Engine help - poss fuel starvation and a rattle.
Discussion
I've posted this in the S6 forum as well but just in case anyone else can help;
I picked my car up from her 12k service today and all was well until I went to do an overtake. I was at 40mph so dropped into 2nd, pulled out and put my foot down only to almost be forced into my seatbelt with a sudden lurch and loss of power, almost as if the engine had just seized. Pulled back, and carried on and all was fine. Done it a couple of times now but unfortunately my mechanic had now gone home - could it possibly be a fuel starvation issue? It idles fine and runs perfectly when being pootled around on medium to light throttle and even then this fault doesn't happen every time I put my foot on the floor.
2nd issue I have is a tick/rattle that sounds a little like one of those old football rattles (like a flag that you spin round holding the handle), can hear it from 1500rpm up and right through the rev range, definitely the engine as it does it when not moving as well. Again, I've stopped the car and restarted and the noise was gone. It's fairly loud and I can hear it quite audibly over the engine.
Obviously I'll be ringing my garage for help on Monday but in the meantime do any of these faults seem familiar to you or do you have any ideas?
I picked my car up from her 12k service today and all was well until I went to do an overtake. I was at 40mph so dropped into 2nd, pulled out and put my foot down only to almost be forced into my seatbelt with a sudden lurch and loss of power, almost as if the engine had just seized. Pulled back, and carried on and all was fine. Done it a couple of times now but unfortunately my mechanic had now gone home - could it possibly be a fuel starvation issue? It idles fine and runs perfectly when being pootled around on medium to light throttle and even then this fault doesn't happen every time I put my foot on the floor.
2nd issue I have is a tick/rattle that sounds a little like one of those old football rattles (like a flag that you spin round holding the handle), can hear it from 1500rpm up and right through the rev range, definitely the engine as it does it when not moving as well. Again, I've stopped the car and restarted and the noise was gone. It's fairly loud and I can hear it quite audibly over the engine.
Obviously I'll be ringing my garage for help on Monday but in the meantime do any of these faults seem familiar to you or do you have any ideas?
tail slide said:
Sounds very like a follower shim has jumped out to me, exactly same symptoms
I had a few years ago on a new head build. If so, likely no other probs but don't drive it, you don't know where shim has fallen, what you don't want is it beng sucked into oil pump etc!
Sounds reasonable, but I'd expect much more noise (I'm guessing the rattle isn't LOUD), and what about the wall he hit due to no power?I had a few years ago on a new head build. If so, likely no other probs but don't drive it, you don't know where shim has fallen, what you don't want is it beng sucked into oil pump etc!
Thanks guys! Whatever it is I'm not going to start her, unfortunately I've had to do about 160 miles today (no other choice unfortunately) so hopefully no damage. It may even turn out to be a simple explanation but a slipped shim I guess is possible.
I'll give my chap a call on Monday and ask for further help.
I'll give my chap a call on Monday and ask for further help.
Right then - further investigation in the cold light of day - the rattle seems to be a pulley on the air-con/alternator belt so my minds a lot more at rest on that one. It's the sudden cut/loss of power thats still concerning me. If an engine were to be starved of fuel suddenly would it cause a lurch as I've described above? As mentioned it only happens if I put my foot down rather than a gradual application of the loud pedal.
Zippee said:
Right then - further investigation in the cold light of day - the rattle seems to be a pulley on the air-con/alternator belt so my minds a lot more at rest on that one. It's the sudden cut/loss of power thats still concerning me. If an engine were to be starved of fuel suddenly would it cause a lurch as I've described above? As mentioned it only happens if I put my foot down rather than a gradual application of the loud pedal.
IMO a huge loss of power like you describe is more likely to be electrical - loss of spark. Whatever the case, get it checked by someone who isn't an Internet warrier.Targarama said:
IMO a huge loss of power like you describe is more likely to be electrical - loss of spark. Whatever the case, get it checked by someone who isn't an Internet warrier.
Warrior or Worrier? 
In my experience always useful to have a few known possibilities to take to a garage, as many mechanics have strong opinions which can make them overlook real causes of faults.
I'm pretty sure it has been known for shims to move in and out of position slightly, but of course unlikely to find for sure without a good checkover.
Edited by tail slide on Sunday 13th June 17:10
Zippee said:
Thanks guys! Whatever it is I'm not going to start her, unfortunately I've had to do about 160 miles today (no other choice unfortunately) so hopefully no damage. It may even turn out to be a simple explanation but a slipped shim I guess is possible.
I'll give my chap a call on Monday and ask for further help.
12k service inc fuel filter change right? poss trapped line or damaged/blocked filter. Could also be a plug(s) issue as the cam cover leads/plugs have been out.I'll give my chap a call on Monday and ask for further help.
tail slide said:
Targarama said:
IMO a huge loss of power like you describe is more likely to be electrical - loss of spark. Whatever the case, get it checked by someone who isn't an Internet warrier.
Warrior or Worrier? In my experience always useful to have a few known possibilities to take to a garage, as many mechanics have strong opinions which can make them overlook real causes of faults.
I'm pretty sure it has been known for shims to move in and out of position slightly, but of course unlikely to find for sure without a good checkover.
Edited by tail slide on Sunday 13th June 17:10
I friend's S6 lost shim on his brand new T350, it tapped VERY loudly.
Shep's theory is another bossipility of course.
s6boy said:
Targarama said:
IMO a huge loss of power like you describe is more likely to be electrical - loss of spark. Whatever the case, get it checked by someone who isn't an Internet warrier.
sounds like a perfect example of a coil or lead breaking down.s6boy said:
Smart bloke that Matt. Taught him all he knows 
you know - Matt was only saying this morning jus how indebted he is to you john BTW if you're free one saturday in july do you fancy a run out? Would be nice to catch up properly. Iirc flintstone is also reasonably close so we can see how quick powers 4.3 really is.
Probably barking up the wrong tree but...I had a 16v Passat that did this, everytime you pulled away hard or floored it in a low gear it just died. It turned out to be a split in the corrugated intake pipe - the metering unit was mounted on the bulkhead so when the engine moved a lot the split opened and it got a big lungful of unexpected fresh air. Maybe something similar is happening with connectors or sensors?
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