Low knocking noise - any suggestions?

[Gtcpaul1971]

Hi,
My GTI has a low level knocking noise when the car is at bite point in 1st gear both forward and reverse. It disappears as the revs rise. It's when the revs are low and the car is at bite point. I can only describe it as a knocking/ rumbling noise. Worse when cold.
Any ideas guy's?
Cheers Paul

[pudding]

My ED30 is exactly the same, and has been for over 3 years without getting any worse. 

I asked this on the TFSI Tuning group facebook page a while ago.  A few people had the problem, but no one had any answers.

Weird thing is, with VCDS hooked up on the ignition timing channel, when the rumbling occurs....at 1000rpm....the ignition bounces all over the place.  It's almost like a 1000rpm limiter kicks in.

I had a Helix clutch put in a couple of years ago, along with a new DMF, no change.

Mine is also remapped and has uprated engine mounts, which doesn't help, but again, no change.

Just another odd ball quirk these cars can exhibit.  I'd love to get it sorted as it's been pissing me off in traffic for years!!  I just don't know what the fook it is though.

[Gtcpaul1971]

My ED30 is exactly the same, and has been for over 3 years without getting any worse. 

I asked this on the TFSI Tuning group facebook page a while ago.  A few people had the problem, but no one had any answers.

Weird thing is, with VCDS hooked up on the ignition timing channel, when the rumbling occurs....at 1000rpm....the ignition bounces all over the place.  It's almost like a 1000rpm limiter kicks in.

I had a Helix clutch put in a couple of years ago, along with a new DMF, no change.

Mine is also remapped and has uprated engine mounts, which doesn't help, but again, no change.

Just another odd ball quirk these cars can exhibit.  I'd love to get it sorted as it's been pissing me off in traffic for years!!  I just don't know what the fook it is though.

Hi buddy,
Thanks for that! Wondered if it was just my car lol. Well its having it investigated on Fri so if he finds anything I will let you know . Good to know it doesnt effect the running or is a message of impending doom. Always sounds like there is defo something wrong to me like 👍

[pudding]

Keep us posted mate!  My mechanic did have a listen a couple of times in the last few years, but didn't find anything conclusive.

To me, it sounds and feels like a dual mass flywheel rumbling before it's fully loaded up (clutch pedal released) or a slight clutch judder that's resonating through the dogbone mount, but not strong enough to feel on the pedal.   

I guess like mine, yours also doesn't have this problem if you hold the same revs with the clutch pedal up?  Only when it's down and taking up the bite?

[Gtcpaul1971]

Keep us posted mate!  My mechanic did have a listen a couple of times in the last few years, but didn't find anything conclusive.

To me, it sounds and feels like a dual mass flywheel rumbling before it's fully loaded up (clutch pedal released) or a slight clutch judder that's resonating through the dogbone mount, but not strong enough to feel on the pedal.   

I guess like mine, yours also doesn't have this problem if you hold the same revs with the clutch pedal up?  Only when it's down and taking up the bite?

Yes exactly, only when its down taking the bite - fooking thing! It is frustrating as hell as it sounds poorly.
There must be something wrong? That can't be right?
Funny you mentioned the mass fly wheel. Done a bit of digging and that comes up as a possible source. Would a fly wheel cause a knocking noise though?

[pudding]

Keep us posted mate!  My mechanic did have a listen a couple of times in the last few years, but didn't find anything conclusive.

To me, it sounds and feels like a dual mass flywheel rumbling before it's fully loaded up (clutch pedal released) or a slight clutch judder that's resonating through the dogbone mount, but not strong enough to feel on the pedal.   

I guess like mine, yours also doesn't have this problem if you hold the same revs with the clutch pedal up?  Only when it's down and taking up the bite?

Yes exactly, only when its down taking the bite - fooking thing! It is frustrating as hell as it sounds poorly.
There must be something wrong? That can't be right?
Funny you mentioned the mass fly wheel. Done a bit of digging and that comes up as a possible source. Would a fly wheel cause a knocking noise though?

Yeah it really gets on my nerves because it's mega sluggish to get moving as well! 

Defo not right, but thankfully it's not there when hot otherwise I'd get rid of the car tbh.......or convert it to DSG 

Yup, knackered DMFs can cause knocking......but the symptom for that is a very loud clattering at idle (all temps) that goes when you press the clutch down.

As I say, that rumbling has always been there on mine, stock clutch and DMF and Helix Clutch and new DMF.  Unless the new DMF is fooked, I'm fairly certain it's not a DMF issue.

One thing it could be is the dogbone mount.  Mine has had an uprated one (Vibratechnics) on it since I bought the car.  That has been the only constant during since owning the car and changing many things.  Is your dogbone standard?

[Gtcpaul1971]

I presume it is standard buddy, nothing has been done to it. The mechanic had a quick listen yesterday and his 1st thought was DMF . He is having another listen this morning from cold as I have left it with him. He did sit in the car and could hear it when the car was labouring at low revs. I just started to raise the clutch without any revs and it was pretty evident straight away. I am getting the timing chain done at VW Midlands  over Xmas while visiting parents so I'll get another opinion then. Strange it is difficult to identify.
Btw mine is also crappy when pulling away in low revs! Annoying! Surely we can't be the only ones to have this problem?

[pudding]

I suspect a lot of other people have the same issue, but either don't notice it or ignore it.   Let's see what Midland say!  I'm at AKS on the 14th, so I will ask them to have a listen to mine too.

Re: pulling away, there is a big torque jump at 1000rpm on the standard map, maybe to help get the car moving.   I've noticed on a lot of remaps that 1000rpm torque lift is removed, and as mine is remapped......   it does seem to corroborate with what I've seen on the live logging at that rpm...... it's trying restrict the rpm and feels like a traction control (deliberate) misfire.  Weird.

Another thing with mine, when the 1200rpm cold idle is engaged, it's a hell of a lot smoother, quieter and more eager to pull away.

[Gtcpaul1971]

I suspect a lot of other people have the same issue, but either don't notice it or ignore it.   Let's see what Midland say!  I'm at AKS on the 14th, so I will ask them to have a listen to mine too.

Re: pulling away, there is a big torque jump at 1000rpm on the standard map, maybe to help get the car moving.   I've noticed on a lot of remaps that 1000rpm torque lift is removed, and as mine is remapped......   it does seem to corroborate with what I've seen on the live logging at that rpm...... it's trying restrict the rpm and feels like a traction control (deliberate) misfire.  Weird.

Another thing with mine, when the 1200rpm cold idle is engaged, it's a hell of a lot smoother, quieter and more eager to pull away.

Funny you should mention the idle speed. Mine goes down to 800 rpm when cold and it struggles and sounds lumpy as if it needs more revs. Wandering if having the turbo pipe done today changes anything as it did have a hole in it so the air mixture would be wrong I guess.
Yes ask AKS as it is doing my head in. Also if you have had a new dmf I presume it can't be that!

[pudding]

@Gtcpaul1971 I put a new MAF in last week and this problem has been conspicuous by it's absence.  I reminded myself about it in traffic after work tonight and it's significantly keener to pull away in 1st when cold.  The rumble is there still around 1000rpm on the clutch bite, but greatly reduced.  It's a different car in traffic now, and also when crawling up a hill in traffic, and reversing up my steep drive.  A heck of a lot smoother and easier to pedal.

In fact the whole driving experience has improved for the better.  Best it's been for 3 years!  Much smoother, more eager to rev and less pedal to get the same performance as before.

This is how it's always been with sodding MAFs on VWs.  They're fickle things, even brand new ones from VW.  No rhyme or reason to it, but the latest one appears to be a good one!

[Gtcpaul1971]

Hi mate,
Thanks for the update. Think mine is actually a bit worse at the moment.
How much is it to replace the MAF?
I am thinking of selling my car and buying an 08 ish gti with lower miles as I love it and want to keep it a long time.
Just don't want to spend anymore on it after spending 1k on all the common fault stuff in a few months so far. Would rather put that money into something newer. Mind, not sure it would sell with that noise at low revs?

[pudding]

I got mine off ebay for £90 from Deutsche carparts - new old stock - but normally they are £120+VAT from the dealer.   Not the cheapest of punts unfortunately and no guarantee it will sort it on yours, although changing the car is an even more expensive proposition     Perhaps time for DSG?  Although they have their own quirks!



   

[AndyTFSI]

I to have this same noise on my edition 30 and its done it ever since I bought it. I've now covered 30K miles and the noise hasn't got any worse but it is a little annoying. I've had 2 different mechanics which I trust try the car and they have both said that its a common noise on cars with the 2.0 TFSI engine and manual gearbox, they both said not to be concerned. My clutch and DMF are due to be replaced in a few weeks so i'll be interested to see if it makes any difference to the noise. I was initially worried about it after reading the dreaded crank thrust bearing failure stories and thought it might be related.

I've noticed that the noise is louder when the outside temperature is lower, once the car has warmed up after a few miles the noise it much less obvious when pulling away.

[pudding]

Yeah I'm thinking this noise is quite common and mine too has done it for a number of years, both with the original clutch/DMF and a new Helix Clutch/new DMF.  Perhaps some people just don't notice it.

You would know if you had thrust bearing wear as the gears would be a pig to engage.  It's not that common an issue, only heard of it on really early GTIs, but people with uprated clutches need to be mindful of not pressing the clutch down whilst cranking.  Double the factory pressure plate stiffness pressing on a dry bearing - not good for lifespan.  You can easily check crank end-float by levering on the crank pulley with a pry par or big screwdriver.  If it moves in an out a good 5 or 6mm. Yup, the thrust bearing is toast.

Mine only does it when the idle speed is below 1000 and cold.   If I start her up and the 1100-1200 fast idle is engaged, I can just lift my foot off the clutch with no gas pedal and it pulls away smoothly and quietly.  1000rpm seems to be a dead spot.  I've seen the ECU doing weird things with the ignition timing that rpm....only when cold.....only when taking the bite up on the clutch......and at exactly 1000rpm.

I just need to try and figure out why it's doing that.   Could be an idle fuel mixture discrepancy (hence why a new MAF improved things a lot on mine), or it's just doing some kind of weird rpm limiter thing.   I might try disconnecting the clutch switch and see if that is a factor in this.   Not sure how else the ECU would know the clutch is biting or not.  If I hold the rpm at 1000 with the clutch up when cold, nothing, dead smooth and stable!

[Gtcpaul1971]

I have bought some MAF cleaner? Not sure how good this is?
When my car was in last time the car was over and under on its calling for fuel ? He showed me some sort of graph showing fuel mixture or somethjng (cant remember) and it was a zig zag, below and above the line. Didnt look right to me. I said the fuel consumption was crap at tge moment down to 20mpg around town with normal driving. He didnt seemed concerned.... wonder if i have MAF issues too?