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Discussion Starter #1
It started at just under 79,000km engine shaking when slowing down or idling with check engine light flashing or solid.

1st visit to Audi dealer ->
codes P0300, P0301, P0302, P0303
They took a long time to perform their diagnostic steps but finally decided that a carbon cleaning might fix it, since I think they you;don't determine the cause. $1000 later I got my car back and it seems ok. But it was shaking a bit whenever I started up.

A couple days later the problem reappeared (shaking a lot on slow speed or idle and check engine light).

2nd Visit to Audi dealer ->
Came back with same codes -> P0300, P0301, P0302, P0303 + new code P2177
They spent more time diagnosing and found purge valve wasn't working correctly.

I authorized the repair (quoted cost $450) and they replaced the valve but then I never heard back from them. I called back and they said their fix didn't work and now they are trying other things to determine the cause including possible looking into the cylinders to see if there is any scoring using a scope.

Does anyone have any advice on this matter?
I'm kind of worried they can't fix it. Luckily I'm not paying for the extended diagnosis time since they failed to fix it twice. Audi Canada also reimbursed me for $200 which helps a bit but I feel a larger repair bill on the way.

Audi A5 2010 2.0T
 

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Try another dealer, first suggestion. Or better find a VW/Audi specialist that know what they are doing and use VAGCOM. Good luck!
 

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+1 for trying somewhere else. Dealers seem to be rather shit at diagnosing anything.
 

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Discussion Starter #4
I'm not opposed to taking it elsewhere, the only reason I brought it to the dealer where I bought the car is that I have that extended warranty for the fuel injectors which would cause these misfires. If it turns out to be faulty fuel injectors I have to take it to an Audi dealer anyway to get Audi Canada to pay for the repair under the warranty. I feel like I'm being held hostage because of that though.

If I tow the car to an specialty mechanic and they find the issue is the fuel injectors, then I have to get it towed back to the dealer again....that's going to cost $$$ for towing + diagnosis time at the other place.

Do you think it would be apparent by now if there is faulty fuel injectors all this time?
 

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Dunno how the injectors could cause this kind of behaviour to be honest. And the carbon cleaning was a very expensive red herring so I would get my car to someone who knows what they are doing quick!!!
 

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You need VCDS !

I would start by looking at fuel trims. I had a 3.2 that was crap at idle, under load it seemed fine. Lift off and brake to a stop the engine started shaking and it narrowly avoided a stall, engine light would then come on for the misfires.
My fuel trims were -25 bank 1 -30 bank 2. I had 4 bad injectors that were leaking (not turning off fully like a leaking tap at home, drip drip drip)
Your problem could be leaking injectors, an air leak of sorts, or, really bad carbon build up.

If you are not technical, pay a dealer or VAG specialist for a diagnosis. It should be a hours labor. At the result if they cannot provide evidence to support the diagnosis they are guessing period. These problems are not hard to solve for a person that knows what they are doing, your problem is finding such a person.

The plastic intake manifold that you will have on a 2010 FSI also tends to warp creating a vacuum leak at idle - a bad leak you should hear. A smoke machine will find this in 10 minutes - any diag. of your symptoms must include a smoke test. If they sound wishy-washy at recommendation time (spend your money time) go somewhere else an pay for a second diag.....its much cheaper than loading up the parts cannon.

To answer your direct question, is check your injectors for leaks is also really easy. Have VCDS monitor the fuel rail pressure, turn off car, rail pressure should stay above 20bar for 20 minutes, if it does not remove spark plugs and bore scope looking for puddles of fuel on pistons or clean heads of the injectors (good injectors are all black, leaking ones are clean and you see the stainless steel). Its all really easy, you just need to find the right people.

Good luck and I hope you get this cleared up.





Once you find a good mechanic hold onto them, they are rear.
 

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Discussion Starter #7
Replacing fuel injectors had no effect.

Is bad fuel a possibility? Although I only fill with 91 octane, maybe there was some contaminant in the tanks at the gas station I filled up at?

I was told they might remove the existing fuel. Seems like they've exhausted all other of the most common possibilities.
 

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Miss fire codes and a lean code.......you have unmetered air getting into the cylinders......vacuum leak. Does it go away when you are under load and the turbo will be boosting ?

Once you get this fixed after they peg enough darts at the board to fix it by luck never go back, they have no pride about their technicians.

90% its a vacuum leak.

Does it changes between car hot and cold ? - vacuum leaks that are just starting tend to do this. Usually disrepair when hot.

Good luck - I hope your not paying fir it.

If it turns out to be a vacuum leak - all they needed to do right from the get go was graph the fuel trims while going for a drive, bad fuel trim no load, ok fuel trim loaded, means go back to the shop and hook up the smoke machine, see smoke....diag. done. They will be this years front runners for the golden spanner award.
 

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I get the impression that you are asking the questions and then not reading the excellent responses, why????? You have let them charge you a fortune for a carbon clean which was money down the drain, now you want the problem to be the injectors cos you have some spare, but it seems to me the solution is obvious and you continue to look elsewhere........wierd.
 

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Discussion Starter #10 (Edited)
I get the impression that you are asking the questions and then not reading the excellent responses, why????? You have let them charge you a fortune for a carbon clean which was money down the drain, now you want the problem to be the injectors cos you have some spare, but it seems to me the solution is obvious and you continue to look elsewhere........wierd.
I am reading them and the responses are useful to me as a check, to keep an eye on them and verify if the repairs they want to do make sense or not.

However the repair itself is not under my control. I am not a mechanic but the car owner. The carbon cleaning I let them do because I believed them when they said it would fix the problem. After it did not I became suspicious and came onto the forums. I really don't have the technical knowledge, but from the warranty letter I have about the possible faulty fuel injectors cause misfire it was just a suspicion that I wanted them to check in case it was true, they would replace them at no cost under the warranty. Obviously this is not the problem, since they went ahead and replace them anyway and it still didn't fix the issue.

I mean I feel its not my job to tell them what the problem could be even if I found out from you guys or even on my own. The reason is that they are an Audi dealer and should have the best equipment and knowledge of these vehicles. They should be skilled enough to find the problem on their own.

Luckily I'm not being charged for this extra time since it is their failure to diagnose. That is my only reason for leaving it there, other wise taking it to a third party shop will cost way more since they have to start the diagnosis from scratch.

What do you think? Should I provide them with the suggestions from this forum? They may or might not even listen to me. Maybe they did those tests already. But from what they told me so far they did not run those suggested tests yet (the ones posted by IDUA_5A) I will try and find out for sure.
 

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Er well GO SOMEWHERE ELSE!!!!!!!

They obviously dont know what the hell they are doing. You own the car. You have the right to go where you want cos you pay the money.

Is that clear?? Is there something you do not understand??? Many main dealers are awful, unfortunately, some are surely good.

Take the car and find a good dealer or better a good INDEPENDENT service man. Period.
 

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Could be yes....

Could this not be coil packs?
It could be anything. You need a competent service guy with time to work thro all of the possibilities and eliminate them one by one. Otherwise we just stab in the dark!!
 

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On balance, I reckon IDUA_5A has the right of it - sounds like a vacuum leak. I think you’d be well advised to spend the time finding a more competent garage. Where are you based in Canada?
 

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I reckon the guys working in the dealership have some sort of permanent brain damage if they cant figure out what went wrong with the car after they have had it for this long... I remember when my old fiat's ecu gave up it was throwing all sorts of codes out, i changed throttle valve, accelerator pedal, spent weeks trying to figure out what the hell it was after taking it for diag into one garage and in the end it just died and i couldnt even drive it, so took it to one recommended guy and he said to me as soon as i arrived that most likely it will be ecu, two days later the car was as good as new.
You just need to find reputable guy who will look after you
 

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Discussion Starter #16 (Edited)
Ok first of all I think this situation is a bit strange in that every time they release the car to me it passes their tests, and it runs fine for a day or two but then the problem slowly starts to manifest itself. So please, telling me to just take it somewhere else or insulting the service tech's intelligence is really not constructive. I'd appreciate some other suggestions as to what might cause that particular behaviour (from fine for a few days to slowly building up to engine misfires and shaking). And yes I think they have checked most or all of the items that have been suggested above (see to the end for summary of service). If they missed something please indicate.

To update the story, the main parts that have been repaired are carbon cleaning of intake runners/valves, replace faulty purge valve, replace all fuel injectors. They also proceeded to empty all the fuel from the vehicle and replaced it with new premium fuel. Because they suspected bad fuel having exhausted all other possibilities.

After they did this the vehicle ran fine. They took it for an extended road test over the weekend to test under day to day driving conditions with their computers attached. and it was running fine, no fault codes or engine misfires.

They released the vehicle to me and it was running better than it had ever been. I could actually feel the difference when pressing foot on the gas to accelerate. (i'm guessing the new fuel injectors together with the carbon cleaning helped with that)

BUT a day or two later, I noticed the shaking start up. First it was very faint, nothing like I felt the first time I brought it in. Yesterday on my way to work the check engine light started flashing for 10 seconds and go out with intermittent shakiness while driving. I parked my car and left it for the day, when I finished work and returned to the parking garage to go home, I turned the vehicle on and the check engine light remained illuminated. I drove it back to the dealer so they can extract the new fault codes.

Still waiting on that 'cause they are closed over the weekend.

SUMMARY OF SERVICE (from the beginning)
- road test to confirm issue, found vehicle idles very rough
- connect battery maintainer and scan for faults - found P0300, P0301, P0302, P0303
- monitor misfires - found cylinder 1 to be worst with most misfires counted
- removed and inspected spark plugs
- swapped ignition coils and spark plugs
- ran vehicle and found no change with misfire conditions
- performed compression test - no faults found
- performed cylinder leak down test - no faults found
- ran vehicle to operating temp and monitored fuel pressure with vehicle off - pressure would rise and stay steady
- inspected operation of variable intake runner flaps - no faults found
- removed air intake and found intake runners and valves to be covered in carbon deposits
- cleaned carbon from intake and reassembled
- performed road test and reset readiness monitors
- vehicle ok - delivered vehicle to customer
- vehicle returned with same symptoms
- rescanned faults and found same misfire codes with additional P2177 - system too lean
- inspected evap purge valve - found to be not holding vacuum
- removed and replaced purge valve and cleared faults
- performed road test and rescanned for faults
- vehicle is running better - misfire less frequent but rough running and misfires still persist.
- remove intake manifold and replace all 4 fuel injectors
- remove and replace all fuel
- clear faults and perform road test - vehicle ok
- inspected for leaks, no leaks found
- performed extended road test and both hot and cold starts
- vehicle now operating to Audi specs
- vehicle delivered to customer

- vehicle returned three days later - check engine light solid, intermittent shaking
 

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Ero, it may be that you don’t find the advice to take the car to someone else constructive. However, that doesn’t mean it’s not a reasonable piece of advice. I agree that bad-mouthing the mechanics probably isn’t useful. Even so, it’s clear from what you’ve recorded here that whatever is wrong with the car is beyond the ability of the garage to trace and rectify. Under the circumstances, a fresh set of eyes, and a different approach, may be exactly what you need to get this problem sorted.
 

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Discussion Starter #18
Ero, it may be that you don’t find the advice to take the car to someone else constructive. However, that doesn’t mean it’s not a reasonable piece of advice. I agree that bad-mouthing the mechanics probably isn’t useful. Even so, it’s clear from what you’ve recorded here that whatever is wrong with the car is beyond the ability of the garage to trace and rectify. Under the circumstances, a fresh set of eyes, and a different approach, may be exactly what you need to get this problem sorted.
In a way I agree, however you can't totally place fault on them for not finding the issue already. It's like the car is toying with them. I mean it works perfectly fine at the end of each service cycle and gets released back to me. I think thats the main problem here which is causing such a long repair time, and probably contributing to them mistaking each repair for the actual correct one that will fix the issue permanently, because in a way what the've done 'appears' to fix it.

If the problem were to persist continuously, then this would be a whole lot easier and they might have greater chance of determining the fault faster. But thats not the case here.

In any case I'll see what fault codes I get this time and go from there.
 

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Discussion Starter #20 (Edited)
Well my car is still not fixed and its back in service, this is 4th time. Is this considered a lemon? Too bad we don't have those lemon law like in the US.

So just as an update, along with the fuel injectors, they also replaced the fuel, but it wasn't the fuel obviously because it happened again right after using new premium fuel.

During the third visit the main part replaced was the PCV valve.
After that when I drove the car, it was driving normally for 3 days. I thought it was fixed for good, no shaking whatsoever or check engine light.

But today all of a sudden after work I was driving home and I could feel it building up, then it started up all of a sudden while idling in traffic and at stop lights. I almost didn't make it back to the dealer, the shaking was worse than the first time and I pulled over to the side of the road at one point. I had to drive really slow at first (couldn't accelerate too much due to the rough feel of the engine) but after it stabilized a little I was able to accelerate normally which only lasted until I came to the next stop light at which point the rough shakiness started again.

This time in addition to the flashing check engine light, the EPC light also came on.

Is this still a symptom of a vacuum leak? I.e. working fine for about 3 days each time then building up until it fails all of a sudden?

It doesn't even fail gradually over those days...it just happens all of a sudden during the last drive shortly after taking off.
 
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