Rail pressure too low after filter change '09 3.0

stefan2m

Member
Joined
Nov 11, 2014
Location
Netherlands
TDI
CDYA 3.0 tdi
Hey guys, I have a problem I'd love some help with.
I bought a 2009 A6 Allroad 3.0tdi (CDYA) about a month ago and changed the fuel filter as soon as it arrived, but I messed up.

Old filter looked fairly new when I took it out, but I always do this when I buy a new to me car, so changed it regardless.
Previous cars took a 3rd party cable and a registered version of VCDS lite, but since that doesn't work on the C6, I couldn't prime the fuel system that way and just cycled the ignition on and off a couple of times before trying to start.
Took a little longer than normal to start but didn't miss a beat; preheater light was flashing though, let it idle for a while and then took it for a test drive, had power loss until I shut off the car and started again.
Now I have a obd eleven to read codes, and the only fault code stored is P0087 for rail pressure too low.
When I have power loss there is also a code stored in the tcu for loss of functionality due to ecu, so that's limp home related, I'm not worried about that.
The flashing preheater light does come up once in a while though, maybe half the times or less when I use the car; 9 out of 10 times without going into limp mode, but does idle a little rough at a slightly lower than normal rpm.
Engine off and starting again = light gone every time.
After clearing codes it doesn't come back until I start the car and the lights starts flashing.

I have the filter style with four slip on hoses and no connections with o-rings, there are no leaks visible, absolutely no smell.
Transparant fuel line on top of the engine has no air in it
It's a Mahle KS-659 filter from a known good reseller (good parts for good prices, sucky service).
Before changing the filter there were no problems.

I am guessing I have air somewhere in the high pressure system, but I don't know if that's possible with a common rail? Could I have damaged the hpp this way?
Would love some suggestions and/or insight... I don't have VCDS, but I can read live data with the obd11 app.
 

joep1234

Veteran Member
Joined
Jan 2, 2014
Location
NC
TDI
former '04 Beetle TDI, now 2x '15 Audi Q5 TDI's, 2007 Dodge Ram 4x4 6.7
Is there any chance that the filter is in backward? How many miles are on the car? How many miles did you drive since the filter change?
Sorry for all of the questions but think this may help.
 

stefan2m

Member
Joined
Nov 11, 2014
Location
Netherlands
TDI
CDYA 3.0 tdi
I’ll check again when I get home from work, but I think it’s in correctly. The car is at little over 143,000 miles now. I drive a minimum of 250 miles a week, so let’s say 500-750 miles.
I don’t mind questions Joep (Dutch name, have roots here?)
 

turbobrick240

Top Post Dawg
Joined
Nov 18, 2014
Location
maine
TDI
2011 vw golf tdi(gone to greener pastures), 2001 ford f250 powerstroke
The air should bleed itself out after it runs for a brief time. Next time just fill the canister with fuel manually prior to buttoning it back up. It's more effective than VCDS priming for a simple filter change.
 

stefan2m

Member
Joined
Nov 11, 2014
Location
Netherlands
TDI
CDYA 3.0 tdi
I had an appointment for remapping today, decided to go there despite the problem as these guys are specialised in VAG, and they’re busy so there is about a month waiting time even in these times.
The owner advised me to change the fuel filter for a another one (so I ordered it), but noticed the problems were only there at idle; that would suggest a failed/failing quantity control valve. So... will see what a new filter brings (ordered a Bosch this time).
And it made 300.1hp/606.7Nm (447lb-ft if I’m correct)
 

stefan2m

Member
Joined
Nov 11, 2014
Location
Netherlands
TDI
CDYA 3.0 tdi
Little update; I went in to get the part number, and decided to spray a bit of contact cleaner in the plugs and let it sit for a few minutes. Also tapped on the housing (lightly) with the stem of a hammer.
That was sunday; saturday symptoms were getting worse and more frequent up until the point it would even stall on idle a few times.
Now it’s wednesday, have not had symptoms once (new fuel filter in the mail) !
Fingers crossed... but might have dodged a bullet here.
 
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