Strange engine vibration....

[rusty1]

Hi all, this is my first post on here but I’ve been a spectator for a while and I’m hoping for some advise.
I’ve got an A3 1.8 sport and when the rev’s get to about 3k – 3.5k the engine vibrates quite bad, I can feel the vibration through the floor and pedals.
Any idea's anyone, as I’m running out of options.

 

[rusty1]

I should add it's been serviced and had the oil, plugs, leads, air filter replaced but made no improvement.
Vagcom shows no faults and the maf, lamba sensor's working ok.
I get good fuel ecomony and performance.
It does pop out of the exhaust sometimes after reving it so I thought it could be the cat?

 

[IIIadidasboy]

Where did you have it serviced - I'd take it back and ask them to try and explain. If they don't know, get your money back and ask someone on here for recommendations for a good service centre local to where you are.

Does it only vibrate between 3-3.5k revs, or is that where it starts and then goes all the way to red-line? Does it only do it when you're on the move or also when you're stationary? If your performance is unaffected then it could be something silly like engine mounts?

 

[marcyp]

that is your enigne code as it mabye be the vv-t acting up, also how many miles has your car done as it may be enigne mount being warn, other thing is it doing it all the time i.e. when the enigne is hot and cold or only when cold?

 

[rusty1]

Thanks for the reply,

A friend who own's a specialist garage serviced it for me, but he's as unsure as I am.

Like I said, it runs great now after the service apart from this odd vibration. Which was there before the service and only happens between 3-3.5k when the engine's hot, moving or stationary, worse in 4th and 5th.

It also pinks under load as well as pops out the exhaust sometimes. But rev's through to the red line after 3.5k no problem.

I've checked the engine mounts and replaced the lower rear but this hasn't helped.

It's an AGN on 100k, cam belt was changed at 80k.

I've thought of a few things it could be ie coil pack, throttle body, timing, Maf, cat etc. But nothing on Vag com.

but I was hoping to narrow it down, rather than throwing loads of money at it.

Any idea's are very welcome

 

[IIIadidasboy]

If it's only doing it between 3-3.5K rpm, then maybe air or maf related?

[edit] sorry just realised that it's not a turbo - so maybe my suggestion's not right (I was thinking hose colapsing or something air-fuel mixing ratio(maf))

I'm sure someone here will be able to come up with something though

 

[Dani_B19]

So you've checked all the engine mounts for wear? You also checked the dogbone mount bush?

 

[RichA3Turbo]

If its only at those revs, then it sounds like something is off balance. has it always done this/only just started doing it suddenly/progressively got worse?

When i had the dual mass flywheel in, mine would vibrate at around 3kRPM on the overrun..since going single mass lightweight, this no longer happens

 

[rusty1]

Yeah, I've checked the engine mounts and it was the dogbone mount that I changed, but no difference.

It's progessively got worse. I had a Milltek system fitted which was too loud at motorway speeds, so I changed back to standard. Then I could hear it as well as feel it.

It's as if the timing isn't advancing at the right time or is slightly out but I'm not sure how to check that, the haynes manual is of no help. Vag com says it's at 9*btdc.

 

[marcyp]

could be that when you changed the system back to standerd sumthink isnt clearing propely i would check the system first making sure its hanging in the right places and not tuching anything as it might be at that is all it could be

 

[rusty1]

I changed the exhaust over myself in my mates workshop, had it up on a lift to make it earier. New OE parts, it went together no problem and had plenty of clearance.

Altho the cat didn't look to great, I was wondering what the symtoms would be if the cat was breaking or broken up inside?

 

[wibble111]

I changed the exhaust over myself in my mates workshop, had it up on a lift to make it earier. New OE parts, it went together no problem and had plenty of clearance.

Altho the cat didn't look to great, I was wondering what the symtoms would be if the cat was breaking or broken up inside?

Not too sure but i would have thought vag com would show a fault if it was the cat from the post cat lamda

 

[rusty1]

I only have 1 lamda sensor, before the cat. I think this is cos it's an AGN non-turbo engine.

So vag com cant tell much about the condition of the cat......

 

[kip]

I have this symptom too. Can notice it 4/5 gear around 3000 rpm mark up wards. Their is a noticeable shimmering felt through clutch and accelerator pedals. I could never get to the bottom of it. Some days it's noticeable, other days it seems not so bad. I too say it might be a worn engine mount or something like duel mass flywheel or even a out of balance drive shaft. If you ever sort it out post it here mate. Like ways I will do the same but have lived with it and hopefully no damage comes from it.