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Discussion Starter · #1 ·
just recently ive noticed my engine is making what i can only describe as a hissing sound and overall sounds a bit rough , any ideas what this could be , it hasnt effected performance i dont think
 

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Hissing usually indicates an air leak. Best way to tell is either stick it on a exhaust gas anyliser or get some brake clean and spray places in your breather system and gaskets etc. The spray acts as a seal for a moment and if you hit a leaky spot the engine will pick up.
 

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i had a kind of hissing noise but after i topped up the oil it went away and the performance seemed to change for the better...so much for the dealer checking the oil[:mad:]
 

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Hello Bob<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p>

Now I?m new to this forum and by no means a mechanic but I might be able to help on this one if you have not found the source of the noise yet.<o:p></o:p>

I have a v6 that had stated to do something very similar, but it turned out to be sucking in air not blowing it out.<o:p></o:p>

<o:p></o:p>

Now I?m not very technically minded when it comes to cars so you might have to bare with me as what I?m trying to describe.<o:p></o:p>

I think if I show you a picture it might be a bit easier! but what I found is there is a flexible bit in the pipe as it bends round the back of the engine and this had perished, it is an easy thing to check just take off the engine cover and follow the pipe round . With the engine running just try to compress the flexible bit together and see if the hissing stops.<o:p></o:p>

<o:p></o:p>

I have tried to mark on the photo where the pipe is that I?m referring to is, sorry for being a vague but like I said I?m not very technically minded.<o:p></o:p>

<o:p></o:p>

Hope this is of some help<o:p></o:p>

Al
 

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Discussion Starter · #8 ·
hi mate how you doin, thanks for your help mate . the car was actually in the garage on wednesday there getting new fans fitted and i mentioned the noise to him , he phoned me up later that day and it turns out one of the hoses from the air pump was broke so its been fixed now and everythings back to normal. well almost my engine light wont go away im thinking maybe the maf or something, but hey it wouldn't be a VW if something wasn't broken
 

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I had this start on mine about a year ago, the light would come on for a few days then go off, at the time I also thought I could be the MAF and it would be allot worse if the car had been standing over night and it had rained or was damp. It would then start to judder for a few minutes until the engine got up to temp. I did not do anything about it to start with as the light would all ways go out<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p>

After taking in to the stealers and them saying that there was a misfire on No1 cylinder but cloud not find a fault (there?s a surprise!) a few weeks a go it got really bad so had to do something and after reading on these forums a doing a bit of searching on the net in U.S. forums traced it back to the ignition coil pack that has a crack on it and was causing the spark to arc on No1 and now No4 cylinder. From what I have read on forums it seams to be quite a common problem with 4motions, changed the ignition coil pack and the HT leads all lights are now out and my MPG has gone up, every little helps.<o:p></o:p>

If it does turn out to be this, the pack and the leads cost me about ?196 all in from www.vwspares.co.uk <o:p></o:p>

Oh also this might be worth a quick check, there is a sensor on the back of the hose that connects to the air box ( I think that?s what it's called) if this is dirty or not connected properly it can cause the ESP light to come on and the engine check light. I didn't clip it back in place properly after changing the coil pack.<o:p></o:p>

<o:p> </o:p>

Hope this is of some help

Al
 

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Oh also this might be worth a quick check, there is a sensor on the back of the hose that connects to the air box ( I think that?s what it's called) if this is dirty or not connected properly it can cause the ESP light to come on and the engine check light. I didn't clip it back in place properly after changing the coil pack.
This sensor you are referring to here sounds like the MAF and has nothing to do with the ESP light. The MAF measures the air flow into the engine. The ESP is the electronic stability programme. The engine light can come on if the MAF is faulty.
 

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Discussion Starter · #14 ·
where is the MAF and what does it look like so i can unplug it and see if theres a difference in the car
 

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If you look at your engine from the front of the car you will see the air box to the right just above the battery. The MAF sits in the tube which comes out of your airbox, you will see the wire. It is secured by two security torx type screws.

I am about to take mine out and give it a good clean, see if it improves performance.
 

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There are around 4 pipes that perish all around the manifold... I did
Nosajs at awesome there is one behind the coilpack and one in front.

Anothere cause of the epc light is a faulty brake pedal switch... check the brake lights are working all the time.

also if the MAF is more than 50k old replace it often they will
just read low this is untestable withoput vag com and wont throw an
error code and also the dealers will not be able to find it

also clean the hall sender its a sensor plugged into the head just in front of the coilpack (I will try to get pictures)

prevent the coil pack failing by fowlloing this guide

http://chris.quietlife.net/passat/coilpack.html

however this type of all in one coipack was fitted to early 4motions and vr6's
 

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I had a similar problem recently. Turned out to be air getting
sucked into a split hose that goes round the back left had side of the
engine as you look into the engine bay. I replaced the hose with
some high pressure stuff I had lying round and all seems to be working
fine now!
 
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