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128 Posts
Discussion Starter #1
Hello.

I wanted to ask this question because for the past few months I have been trying to get to the bottom of a fault with my 2005 2.5 AXD engine.

At first I was getting the elusive overboost fault on the engine and it was tripping into limp mode, this normally occurred above 3000 rpm. The local garage suspected it was sticky turbo vanes so the turbo was replaced. This didn't cure the problem though and so over the proceeding months I went through a regime of replacing suspected bits and bobs on the engine. This included the following, N75 valve and all associated vacuum hoses, boost pressure sensor, and finally I removed the EGR valve as it looked like it was leaking through the spindles.

Over the Easter weekend I had time to run a check using a VCDS computer and ran the van up a hill in 3rd gear with my foot firmly pressed down on the accelerator pedal. It looks like I don't have the overboost fault anymore so result! The graph below shows one of the tests (it was quite scary taking the van to nearly 4000 rpm!)...



I wanted to ask if there is such a thing as turbo lag anymore as although the overboosting seems to be sorted now the van still seems a little sluggish upto just below 2000 rpm, its roughly the point on the graph where the specified and actual boost pressures cross over. I know there will always be some lag as its in the nature of a turbo but is what I am experiencing normal?

Has anyone got any thoughts / opinions on this?

Thanks

Julia.
 

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Premium Member
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128 Posts
Discussion Starter #2
Hi.

Well this is all extremely frustrating. The problem still exists and to be honest the whole T5 thing is waning quite a bit now. Since I have had the van it has constantly emptied my bank account with seemingly fault after fault. New camshaft, turbo, alternator, starter motor, exhaust manifold (3 times) etc, and thats not including countless bits and bobs. I so wish I could get on top of the faults the van seems to be throwing at me.
This flat spot on acceleration doesn't seem to be consistent, it appears to be worse when the van is cold in the mornings. Once warmed up the lag is less obvious and if I give the engine some serious revs it seems to clear whatever problem it is having.
Its a sort of a plea really, I have thrown so much money at this and I don't know what else to do now. I really want to keep the van but all these issues are really taxing my resolve.

Apologies for the whinge.

Julia.
 

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1,883 Posts
No expert by any means, but I would suggest finding someone near you who is a Pendle agent, (Pendle Performance are in Barnoldswick, just north of Manchester & a well known font of knowledge on T5's) that could do a "live data" run on your vehicle. Obviously as well as this they could read what fault codes, if any, are logged in the ECU & go from there.

It is important to mention that not all actual faults show up as logged faults & sometimes you can have, for example, say a faulty engine temperature sensor that, although it IS faulty it doesn't show up as being faulty. The skill is knowing this & finding the fault.
Many people just assume that these days if the computer says your car has no faults then nothing is actually faulty that the computer is "looking at/talking to".

Don't loose hope !
 
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