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Discussion Starter #1
Hi everyone, I've had my V plate 2.5 tdi for seven years now, and boy do I love it! But........ I've had a problem happen to me a couple of times, and I don't know what it is, or how to overcome it, but it rights itself in a couple of days! It's all to do with rian and water. From startup the engine goes into an idle only mode at about 1100 rpm, I can actually drive it (to get home) but what a pain in the ass! Not only for me but other road users, Guess what? It happened today, at 07.20 when I needed to get to work, as todays work is 35 miles away, I'm staying at home, playing with my teapots. I'm going out to look under the bonnet now, perhaps with a hair drier! Anybody got any ideas? Oh while I'm on it, can anybody recommend a VW specialist who is honest and trustworthy in the Exeter/Devon area? At the moment, money's not what it once was! Thanks to all, Brendan.
 

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2.5tdi = electrically controlled engine = has an ECU = First port of call it to get the thing plugged into a diagnostic machine and see what faults it brings up.

You can do this yourself if you have a laptop, the leads are about £10 from ebay, and the software is £100. Much cheaper than a garage.

Typical limp mode probs on the tdi are faulty N75 valve (boost pressure control solenoid), Incorrectly plumbed vacuum hoses (to the N75 valve and the ecu) or a dodgy MAF sensor.

You need to do a search on all these subjects, there is hundreds and hundreds of threads on all of this.
 

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Discussion Starter #3
2.5tdi = electrically controlled engine = has an ECU = First port of call it to get the thing plugged into a diagnostic machine and see what faults it brings up.

You can do this yourself if you have a laptop, the leads are about £10 from ebay, and the software is £100. Much cheaper than a garage.

Typical limp mode probs on the tdi are faulty N75 valve (boost pressure control solenoid), Incorrectly plumbed vacuum hoses (to the N75 valve and the ecu) or a dodgy MAF sensor.

You need to do a search on all these subjects, there is hundreds and hundreds of threads on all of this.
Thanks for that, I did actually buy a vag com lead for my laptop, and guess what, the software won't work with windows 7 home premium! What software have I got? I feel like unlucky Alf from the fast show! I've read a few posts quoting bits and pieces about MAF sensor, but, what is it? where is it? and what does it do? Cheers.
 

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MAF = Mass Air Flow. It tells the ECU what volume of air is entering the engine. You can find it behind the windscreen washer bottle. Looks like this

Here is a link to a thread all about it

Another thing to check is if the inlet pipe to the turbo has a tight seal. If the seal has worn, it will be letting un-metered air into the engine which will mess up what the ECU is doing. This can be resolved with an 'o' ring.

Also read this thread on the N75 valve and Vacuum hoses.

As for vag com and windows 7, im pretty sure it is possible to make it work, but you have to fiddle about. Did you download the newest version of the software from the Rosstech website? Also try searching for vagcom. Im sure i have read a thread about getting it to work on win 7

Good luck mate, the 2.5tdi is not such a complicated engine once you get your head around the diagnostics processes. Its also pretty bulletroof.
 

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Discussion Starter #7
Good point! I had it removed for some work for an MOT, the garage asked me if I wanted it put back, but said it was bent, possibly naively I said no. There looks to be a possibility that decision might have come round to bite me in the ass. Perhaps I should look around for a replacement bellypan, once I have sorted my present woes. Good thought though, today I can lie on my drive in the wet, and see what might be blatantly hanging off, or not. Thanks for that! Brendan.
 

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Discussion Starter #9
Hello everyone, are we sitting comfortably? Then I'll begin..... Just a follow up, but there's a tale here. Gave my van to a company in Exeter called Electro Diesel. Somewhat stupidly, I thought they'd find the fault in about an hour! They were very busy though, four days later they rang to say it was all fixed, turned out to be a fault in the wiring loom in the engine bay. The loom had been rubbing against something and shorted out. The guys at Electro Diesel replaced cables and even gave me an A4 colour photo of the faulty cable. On top of this I was scared to death what the bill would be, but it came in at just under 200 quid, very good I thought. But the tale is....... DON'T PANIC ! years ago I would have spoken to people and changed this and changed that, and spent a fortune replacing things that didn't need replacing, find a firm you can trust, and let them do it, praise be to Electro Diesel!
 

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T:
Thanks for that, I did actually buy a vag com lead for my laptop, and guess what, the software won't work with windows 7 home premium! What software have I got? I feel like unlucky Alf from the fast show! I've read a few posts quoting bits and pieces about MAF sensor, but, what is it? where is it? and what does it do? Cheers.
Ity does mate I have it but had to get my IT mate to set up the diag lead T:
 

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Hello everyone, are we sitting comfortably? Then I'll begin..... Just a follow up, but there's a tale here. Gave my van to a company in Exeter called Electro Diesel. Somewhat stupidly, I thought they'd find the fault in about an hour! They were very busy though, four days later they rang to say it was all fixed, turned out to be a fault in the wiring loom in the engine bay. The loom had been rubbing against something and shorted out. The guys at Electro Diesel replaced cables and even gave me an A4 colour photo of the faulty cable. On top of this I was scared to death what the bill would be, but it came in at just under 200 quid, very good I thought. But the tale is....... DON'T PANIC ! years ago I would have spoken to people and changed this and changed that, and spent a fortune replacing things that didn't need replacing, find a firm you can trust, and let them do it, praise be to Electro Diesel!
I'm bumping this old thread to see if you could post up a pic of your faulty cable whereabouts, I'm suffering from similar and am also in Exeter

Cheers
 

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T:Most of the wiring faults are generally in the conduit just as it goes over the engine from the bulkhead. Strip the plastic conduit back and have a good look.
 

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Mine was the throttle potentiometer playing up fooling the ecu and went into limp mode
This has just happened to my R reg 2.5 tdi. Garage say it is the throttle potentiometer and that it may never happen again, so best leave it and see how we go.
That seems a little bit reckless, has anyone been in this situation and resolved it??
 
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