Loss of power - slipping clutch or boost leak?

[AL_B]

Drill,

I have just no idea mate. No idea at all now on what might be causing this.

At the weekend I went over things again. I checked, as best I could, all the vacuum hoses. The only one that caused a little concern was the fabric-braided vacuum hose going from the Fuel Pressure Regulator to the underside of the intake manifold. It isn't very tight at the FPR end, and it didn't take much the pull the hose off, even with its little clip still attached. So....could be loosing vacuum there perhaps.

Also at the weekend, I have re-fitted my old MAF. No point in "burning out" the new one, if it isn't solving the problem.

After that, I did basic settings on the MAF, TBA, did the lambda tests again, and did the throttle body and pedal sweeps. Need to check the pedal/TB sweeps, but everything seemed ok.

Today the car has had one slight instance of hesitation, but has regular surging on part-throttle.

I did try to service the Forge DV at the weekend, but couldn't get the b'stard thing undone. Looked a bit mucky on the side of the piston though. But its travel was smooth, and held in place ok with vacuum.

Also tried to fit the AmD intake pipe strengthening sleeve, just to rule out the pipe collapsing theory, but would it slide down the intake pipe - would it f###.

Not a good weekend really.

AL

 

[AL_B]

A brief update for folk who are still interested...is anybody still interested in this?!!! I know I'm bored of it too! /ubbthreads/images/graemlins/smile.gif

On Tuesday car had a massive hesitation on the way to work, 5th gear, approx 4000rpm. Must have lasted for a good second. That evening I decided to tinker around a bit more.

Firstly, I noticed that the hose clip that I had used to securely hold in place the Crankcase Breather hose, had cut through the hose. B#stard. I must have over tightened it when I replaced the loose OEM clip.

So I temporarily patched up the hose with insulation tape, and tightened up the jubilee clip - but not too tight this time. Hose moves slightly though, which I am not happy with.

I also noticed that the side hose going into the DV had slipped back slightly towards the charge air pipe. So I pushed this flush and tightened the clip. Despite doing this I noticed last night that again this hose had again slipped slightly. So a bit more tightening is needed, but I'm worried about damaging the hose.

I've also been having a read on Elsawin, and there is a technical article on engine coking "Cleaning of coked engine parts (17156)". Over time, injectors, combustion chamber surfaces and intake system can become coated in carbon deposits, causing running problems on cold starts and loss in engine power. The article continues to say that they (Audi) tested various products for cleaning the fuel and intake system. (I'll try to post a copy of this up soon)

Based on that article I decided to try some of the "Wynns Fuel Intake and Carb Cleaner" that used for cleaning the throttle body. NOTE: This is not one of the products that Audi tested, but I decided what the hell, give it a try.

So I performed one part of the steps recommended on the back of the Wynns spray can. That was, with engine idling, spray a few short bursts down the air intake. I just disconnected the turbo air intake after the MAF, sprayed 1 burst, waited a few seconds, sprayed another. Did this about 4 times. I then went for a drive to "burn" it out of the system a bit more.

Driving the car the next day to work, I noticed surging on part throttle had been reduced significantly, i.e hardly surging at all now. And since then I have not had any hesitation either. But it's early days yet. But on the whole the car seems to be running slightly better.

Personally, I think the patching up and tightening of the crankcase breather hose probably had the most significant impact, rather than the Wynns. So I'd recommend checking that hose is tight and not split.

Sorry, there's more ramblings...

I then read more about the Positive Crankcase Ventilation system and its valve. The Wynns can recommended squirting the carb cleaner into this valve and working the valve, to clean it out. I didn’t do this, as I don’t know how to “work the valve”.

The inside of the PCV valve can get coated with oil and deposits over time. As the engine "breathes" through the top of the crankcase, the air in the engine will contain a fine mist of oil. This gets released out via the PCV valve, back into the turbo air intake hose (on my BAM engined S3, others may connect to the air box). It’s all to do with emissions. The oil/air mist is not allowed to be vented out to atmosphere on some modern engines.

So, that oil mist gets cycled back round the system again, which is why a fine coating of oil can be found in the charge air pipes, intercooler pipes, throttle body and intake manifold etc. I guess this isn’t necessarily bad, Audi must know this will happen, but I guess sensors, pipes, solenoid valves (e.g. N75, N249, Wastegate etc.) will all get a fine coating of oil within them (?). As items like the N75 and N249 get their vacuum from the intake manifold. For example, the little hose going to the FPR on my car is a little loose. When I removed it, there was a fine coating of oil on the FPR hose nipple.

Like I say, I’m not sure if the oil coating is anything to worry about, but I think a bit of a clean up won’t do any harm.

Anyway, thought I would share the above with you.

Comments, corrections etc. are welcome.

AL

 

[Khufu]

Always interested Al, it must be a nightmare for you. I know what you mean about inside the throttle housing - I cleaned that on my old BMW. who ever had it before had been adjusting the throttle stop screw to keep the idling correct. When I cleaned it out around the butterfly the car idled at 2000rpm until I corrected it back down again so I guess things like that can matter - especially if the car compensates and it is miss-matched to the throttle position sensor etc.

I guess part of the question is - is it only the turbo models or is it just more obvious on those. I do get a very slight surge occasionally, usually when gently lifting off on the throttle but it is very slight. Its like the car is supplying a bit more fuel to compensate like it does when at rest and you move off without enough rev's it blips them ( i can feel the pedal sink slightly which is strange as my car is non-dbw)

You must be at the point of being able to write your own book on the matter!

 

[evotista]

Keep the reports coming AL, there's plenty of us still interested. I wonder if you could post up some pics of where the crankcase breather hose is and where the PCV valve is. I know you said you've checked all the vacuum hoses, but i remember Foolish told me sometimes finding splits is very hard in them...i wonder what the cost would be to replace these, i wouldn't have thought it would be that bad to a rolling replacement of them....probably cheaper than replacing the throttle etc?

I struggle to see what other DIY options you have , everything beyond what you've done is going to get expensive i would have thought...fuel system checks, clutch etc...short of the remap approach, how about approaching a genuine bosch me expert....i might be able to dig out a name or two when i get back this weekend...or how about Mike down at Jabba for whomo Ryanc has lots of positive comments.

Regards

 

[Ryanc]

mike at jabba knows his stuff from my many chats with him.Steve tells me minhea from mrc is also very knowlegable.
The bosch motronic is so complicated it could be so many things.

 

[AL_B]

Guys, thanks for the positive comments. I tell ya, it keeps me going.

Khufu, it is a nightmare mate. I don't know about being at the point of writing my own book, more like at the point of selling!! /ubbthreads/images/graemlins/smile.gif

Martin (evotista), I will try to post up some pics of the crankcase breather hose and PCV valve (aka Pressure Regulating Valve in the Elsawin). It could of course be different for your quattro A3. Unfortunately I didn't take any pics of the split in the hose - was too p#ssed off at myself for making it split by over tightening the jubilee clip.

I too remember foolish's post. Finding splits is a nightmare. Going off what I know now though, you could probably find them by looking for slight oil seepage or you can use Ignition Starter spray or Audi's own Leak Detector Spray. I haven't done this in anger though. Just visually inspected stuff. But some are very hard to get at on my engine.

I think replacing most/all hoses would cost a tidy sum, along with clips. There are just so many.

I would appreciate a name or two of some bosch experts. They might be able to suggest things or investigate.

Ryan, Martin,

I know what you are saying regarding Mike at Jabba, but I have now visited two tuners, Awesome and AmD, both were friendly, helpful and happy to investigate...but didn't find the problem. Leaving me a couple of hundred quid down. So I'm a bit reluctant to try somewhere else. Kind of bitten twice, don't want to get bit again sort of thing.

Anyway, car is still hesitating despite the clean up. But tightened the hoses again tonight. My insulation tape patch failed due to the oil from the crankcase making the tape un-sticky. So I've chopped the split part off, refitted the hose, and re-clamped.

Up to Scotland this weekend, so I'll see how it performs. This trip *was* going to be combined with a trip to Star for a remap...but because of this problem...I have postponed, yet again.

Question....

What are the symptoms of a knackered turbo and/or wastegate?

Just seem to be able to really hear the turbo spool-up these days.

Cheers

AL

 

[Ryanc]

log n75 duty ,actual,requested boost.

 

[AL_B]

No probs Ryan. Not logged N75 duty for a while. But have recently logged actual vs requested.

I will do it again though. I remember them being pretty close. But in a 3rd gear pull, boost didn't seem to be smooth as the revs climbed.

 

[Ryanc]

should be no more than 95%

 

[scubadood]

Looks like the 2l tdi is getting a Recall because of this. Any one know the details? Its on teletext (page 510- i think)

 

[AL_B]

At work at the moment, can you remember what the teletext page said?

 

[scubadood]

no, my father read it ou to me all A3s between 03 and end of 04 2TDIs. 70k through out europe

 

[scubadood]

Audi recalls 70,000 A3 cars due to clutch fault

Reuters
Automotive News / February 17, 2006 - 12:00 pm


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Advertisement


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FRANKFURT -- Audi is recalling around 70,000 of its A3 cars worldwide because of possible clutch faults, the company said on Friday.

A spokesman for Audi, Volkswagen's premium brand, said the affected vehicles had 2.0-liter diesel engines and were built between June 2003 and the end of 2004.

In some cases, the car would make clearly audible sounds and possibly come to a halt.

In Germany, around 20,000 vehicles would have to be recalled to Audi workshops for examination, he added. The company said owners of the affected cars should bring them to a workshop and leave them there for a day.

Audi said it would compensate the owners for any costs. The spokesman declined to comment on how high the costs could be.

Parent company Volkswagen had the same problem last year with some series of its Touareg and Golf models, a VW spokesman said. The faults had largely been rectified and new problems were not anticipated, he said.

VW and Audi buy some of their parts jointly.

 

[AL_B]

Thanks for finding that out.

The text is a bit vague though isn't it. Doesn't really say what the issue is...plus its regarding the A3 8P chassis, not 8L chassis.

AL

 

[AL_B]

[ QUOTE ]
should be no more than 95%

[/ QUOTE ]

Hi Ryan,

Did some logging on the way home, 94.5% is the maxiumum I have for the N75.

Didn't experience any hesitation today...but had some yesterday whilst cornering in 3rd gear.

AL

 

[dpeilow]

Hi guys,

Any updates on this thread? My issues have returned big style and I am going to start by getting Fountain to have a look at it.

Basically after checking things out on a Vag Com last year and finding nothing, then having a complete coilpack failure and replacement, I now have slippage and sometimes it feels like it isn't declutching properly. There is a bit of whine coming from somewhere too. I've got to get this fixed before it gets a remap and I take it to Le Mans.

Dave