually limited and a more detailed query level required.

I had the exact same problem with my 58 170PD. Turned out to be the Torsion Value was miles out after previous owner had a Timing Belt change. Took 4 different garages to actually get it right. Once it was within range car idled like a dream.

Unfortunately this is a Common Rail TDI whereas yours would have been a PD TDI and they don’t respond the way a PD does to the cam timing being slightly out.