Engine stalls 2000 ATJ

[Gaza 83]

HI i have 2000 passat tdi ATJ engine. The problem i have is that it idles very erraticly and sometimes stalls as a result, when the revs reach 2000 it runs up fine and is very smooth. Anything under 2000 rpm and it seems to stuggle to settle down. I have fitted new fuel filter, air filter and checked for split pipes. I have disconnected the MAF and it makes no difference to the running, VAG Com shows no faults apart from the fact i have disconnected the MAF but that clears when i reconnect. Don't know weather to go for a new MAF of look at the Tandem pump. Does anyone know how to test either or give me any pointers. Am not sure about Tandem pump as car runs smooth and well when over 2000 rpm. If this was a problem i think it would be running rough all the time. Thanks for any help. Gaza
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[kenney]

Check the status of the PD units in measured block values channel 13

[Gaza 83]

Check the status of the PD units in measured block values channel 13
Hi Measured block 13 gives values of 1 = -1.5 2 = 0.2 3 = 1.32 4 = -.05

[Gaza 83]

Found PD value status on measuring block no 18 all values are at 0 after 1 min of idling. Thanks

[kenney]

They seem to be ok,can you print a protocol for measured block values in channel 000.(Observe) the measured values are only valid when the EGR is switched on,when the engine is idling the EGR is switched off after running for a predetermined period,therefore give a burst on the throttle or restart the engine before measuring

[Crasher]

I can read your mind Kenney, it does sound like the EGR valve is stuck slightly open.

[Gaza 83]

Sorry guys got to to work now will try in the morning, If it is the EGR valve staying slightly open, can i replace the vavle or can it be cleaned. Thanks Gaza

[Crasher]

It may be gummed up, faulty or nothing wrong with it and it be the control solenoid (try disconnecting the vacuum line), that is if we are right and it is EGR related.

[Gaza 83]

i am unable to read anything in measured blocks 000, got vag com off of ebay so not sure it is up to reading that block. i have disconnected the vacum pipe off of the top of the EGR and it makes no difference!!

[Gaza 83]

am unable to read anything in measured blocks 000, got vag com off of ebay so not sure it is up to reading that block. i have disconnected the vacum pipe off of the top of the EGR and it makes no difference!!

[Gaza 83]

Finally found out that cam belt tensioner was faulty, when idling there was no tension on cam belt and when revs got higher the tension came back on which explains why the car ran ok with higher revs.
Very lucky boy that cam belt never slipped or broke. Full cam belt and stuff changed = no more probs.
Thanks for all help.