idling high ( 1000rpm)

[jazzygwd]

evening people.just joined the furom and hoping somebody out there has an answer to this as it seems a common fault. i have a 1.9tdi bxe engine and on 170k..this car has been fantastic till recently when sitting in traffic the engine just started to raise its revs up to 1000rpm.

so took it to garage ( friends ) and plugged in > absolutely no codes bar glow plugs which always seem to be on whenever i do a service reset and neer been a problem.
things noticed > fans seem to come in although engine may be t whatever temp...even at start up when cold or when hot
changed coolant temp sender
changed maf sensor and these two things have made a very big improvement to my acceleration but still this idle issue
changed egr
measured alternator and is putting in 14.1 constantly
tried having air con on and off and doesnt matter as 14.1 will always go back at the battery

history wise for the vehicle i havent had air con topped up for 5 years so could it be that?
always change oil every 8k and filter plus service it regularly....also had air filter/pollen/and fuel filter done not long ago.

could it be:
air con pressure sensor
fan switch ( which i seem to think is below main air intake at front of car )
or the vacuum box ( not sure correct name ) at the rear of the battery on chassis. this seems to be working as can hear it
lamda if it has one

im completely stumped with it and just frustrated with it really.
i travel on motorway to go work so it does get a run everyday and not like im pottering to the shops

any help will be gratefully received guys

matt

[RichardSEL]

You don't say what you "plugged in" with. Sounds like DPF regenerating and, at 170k, it can't complete coz DPF has reached the end of its life. A VCDS Autoscan would tell much more.

Dunno where you are but in England there are many VCDS users that'll do a scan for you for beer tokens

[jazzygwd]

Hi richard thanks for reply...ive plugged in again to a snapon d10 reader so shoukd be good enough to read. Today i went into the dpf regeneration part to do a regen and it reckobs it doesnt need it as at 50 and not 90 could have still done it but advised to leave this time around....so im now thinking getting aircon topped up and seeing as well as getting fan switch....any ideas bar that

[DMitch16]

Static regenerations should be done as a very last resort as they can go badly wrong and are not good for the engine. Why is the car not regenerating normally i.e. at 45% soot load?

[jazzygwd]

Computer said it was at 50....im not a technician and thats why im asking for advice....i can only tell you guys what im being told by reader and it said it wasnt necessary...i dont know too much about dpf so please bare with me as im just trying to find out what route to go down without throwing money towards the car as i do love my passat and it has been very loyal. Could i be thinking ecu then from what you are saying

[RichardSEL]

I've always thrown money at what I love
So get yourself a VCDS Autoscan and post here.

PM me your email address for a DPF help .doc by return attach

Do not rely on any other reader for VAG cars. A Snap-On D10 is not good enough

A user location map's here. I'm in SE London but won't be doing VCDS for much longer as sold with car due delivery soon
Here's the URL:
https://www.google.com/maps/d/viewer?mid=zwQHurSsCMz8.kMTwqF0PoXwc&msa=0&ll=56.2 31139%2C-2.779541&spn=3.493691%2C10.821533&iwloc=0004c505cf cb6158e0447

[Shab2015]

I had a very similar problem with my Passat tdi. It would idle higher all of a sudden at lights and glow plug light when turned on in ignition would stay on for ages.
I had the temperature sensor replaced and all solved. Maybe get some readings on what the sensor is showing


Sent from my iPhone using Tapatalk

[jazzygwd]

Hi guys update on this problem...ive now changed both temp senders. And the maf which has made the car run and accelerate lovely...plugged back in and watch everything data wise and car typically never done it so.......replugged in when it had and noticed an error code of 01598 drive voltage intermittent... alternator putting in 14.1v when idling and 13.9v when i switch aircon on....
Did notice the fan cuts it as it does it for about one or two minutes as well...3 things im thinking but dont want to keep chucking money at it. Could it be aircon need regassing as seems to take ages to get cold ....alternator irregular as read a few things and also battery cell down although battery starting car lovely and green visual saying its ok on top of battery......thanks in advance

[DMitch16]

Could also be a short in a wiring loom. Check all wiring looms around the engine and make sure none of them are or have come into contact with hot metals such as the exhaust parts or heatshields. A loom contacting a heat source like these will melt the outer casing, melt the wire insulation and cause the metal wire to contact another metal source be it another wire or a metal surface.