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Discussion Starter · #1 ·
My van is a 2.5tdi on a 53 plate. It has suddenly started dropping power attwo thousand to three thousand revs. It us getting worse and I now can't get above forty in fifth gear. Engine also sounds rough when I put the clutch in and rev it. It still starts first time and sounds fine on tickover. Seems slightly better in the morni g when van is cold but it is still there.

I have heard people suggest maf sensor and I dud disconnect it and drive van. It wasn't any better or worse with maf disconnected.

Please help if you think it sounds familiar. It is like a major stutter that totally drops the power, almost as if I have braked suddenly.

Cheers
 

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Somebody stop me!
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MAF would have been my first suggestion but since to have unplugged it its obviously isnt the problem. You need to get it plugged in with someone who has vag com mate, its the only way to really find out on the 2.5tdi
 

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im wondering if the cam belt has slipped a cog on the fuel pump?

have you had any work on the engine recently?
 

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Discussion Starter · #4 ·
Thanks for the replies. I haven't had any work done on the engine. Is there any chance it sounds like MAF sensor still? I read that , if you unplug it, there should be a noticeable decline in performance if the MAF is working correctly. Is that right? When i unplugged it, I took it for a drive and it certainly wasn't any worse. If anything, it may have been marginally better.

i guess I will have to put it in somewhere eventually but I was kind of hoping someone might be able to tell me they had experienced exactly the same symptoms and it would all be nice and easy!

I have ordered vagcom as well so that might help throw up some suggestions. In the meantime, I have stopped driving the van, just in case the engine is about to blow up or something.
 

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Hi Pamster,

If performance improves with the MAF unplugged it could still be the MAF.

To prove it you would need to hook it up to vag com and read the measured values as sometimes the MAF doesnt throw a code.

A simple way to tell would be to borrow someones MAF.

Where in the UK are you ?
 

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Discussion Starter · #6 ·
I was thinking about borrowing a MAF but I don't know anyone with a 2.5tdi van. However, my sister has just yesterday purchased a 1.9tdi and I am going to head round to hers tonight to see if the 1.9 has one. I have read on here that some say the 1.9 doesn't have a MAF but i have also read others referring to it as having one. Any ideas?

I am in Alloa in Central Scotland but i don't have any T4 friends:( I am thinking this forum could be a good way to get some though! I feel totally lost without my brother, who is my usual font of all knowledge in any technical matter, but he is training to be a firefighter and is away for twelve flippin weeks.

This is what happens when girls get into boys' toys: I managed all the carpeting and cosmetic stuff but I am a bit stuck with the old engine!!

Cheers for repliesT:
 

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Some more detailed info here....

http://www.vwt4forum.co.uk/showthread.php?t=52003

PS take the maf plug out check inside for the little brass connections make sure they are all pushed in far enough..... i had this problem after messing about with the air box worth a look:ILU:

B*gger promised me self i wouldnt post again:D
 

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I was thinking about borrowing a MAF but I don't know anyone with a 2.5tdi van. However, my sister has just yesterday purchased a 1.9tdi and I am going to head round to hers tonight to see if the 1.9 has one. I have read on here that some say the 1.9 doesn't have a MAF but i have also read others referring to it as having one. Any ideas?

I am in Alloa in Central Scotland but i don't have any T4 friends:( I am thinking this forum could be a good way to get some though! I feel totally lost without my brother, who is my usual font of all knowledge in any technical matter, but he is training to be a firefighter and is away for twelve flippin weeks.

This is what happens when girls get into boys' toys: I managed all the carpeting and cosmetic stuff but I am a bit stuck with the old engine!!

Cheers for repliesT:

appologies - my geography is aweful.

1.9 T4's dont have a MAF I'm afraid. 1.9 TDI's are another matter but they are not T4 vans.

if you genuinly feel that the performance is better with the maf unplugged its highly likely you have your problem. If there is a friendly independant garage around that has vag com you could always ask them to check it as another option.

Regards.

Ron.
 

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Hi,

you say the engine sounds rough - does it sound like the exhaust is blowing badly when you rev the engine (but ok at idle as not being loaded).

Mine has just developed loss of power and I actually thought the exhaust had a huge hole in it.

VAG-COM reports 17964 - Charge Pressure Control - Negative Deviation. (I have no CEL/MIL on the dash). This code suggests a problem with the N75 valve, associated pipework or EGR. An easy check is to make sure all cables are fitted correctly and securely.

Incidentally, my issue has only occurred sine I blanked off the EGR pipe and fitted the power pipe a few weeks ago, so its definitely something related. Ho Hum.
 

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Some T4's have 1.9TDI's fitted but are very very special and hard to find.

Send T4virgin a PM he's up your neck of the woods and is a good honest member on the forum,im sure he will be happy to help.

p.s. he's single too T:
 

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Discussion Starter · #11 ·
Right. I have an update on all of this. I have been reading lots and lots of forum posts and was pretty sure it was MAF sensor but I ordered a vag com lead and software so I could check.

I did this test in vag com where i had to go into Engine section and floor the throttle in second gear to get a MAF reading. somebody somewhere suggested that a reading of less than 700g with this test suggested MAF failure. Guess what? Mine was way less than 700 and I did the test a good few times to maike sure.

So, the van was worse than ever and virtually undriveable and I needed to get to Euro car parts for replacement MAF as they were only place I could get one in stock at decent price.

I took the old one out again and it was a whole lot better to drive, so i risked the trip to Glasgow with no MAF at all, swapped the MAF for a new one (they needed old one for reconditioning to get cheapest price) and drove home with a much improved van!! Wahey!!A:

I wouldn't say that it is 100 per cent yet though as I am still getting hesitancy at higher revs but it is so much better it is unbelievable.

Will it take a while for new MAF to 'settle in' and ECU to adjust or something? I read somewhere that disconnecting the battery for ten minutes does the trick.

Any ideas? It is much much better but just not totally hesitancy free. Doesn't sound rough at all anymore, just the quiet whistling of the turbo.

Phew. Does it sound fixed?

P.S T4 Virgin not my type, if you know what I mean...no disrespect to him but i am happily loved up with female partner these days!! ;)
 

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Discussion Starter · #13 ·
It's just like a little dead spot then it picks up again. It's basically a much less severe case of what it was doing before.

It's smooth up to 2500-3000 revs and then it goes flat, like someone taking foot off throttle or tapping on breaks, except my foot is firmly to the floor and it should be accelerating all the way.

I read someone saying that it takes the ECU a wee while to readjust to the new MAF sensor and that disconnecting the battery for 10 mins should sort it. I wondered if it just needed a good run as well.

Anyways, I am pretty confident it was the MAF because it was instantly much much better when the new one went in. Does that sound like a sensible conclusion?

It's just not back to 100 per cent yet.
 

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07415125940
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I've not heared that before about the maf taking time to settle but I never say never these days.

Are there any codes on vag com ?


Sounds like you found the main issue as you say.

Regards.

Ron.
 

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Sounds like a leak on one of the turbo pipes. But then again I'm no spanner man:(
 

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Discussion Starter · #16 ·
:):):):):):):):):):):):):):):)grrrrreat news on power loss problem. It was definitely the MAF sensor.

It was still stuttering and dropping out of power really badly, even after the new MAF so I disconnected battery neg terminal for an hour or so while I was at work. Reconnected it after work and the drive home was awesome! Best the van has been for a while.

So, I guess it's best to reset the ECU after fitting a MAF. Makes sense, I suppose since the ECU probably had to adjust itself for MAF being faulty and then has to go back to normal when the new one goes in.

Thank goodness it was a nice and easy thing to fix and nothing more expensive. I'm resolving to look after my turbo from now on though as I really feared that was the problem!

Thanks for all advice here.

I now have vagcom for future diagnostics as well so I'm glad I fixed it myself. I'm well chuffed.
 
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