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Discussion Starter #1
Hi All
Loving the forum. Who needs a haynes manual when we have a resource like this.
For those who haven't heard my limp mode woes I'll start at the beginning
Van is a 2007 T5 4motion 2.5 BNZ Engine 140PS

Problem started about 6 months ago. Intermittently going into limp mode, about every 100 miles. The problem usually happens early in a journey, and usually at the top of a hill. It can be reset on the ignition cycle and then the van goes back to normal. I do 100 miles a day so see this problem nearly every day and I'm falling out of love with my van a bit now!

I have been to my volkswagen trained independent mechanic a few times with it now. He said VAGcom logged an overboost code each time and suggested it was either turbo or n75 valve. He changed N75 valve, no fix. He replaced the turbo with a garrett one, no fix.

I have just taken it back in and got the code off VAGcom, it's P0299 Control range not reached. I said that is underboost, surely. He claims it was a different code last time.

I have suggested a pressure test of the charged air system for leaks would be the next step, do you have any other suggestions?

If my guy doesn't fix it this time I'm gonna go elsewhere.

Any suggestions
1) For things we can try while it's still on the ramp.
2) For garages/mechanics near Radstock, Bath who may be able to help me.
Cheers
 

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Discussion Starter #5
No pal if you remove header tank 2 screws you will see it under there on the pipe.Same prob I had was told turbo and al sorts found and fixed myself £2.75 in total T: good luck
Under the coolant reservoir tank? I'll give it a look tomorrow. Cheers
 

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Discussion Starter #7
Yeah m8 on turbo pipe T: VW fitted them with short harness you will notice how it pulls down T:
That would figure. Just went round to my mechanics workshop to check but he's locked it in for the night. I'll have a look in the morning.
Thanks so much for the fresh idea.
 

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Discussion Starter #9
Checked the sensor below the expansion tank. Loom nice and slack, wires intact. Have swapped the sensor out for another one while I was there. Perhaps that will do the trick? If not I'm gonna get a pressure tester for the charged air system and look for leaks.
 

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Discussion Starter #11
Yep that's what i'm gonna rule out next if still no fix. Cheers for the link, that's a useful resource.
 

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Discussion Starter #12
Checked the sensor below the expansion tank. Loom nice and slack, wires intact. Have swapped the sensor out for another one while I was there. Perhaps that will do the trick? If not I'm gonna get a pressure tester for the charged air system and look for leaks.
Limp mode again today so new boost sensor did not fix. Balls!
 

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Discussion Starter #14
MAF is clean and has power but have not tried swapping out the sensor yet. Actuator can be moved by hand (how much should it move?) and by applying suction to the pipe from the n75.
 

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Discussion Starter #15
Tried to get a look at the exhaust manifold today. The gasket appears quite distorted, is this normal? Where's the best position to get a good look at the manifold? Do I need to go in from Below and get the turbo out of the way?
I presume a leak here could quite easily be responsible for my underboost code?
 

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Discussion Starter #16
Ross Techs website is quiet handy:-

http://wiki.ross-tech.com/wiki/index.php/16683/P0299/000665

I'd check all boost hoses, Maybe for a cracked exhaust manifold :*

:ILU:
Just had a chance to do a thorough check of my engine bay and...... 2 x 1'' cracks in the top of the exhaust manifold on the cylinder closest to the air box. Does anyone have any experience of this fault causing limp mode and underboost codes?
I'm thinking of going for the PPT replacement manifold and blocking off the EGR Valve at the same time.
 

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I have the same problem and does alot of other ppl done every thing but change turbo. My van has only done 28000mls so thinking I don't need a new turbo well hoping anyway. I have learnt to drive with it I.e keeping the revs up not changing up a gear dropping revs when going up hill. And that works as mine used to do it near top of hills. Let me know if you solve the problem as my mechanic and I are pulling our hair out after testing cleaning and changing every but the turbo innotec cleaned turbo also
 

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Discussion Starter #19
I have the same problem and does alot of other ppl done every thing but change turbo. My van has only done 28000mls so thinking I don't need a new turbo well hoping anyway. I have learnt to drive with it I.e keeping the revs up not changing up a gear dropping revs when going up hill. And that works as mine used to do it near top of hills. Let me know if you solve the problem as my mechanic and I are pulling our hair out after testing cleaning and changing every but the turbo innotec cleaned turbo also
Hi ironlung. What model/engine do you have? It seems there 2.5l BNZ engines are particularly prone to split manifold as it is made of formed stainless steel rather than the normal cast mild steel. You'd have to be pretty unlucky to blow a turbo at 28000 miles although the amount of crud that EGRvalve seems to collect I suppose it's not impossible.

I was able to see my split manifold by just shining a torch down behind the engine onto the bit where it exits the cylinder closest to the air box. 2 hairline splits right on the top. Apparently it's always on this cylinder. VW should really improve the part. I'm certainly not going for another OEM one.
 
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