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Discussion Starter #1
Right guys, hopefully someone migh me able to help me with this one.

I just bough a late 2003 T4 factory kombi 2.5 88Bhp. Its a one owner bus but it has sat up in a shed for 3-4 years.
It drives great. Engine smooth with no misses. The only thing is that its down on power. It feels like its at 70% of what it should be. Its really noticeable on a long hill.

Heres what we've checked so far:

  • Full service with all new filters
  • Timing belt, pullys & pump
  • Replaced Air flow meter
  • Replaced MAP sensor
  • Swapped out N75 Valve
  • Checked & rechecked all vacuum hoses
  • Removed, cleaned and blocked off EGR
  • Actuator moving freely
  • No errors on VCDS

But its still down on power. The only thing left that I can check is either a blocked Cat or bite the bullet and remove the turbo and check that the vanes are not stuck.

Can anyone shed some light on the situation? Its driving me round the bend :confused:
 
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Won't have vanes stuck Brian it's not a VNT, can you hear feel it boosting? Have you checked the actuator is moving and are you sure the sensors are all ok? Not a first for replacements to be faulty, do the simple checks on them using VCDS T:

Also may sound silly but are you sure you're just not used to driving something with a but more umph and expecting a bit too much from it :*
 

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My AJT was fairly slow when I got it. Limp mode etc. Eventually got it to the point that your at above then.

Clean and blank the EGR.

I decated mine with a 1997-1998 2.4 d silencer pipe. Straight swap but hard work to get the three bolts out on the flange.

Fitted an ACV intercooler.

STP fuel injector pre NCT diesel pack plus regular doses of dipetane every couple of fills.

It pulls nicely up hills now. The decat probably made the biggest difference to the hills but all of the above gave a small improvement. Flys up hills now.
 

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Discussion Starter #4
Won't have vanes stuck Brian it's not a VNT, can you hear feel it boosting? Have you checked the actuator is moving and are you sure the sensors are all ok? Not a first for replacements to be faulty, do the simple checks on them using VCDS T:

Also may sound silly but are you sure you're just not used to driving something with a but more umph and expecting a bit too much from it :*
Alright Dan,

No I have an 88 here as a work van, so I'm use tho them slow T4's Rasp:
The actuator is moving freely when you push it. I've swapped out the Air flow, replaced the map and swapped out the boost solenoid (n75) and still the same.
It seems there is little or no boost. Can't hear the turbo spooling up at all.
There is no air leaks

???
 

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Has the timing been set up properly using VCDS?
If the EGR and cat are not blocked, you need to do some live data logging using VCDS.
Log measuring blocks of requested boost, actual boost and N75 duty cycle, and requested MAF and actual MAF, and injected quantity. (3rd gear, full throttle, 1000 RPM - red line)
Check all the temperatures in measuring blocks.

These slightly down on power issues don't normally throw any fault codes.
 

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Discussion Starter #6
Is there anywhere that I can get the figures?
Or better still a walk through of which blocks to test.
I have a fully registered up to date VCDS but don't know all of the functions.
 

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I've had these exact symptoms on our AJT after much faffing discovered the fuel pump had been mistimed - 2 teeth out after cambelt change :eek:; the turbo was quiet as a mouse :cool:
 

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Discussion Starter #9
Cheers guys, will stick it back on VCDS today and see if I can find a timing problem. If not I'm burning it I:
 

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Discussion Starter #11
Right I have an update.
Pump timing was woefully retarded so have that sorted now. Running a lot better but still not 100%
Next stop is a de-cat pipe.

Will update when fitted T:
 

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Discussion Starter #13
If that doesn't improve things, can you do a compression test on it?
It's running 10 times better since the pump timing was done. I think its down to what Dan said earlier - that I'm not too used to the 88Bhp. I've always had the 102 and this one is a LWB factory kombi.
So maybe I'm expecting too much from the ol' thing :*
 
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