Strange Power Problem

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cybrey

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My t-Sport has developed a strange power problem.

It normally occurs if your on boost and you let the revs dip below the boost level and then you try and accelerate hard the power just cuts out completely for a second.

For example yesterday going around a round about in 2nd / 3rd, came off the acelerator, at the start of the slip road onto the motorway put my footdown and the cars power went completly for a second and then came straight back in at full. It feels like when you slip the clutch at lights by accident you get the jolting sensation.

Anyone come across / resolved a similar problem ?
 
Had the same thing on my S3 since about 6 months from brand new. Do a search for hesitation.

I have gone through:-

1) New OEM DV. Also tried Forge DV006 & 007
2) Coil packs
3) AMM/MAF
4) Spark plugs
5) and the latest: new N249 valve (not sure if you have this on your A3). I also had a hole in a vacuum hose going to the N249, had this replaced too.

At the moment, I have no hesitation in on-off-backon throttle situations in a straight line, but it has occurred briefly when cornering and giving it full throttle out of the bend (with ESP off).

I also still get a surging feeling on light throttle loads.

So quite similar to your car perhaps.

Anyone else got any ideas of what next to try?

AL
 
The surging on light throttle sounds like the Oxygen sensor (lambda sensor)
A faulty or slow lamda sensor can also give a short hesitation when acclererating.
Does it use more fuel than normal?
 
AL-B That sounds exactly like the problem I'm having even down to the cornering bit. ( ie going round a round-about).

Martin S - I don't think mine uses any more fuel than normal, it gets around about 31mpg with normal driving, and about 35 on a motorways stint.
 
Didn't know how to describe the 'hesitation' problem yesterday so couldn't search just did one now and it seems the majority of the ol' timers on here are having / had the exact same problem. Only trouble is none of them posted a solution, which doesn't bode well.

My first thoughts were a collapsed pipe or a hole but I would have thought this would do this nearer the top end ie 4500+ not nearer 2500 / 3000. I thought about a faulty MAF but I've only read about consistent/repeatable problems with this.. not something that happens once in a blue moon and under strange circumstances ( like the cornering thing, although that could be that we all corner in second at a similar speed).
 
I've had similar problems and just had a new Throttle body installed to "Test" this morning. It immediately cured the erratic idle (so far /ubbthreads/images/graemlins/crazy.gif) but traffic was bad so I won't be able to fully test it until tonight. I'll keep y'all updated in case it might help /ubbthreads/images/graemlins/beerchug.gif
 
Martin S - Thanks for the tip mate. I will see what the dealer thinks about it ( I have a good relationship with them). However, my car was only in with the dealers last week, and no fault codes were reported regarding the Lambda sensor.

Cybrey - Its good to know others have the same problem isn't it. But like you say, no one has found a definitive solution yet.

I was also thinking about "could it be the collapsing pipe problem", but if that was the case, why doesn't it do it in a straight line.

I was also thinking.... because this is happening on a bend...could it be a loose electrical connection, or perhaps fuel/oil starvation? I'm sure I heard something on the TT forum once saying it could also be the car battery? I don't know if any of those are possibilities or not.

The problem is so intermittant now, its going to be very hard to pin-point.

Cheers

AL
 
Guys,

Maybe an idea to add to the mix...take a read on my story.

I have a 1.8TQ car and at 19 months old the cars engine management light came on. Called audi assist out, they troubleshooted and said it was a common problem of a dirty throttle body. Under normal driving the car was fine...however ever since owning the car from 17 months old, occassionally especially in on off boost usually second gear demand situations it would loose all boost temporarily giving a real jerk to the car. Obviously when this happened i usually throttled off and then instantly back on again and power was there no problem.

The cleaning of the throttle body did not cure this, but cured the management light (running to rich issue). However another 16 months went by and car continued to occasionally exhibit this symptom of sudden low down boost loss (about 2500 rpm)....although this could happen in a straight line as much as a corner situation.

Now....(here's hopefully the interesting bit)...the management light recently came back on again...car was however as usual driving fine 99% of the time. I thought immediately throttle body again, but thanks to the help of pure, i borrowed a VAG-COM and looked for faults before i thought about doing anything.

The car had logged faults of boost loss and running rich(idle) issues. I left the car running for a week or so and the light went off but the faults were still stored. About 2 weeks ago now, i decided to properly investigate and i took my dbw throttle body actually off the car. Pipe side of the throttle buttefly was fairly clean, however induction side was reasonably dirty and actually around the seating of the throttle butterfly there was also a build up of blackness!

I cleaned all this out with carb cleaner and fully reassembled. Also at the same time i put a brand new standard paper filter back in and cleaned the air box housing of any other crap. The upshot is the car is running fine, and now fingers crossed, 2 weeks of running my intermittent boost problem has gone. I think audi assist, only cleaned the pipe side when they came out 16 months ago and not induction side, and now that i have FULLY cleaned it the ECU is getting all parameters correctly responding.

Since doing this fix (and thanks to HTC and foolish for their advice) i've logged MAF, several times, checked the lambda values, and also logged block 115 for boost. Everything is giving consistent figures, so i seem to have eliminated my DV, MAF (AMM), pipes and lambda sensors as being issues......everything seems to have boiled down to a dirty throttle body and a nice clean air supply!

I'm continuing to monitor the car for faults, but it seems like they've gone away and now when i give it some welly it pulls good and hard, better than its ever done in almost 2 years of ownership. I think throttle body cleaning, is something i might do yearly from now on, just to be fully on top of the situation.

HTH

Evo
 
Will this apply to Drive by Cable cars as well ? ( excuse the ignorance /ubbthreads/images/graemlins/smile.gif )
 
audi upgrades
Boost leaks are surely more likely to happen consistently and at higher pressures than the ones we're talking about, also would they cause the car to have a complete loss of power or just a degration.
 
i would say that drive by cable cars could still be affected by this...in principle any crud near the throttle body is not going to help irrespective of how the throttle is driven. At least you could try a clean as a first step as i did since there's no cost to doing so...and then pursue other fixes. Also access to VAG-COM is a real help to see if the ECUs picking anything up.
 
Thats great information evotista!

So are you saying you cleaned both the flexible pipe side of the throttle body, and the induction manifold side?

If so is removal easy? Are there any gasket type seals which will need replacing on re-install of the throttle body?

Cheers

AL
 
Al,

Yes, i cleaned both sides of the throttle body. Removal wasn't that tricky....four allen bolts to remove, although access to the bottom left one needed a straight on screwdriver bit and not a classic allen key. Once removed the throttle body came away with a green induction side gasket still in place. I managed to reuse this with no apparent problems. Obviously i replaced the one shot usage type clips with some jubilee types.

Just set to it and you'll figure it out in 15 mins max. Once reassembled, at ignition switch on, you could hear the dbw readapt itself to get back to its new home position. I haven't gone to the trouble of disconnecting the battery to make the ECU totally readapt values, but it seems to be performing better than ever so i've left it alone for the time being.

Evo
 
so if you disconnect the batt, does that reset the throttle body position? i think i remember reading something about having to leave the ignition on for a set time. anyone???
 
[ QUOTE ]
so if you disconnect the batt, does that reset the throttle body position? i think i remember reading something about having to leave the ignition on for a set time. anyone???

[/ QUOTE ]

Disconnect the battery for 30 - 60 mins and this will reset the throttle body. Or use Vag-com, or try the ignition on for a couple of mins (but this is hit and miss!)

Rich.
 
regarding the boost leaks, it depends.

My car definately has a boost leak, you can hear it! It also exhibits the same symptoms as above.

If youve got a boost leak the car overfuels, the lambda sensor detects it and cuts the spark. Then everything returns back to normal and the car goes again. Turbo spools back up (here is where you get the power back) and after a while boost starts to leak again. The car again thinks its getting more air than it actually is (as the leak is after the MAF) and spark is cut again..;.

And the beat goes on!
 
Well guys I fitted my FMCL007P with green spring over the weekend. Unfortunately the car is still surging on part throttle.

So it looks like I will have to clean the throttle body as suggested above.

Just a comment about the FMCL007P. I've had this valve for a good 2 years or more, but don't run it as I feel the standard OEM DV reacts better in on-off-on throttle situations. And I still think that now.

Although, I would say the 007P does feel like its keeping closed better, and thus the car feels like its holding boost better. But the car feels more laggy when going from part-throttle to full-throttle, IMO. Thats how it feels to me anyway.

AL
 
OK, quick update on the new throttle body. I went in last week and spoke with the lead mechanic. We decided to go ahead and clean the old TB and return the new one. When the old TB was installed though..... the car ran even worse /ubbthreads/images/graemlins/frown.gif So we went ahead with the new TB. Everything ran nice and smooth for a couple of days, but now I'm getting hesitation again /ubbthreads/images/graemlins/crazy.gif Although the TB HAS cured the erratic idle (so far). I'm TRYING to get a Samco hose set w/ TIP so I'm hoping that that will clear up any potential boost leaks /ubbthreads/images/graemlins/crazy.gif

If anything changes, I'll post another update /ubbthreads/images/graemlins/cool.gif

/ubbthreads/images/graemlins/beerchug.gif
 
Yeah keep us posted.. I've not had any hesitation in 5 days now.. so maybe its gone away /ubbthreads/images/graemlins/smile.gif
 
TBH, I'm not even sure I've LOCATED the damned thing yet /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/angel.gif The only thing I can find that looks like it could be the N249 is located directly under the intake manifold (Under and to the right of the dipstick) /ubbthreads/images/graemlins/crazy.gif

IMG_0713.sized.jpg


/ubbthreads/images/graemlins/beerchug.gif
 
Seen that dude, thanks though. It appears that the N249 is in a different location on A3's /ubbthreads/images/graemlins/confused.gif (Or at least mine /ubbthreads/images/graemlins/crazy.gif) I think one of these weekends I'll trace the line from the DV back to see if it's where I think it is /ubbthreads/images/graemlins/angel.gif

/ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/beerchug.gif
 
[ QUOTE ]
Well guys I fitted my FMCL007P with green spring over the weekend. Unfortunately the car is still surging on part throttle.

So it looks like I will have to clean the throttle body as suggested above.

Just a comment about the FMCL007P. I've had this valve for a good 2 years or more, but don't run it as I feel the standard OEM DV reacts better in on-off-on throttle situations. And I still think that now.

Although, I would say the 007P does feel like its keeping closed better, and thus the car feels like its holding boost better. But the car feels more laggy when going from part-throttle to full-throttle, IMO. Thats how it feels to me anyway.

AL


[/ QUOTE ]

Al

I had major problems with the Forge 007P DV, the car was surging and not holding boost, i got refurbishment kits off them for it, they lasted about 3 days before i was surging again, i came too the conclusion that the Forge 007P DVs are a bad design i not worth the money you are paying for them.

I now have a AMD Viper DV and I have had no problems what so ever with it.
 
Yeah. I don't think this is a DV issue at all now. My Forge is like new, hardly used it. Checked it the other day, well oiled inside etc. too. So the surging is happening regardless of DV.

I'm thinking throttle body or throttle position sensor.

Do you ever get to a point were you are sick-to-death of these "little" problems?! There are so many components that "could" cause the same/similar problems - its bad design and poor quality on Audi's part IMO. Its p!ssin me off now.
 
Dude, I hear you /ubbthreads/images/graemlins/crazy.gif And what REALLY /ubbthreads/images/graemlins/swear.gif me off, is when the Audi service Techs want to get an attitude with you for troubleshooting stuff on your own /ubbthreads/images/graemlins/burningmad.gif

With mine, I suspected the N75, so I changed it with a (Known Good) F valve that I have. Well, things worked fine for a while, then back to surging and erratic idle. So I put the Original N75 back in. Well I did it while the engine was running, so naturally a fault was stored. So the Service tech tells my wife on the phone that they can't find the fault through the ones I've caused myself /ubbthreads/images/graemlins/swear.gif Needless to say.... we won't be asking THAT guy for anymore help /ubbthreads/images/graemlins/frown.gif (We talk to his boss now instead /ubbthreads/images/graemlins/angel.gif)
 
Thankfully my dealer is very very helpful.

Evotista,

When you took off your throttle body, did you disconnect everything...like the tube going to the top and any electrical connectors?

Just wondering if its just a simple plug everything back together, disconnect battery for 30mins, re-connect and away you go.

AL
 
Have you checked the small brake servo hose on the left at the front i had that go and i was having similar problems.
 
Al,

When i did my throttle clean, i did the following.

Engine off/ignition off and car cold
Removed throttle electrical connector
disconnected one shot use clip on the top pipe (breather pipe i think) and removed pipe
disconnected clip on intercooler pipe and removed pipe
Unscrew top two allen bolts and then bottom 2...on A3 getting to bottom LHS one was the hardest.....obviously this is different on an S3...since it's a different induction orientation

then give it a good clean away from the car

Put it all back with new jubilee clips.

I didn't disconnect the battery...but you might as well since this will force a full readaptation of all ECU values (since it'll forget its current learnt ones). Disconnecting battery is not necessary for dbw adaptation since i think the the loss of connection to the throttle is sensed and when you first switch ignition on afterwards you can hear the throttle go through it's adaptation routine......well at least it did with mine.

HTH

Martin
 
[ QUOTE ]
Have you checked the small brake servo hose on the left at the front i had that go and i was having similar problems.

[/ QUOTE ]

Andy, can you point out which one that is? Got a pic?

Martin, thanks for the steps mate. Job for the weekend.

Cheers AL
 
Hi m8

heres some links and pics of the hose. Its a small U shaped hose and u will need to remove it to inspect it properly, mine was split inside the U and i couldn't see it until i removed it.

waks web page

Replacement hose
web page


Some reason i cant upload pics but if u look on waks web page it shows you the hose im talking about go about half way down the page.
 
Ok, cleaned the throttle body today. Disconnected battery etc. So hopefully throttle body reset should have occurred - if the rumour is true about the ECU doing that when the battery is reconnected.

Car seems to idle ok. But not test drove it yet. So we will see tomorrow if the car still surges or not.

Got a question though. Is it normal for a fine wet covering of oil to be in the induction manifold, and for a small "puddle" of the stuff in the bottom of the throttle body? I also noticed that there was a fine covering in the IC2->TB pipe.

Cheers

AL
 
I asked the same question a while ago when noticing this in my IC hose. Apparently a fine coat is fine, especially if you've not noticed any increased oil consumption. But if it gets worse (or excessive) then it could mean $$$$ /ubbthreads/images/graemlins/crazy.gif

/ubbthreads/images/graemlins/beerchug.gif
 
Well, I have given it two days, and I'm sad to say cleaning the throttle body has not solved the surging problem. :-(

Also had a slight instance of hesitation this morning too, around 4000rpm. :-(

Not been able to check any other hoses (i.e. the 180deg bend one) for any leaks.

Personally I don't think it is leaking any boost, as with my foot to the floor in a straight line, performance feels pretty good. It's just this surging and the occasional hesitation especially round a bend.

Totally stuck now for what else to try.

Cheers

AL
 
Hey Al, I can't remember if it's ben asked before, but do you have any idea how they test the O2 sensors?? I seem to remember reading somewhere that it could cause hesitiation /ubbthreads/images/graemlins/confused.gif But how would we test it if the sensor's not COMPLETELY dead /ubbthreads/images/graemlins/crazy.gif

Just an idea /ubbthreads/images/graemlins/frown.gif

/ubbthreads/images/graemlins/beerchug.gif
 
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