Pulsing After Replacement Work

A

Andrew

A2OC Donor
England
Good Afternoon,

Nearly two weeks ago my mechanic worked on my FSI for 2 days, not cheap! The list of work included replacing all shock absorbers with the Bilstein B6 variant, timing belt refresh, A/C gas recharge and more pertinently I think replacement of pressed steel wishbones with cast (sorry forged) earlier versions. Note each cast wishbone came with connected consoles attached and replaced as a unit.

Rather wasted my money my old wishbones were in remarkably good condition after 20 years.

1720449205962.jpeg


Last Friday I went for the first proper test drive and detected what I can only describe as a subtle pulsing sat in the drivers seat. The frequency of the pulsing is just like a heart beat about every second and is quite disturbing/unpleasant. This pulsing is present at all times but is not speed related as I can feel it sat at traffic lights, feet off pedals.

I have an opinion about what is wrong and needs correcting but I will reserve it so as not to flavour any responses that but before I have words with my mechanic it would be good to hear what others think.

Thanks, Andy
 
Andrew said:
Good Afternoon,

Nearly two weeks ago my mechanic worked on my FSI for 2 days, not cheap! The list of work included replacing all shock absorbers with the Bilstein B6 variant, timing belt refresh, A/C gas recharge and more pertinently I think replacement of pressed steel wishbones with cast (sorry forged) earlier versions. Note each cast wishbone came with connected consoles attached and replaced as a unit.

Rather wasted my money my old wishbones were in remarkably good condition after 20 years.

View attachment 125632

Last Friday I went for the first proper test drive and detected what I can only describe as a subtle pulsing sat in the drivers seat. The frequency of the pulsing is just like a heart beat about every second and is quite disturbing/unpleasant. This pulsing is present at all times but is not speed related as I can feel it sat at traffic lights, feet off pedals.

I have an opinion about what is wrong and needs correcting but I will reserve it so as not to flavour any responses that but before I have words with my mechanic it would be good to hear what others think.

Thanks, Andy
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For once, I have no ideas, not even wild ones.
Mac.
 
Is it related to engine speed, you say it’s present when the car is stationary and idling, but does it speed up with higher revs?
The first thing to do would be to determine if it’s engine related or not.
 
Indi said:
Is it related to engine speed, you say it’s present when the car is stationary and idling, but does it speed up with higher revs?
The first thing to do would be to determine if it’s engine related or not.
Click to expand...
Good Evening,

I think not but will check just seemed continuous.

Thanks for the thought.

Andy
 
Andrew said:
Would a timing belt one tooth out do that?
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Timing belt a tooth out on my FSI did not. The FSI has variable valve timing, which will automatically compensate for small timing differences. There will be no difference (and I believe even the ECU won’t be able to tell) until it tries to adjust the vvt to an extreme and then realises it can’t quite reach the timing offset it’s looking for.
 
Not hunting no that's more related to air leaks allowing unmetered air into the mixture. A tooth out on the timing I would expect a engine mil and the engine to run "fluffy"
 
Howey said:
Not hunting no that's more related to air leaks allowing unmetered air into the mixture. A tooth out on the timing I would expect a engine mil and the engine to run "fluffy"
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From my experience with my fsi it was not super noticeable apart from occasionally a weird shudder/ popping when idling and cold immediately after start up.
Eml lit up after 100 miles or so.
 
In-tank pump starting up and stopping, as if it was detecting an open driver's door but then realising that the engine was already going?
 
PlasticMac said:
A poorly secured ARB, vibrating at it's natural resonant frequency, 1Hz.
Mac.
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Good Evening Mac,

You may be on to something there, much better than the lumbar suggestion. I asked my mechanic to replace the ARB bushes with bushes I provided but much to my annoyance they were the wrong size. I did know there are two sizes but never thought to check when I ordered, early signs of Alzheimer's?, I should not joke really. Anyway he said the existing bushes were fine and reused them along with the new bolts I provided so the ARB was loose at some point but I don't know know about torque used but if anything they will be over tight. He seems to use two settings, finger tight and 300Nm, you try getting the wheels bolts off after he has tightened them, I have to use a 2 foot breakers bar with an extension! I did challenge him once and his response was along the lines of ' when I tighten something it stays done up'.

Andy
 
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Hi Andy,

I think that it is fuel pump related, electric or mechanical with preference on the former. Maybe check the pressure and look for the pulsing that you describe.

Evros
 
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