polaraudi

Is that because of the issues you were having, or is that their philosophy in general? I'm curious partly because I can only find 90 octane in my area, not the 91 the manual recommends, and it's been worrying me a bit.

CrownSeven

I've read that premium is recommended because it helps alleviate potential carbon build up on FSI motors - although not sure how true that is.

runbird13

The vehicle was left at the dealership yesterday and a follow-up consultation with the service manager (SM) occurred today. The fuel injector on cylinder number 4 is leaking. This is the first appearance of leaking injector problem for this service department. Audi has been called in to oversee (and approve) the repair. The SM advised that the problem was likely “caught early enough” to head off any long term problems. Obviously, a major concern would involve fuel leaking down and mixing with and diluting the engine oil.

Admittedly, I am not totally at ease with the long term prognostication, but glad to see the problem was identified quickly. One last note, cylinder 4 injector is the only one that shows obvious leaking, but SM indicated that it is foreseeable that overall repair process might involve some “trial and error” to identify other possible leaking injectors.

The G Man

Leaking fuel injector should not cause any longer term damage. As far as I know, a leaky fuel injector should not cause gas to get into the oil. A leaky fuel injector usually cause an engine to start up rough, run rough or it might cause problem starting. I suppose if the problem isn't fix, it can foul up the injectors and the valves over time. This is not a new problem with Audi, there is a TSB for injectors from other Audis with the same engine. Got to love it when the service people say, this is the 1st time I have seem this problem

runbird13

Thanks for sharing the positive thoughts, G man. I am definitely hopeful that no long term problems will surface. One of the first questions that one of the techs asked me during the diagnostics process was whether the check engine oil alarm had triggered at any time. Their primary concern was that excess fuel would fill up in the affected cylinder and then begin to leak past rings and dilute the oil. They saw no evidence of this when the oil was changed as part of the service.

Admittedly, I am no expert on direct fuel injection technology, but I thought I would share the dialogue between owner and SM. As with you, I find it humorous that all problems that surface with vehicles are apparently unique and have never before been seen. It's a bit like that demo car that was driven by the owner's wife. Parts are on order and the vehicle should be home by early next week. I'll update if anything interesting transpires.

The G Man

runbird13, the piston rings should seal pretty tight, if any oil could leak thru there, it should be very minimal over a very long period of time. If The piston rings are not seal properly, you would have other very serious issues such as low combusion.
I just had 3 injectors replace in my 2008 A6, there was carbon built up in the injectors as well as behind the valves. I am not sure if the build up is related to the leaky injectors, but everytime I start the engine in the morning, I would get misfires due to the cylinders being flooded, the CEL is also on sometimes. The Audi mechanic tells me that he replace a lot of injectors, coils and do a lot of carbon cleaning on the Audi 3.2L engine as well as the S4 and the S6.

runbird13

The leaking injector has been replaced / repaired. This should remedy the ignition problems, as well as engine power deficiencies. During the diagnostics, the tech concluded that enough fuel was leaking to drown the spark plug causing misfires or no firing at all, inhibiting optimized combustion.

Further, I am delighted to report that a hesitation that I have noticed when accelerating from stop seems to have disappeared. Since delivery, I was unsure if it was just a perceived hesitation or if the vehicle was operating as designed, but I became convinced that a problem existed the first time I drove the loaner which did not exhibit this hesitation. The Service Manager advised me that the tech did recognize / experience the hesitation during diagnostic test drives. He speculates that it was related to the fuel injector problem.

I will report back after a few thousand miles or if any symptoms resurface.

runbird13

I experienced misfiring or ignition failures again last week. The vehicle went in for out of schedule service and it was discovered that the fuel injector in cylinder number 6 had failed. Permission was sought and approved by AoA to replace all five remaining injectors not addressed during 5k service/repair. The Service Manager made remarks that seemed to reinforce comments that I have seen on this forum and others that a bad batch of injectors were received from suppliers and installed in Q5s with build dates sometime in the Fall 2010. Besides misfiring, other symptoms of this problem include strong fuel odor emitting from leaking injectors that will fill cyclinders even after engine shut-off and less than optimal fuel mileage performance.

Reggie

I would think the problems it would cause is washing of the rings and possible wear - as well as dissolution of the oil with gas

tmick13

It also would cause the piston rings to be worn or even break.