1.9 tdi really sluggish

[zmotor]

Hi, this car is really starting to test my patience......a bit of background

Audi A4 1.9 PD130 AWX currently at 156k miles

Oil and oil filter service every 5k, ran on shell V-power diesel for the last 20k

Ran great till a couple of weeks ago, after a nice 150mile trip i parked up let it cool then switched off, when i went to work the next morning it was a totally different car....very lazy and sluggish below 2.5k and very hard to get up to speed without really working the car. If i plant my foot in pretty much any gear it took an age before boost, between 1-2.5k it`s as if the turbo is asleep

Only code i got was for a fuel temp sensor which presented when i changed the tandem pump seal + coolant pipe (yes it was plugged back in and no the ignition wasn’t on when it was unplugged..logs showed it stuck at 40.5 which changed when it was replaced)..strangely enough the code only appeared 3-4 weeks after the problem and pretty much straight after the tandem pump seal replacement. I also checked the fuel filter and there is no oil present to suggest possible injector seals, oil stays at the correct level suggesting no fuel/oil mixing via tandem pump. The car starts on the button every day, no smoke...just very sluggish below 2k in low gears going up hill if i plant my foot nothing happens till +2k...on the motor way its generally ok as its above 2k but does require more throttle to keep up to speed compared to before

I didn’t log the fuel temperature when the problem occurred, the recent cold bite may have killed it but even after replacement it has made very little difference...

Cars had the following done:

Fuel filter (changed yearly)

Timing belt (two years ago)

Coolant + CTS + thermostat + viscous coupling (changed two years ago)

Fuel temp sensor (recently)

N75 valve (changed a year ago)

Map sensor (changed a year ago)

Injector harness (recently), cam is fine...injectors have never been touched

MAF sensor (changed a year ago)

Actuator checked, holds vac

Turbo vanes are free and clean, turbo blades are nice too minimal play

CAT isn’t blocked, neither is the EGR or intake

Vac lines are all good so are all boost pipes, clamps + intercooler + in line check valve is good and the right way round..vac reservoir is solid..intercooler sound resonator is tight too.

Tandem pump seal replaced (pump is still weeping from the back plate, so a new pump is on its way)

Checked for broken wires/damaged harness....nothing

All bosch/pieburg/genuine parts used

As far as i can tell, everything is where it should be in regards to turbo/airflow..suggesting a fueling problem as the car is still sluggish... the tandem pump has been leaking for a while as the coolant line below it was very swollen and soft hence my motive to change the seal...as i said the back plate is still leaking so i will be replacing the pump...is this my problem? the leaking back plate drawing in air? i am unsure as its been leaking for a while but the car has always ran well...leading me believe this may not be the problem. I also thought the accelerator pedal but the car revs up fine at idle

I have attached a log file...any help/advice is greatly appreciated.

Dropbox - LbigOG-01-019-022-036-071-116-13F.csv

Asad

[zollaf]

the maf sensor you replaced, what did you use, was it a genuine one from a dealer ?

[zmotor]

its a bosch one from eurocarparts, its been on there for a year or so without problem (car ran great), i did swap it with a brand new replacement item from eurocarpart with no change so i put my old one back on and thought to look else where....

[Doctle Odd]

Have you had a diagnostic scan done?

[zmotor]

yes i own a vcds cable , nothings come up since the problem started only the fuel temp short to ground when i replaced the tandem pump seal, a log of which showed it was stuck on 40.5 continually...it was plugged in when i reassembled, i cleared the code and it returned so was definitely faulty just took its time to show up. I thought this was my problem, however since replacing it very little has changed

[arman123]

Don't the tandem pump also do the vaccume for the car? you might need to change the pump or look around the pump for any split pipes vaccume side

[zmotor]

yes they do, inner part is for vac outer is fuel, all lines check out ok ive also epoxied the main vac line port as it was loose....replacement pump is on its way

[nevo]

Have you got a vac gauge,"T" it in to the line to the turbo.

[zmotor]

Ill get it done and report back when i return home next weekend

what readings should i see?

[zmotor]

any more suggestions? will be checking the vac this weekend