# Slightly lumpy idle



## terryjacobs (Feb 28, 2008)

Hi all,

Perhaps i'm being pedantic but wanted to confirm this.

I have a 2001(X) 225. The idle seems very slightly rough. I would say it idles with a variation of about 100-200rpm either side of the idle which if I recall correctly is about 900rpm.

It's a very slightly lumpy idle and by no means jumping around. Is this normal on this sort of age TT?


----------



## anty1985 (Oct 5, 2007)

god knows mate but mine does the same. Taking mine to awesome for a full service and the cambelt work. hopefully that will sort it! not sure if its normal or not thou.


----------



## Stub (Mar 17, 2005)

sounds like you have boost pipe split, get someone to rev the engine a bit while you move the pipes around to hear if there is a split, I have had three split pipes now, one caused exactly the same symptoms as you describe, and lost power.


----------



## terryjacobs (Feb 28, 2008)

Thanks for hte replies.

I had the cambelt and service done on Fri so I wouldn't expect that to cure it to be honest with you.

I'll correct my original post. The idle is abotu 1100 rpm and the needle moves perhaps 1-2mm up and down on idle. It is very minor.

I will check the pipes thanks. I think it's probably fairly normal due to the age and perhaps a sensor is dirty or on the way out that controls the idle speed.


----------



## TTmarlin (Mar 18, 2008)

terryjacobs said:


> Thanks for hte replies.
> 
> I had the cambelt and service done on Fri so I wouldn't expect that to cure it to be honest with you.
> 
> ...


Your idle speed it Too high, could be air leak, or have you cleaned the throttle body?? or done a TBA with VAGCOM??


----------



## terryjacobs (Feb 28, 2008)

Hrm, i've only had the car about a month. What should the idle speed be?

What's a TBA on VAGCOM? I've got the limited free version of VAGCOM not sure if I can do one with that.

THanks


----------



## TTmarlin (Mar 18, 2008)

terryjacobs said:


> Hrm, i've only had the car about a month. What should the idle speed be?
> 
> What's a TBA on VAGCOM? I've got the limited free version of VAGCOM not sure if I can do one with that.
> 
> THanks


idle speed should be around 850 - 950 rpm.

Vagcom is a windows based PC program, which amongst other things allows you to carry out diagnostic work and make adjustments to the various ECU's on the TT.

TBA, is throttle body Alignment, which is or should be carried out after youve clean the throttle body out


----------



## terryjacobs (Feb 28, 2008)

Hi thanks for the replies.

The car had a service and cambelt last week. I'm sure the idle was about 800-900 then and now it seems to be nearer 1100. Is it possible to be a result of something done when the cambelt is changed?

I have the 3.11 free version of Vagcom. Can you do a TBA with that?


----------



## Whitter45 (Sep 21, 2005)

TBH my car always had a slight rough idle

But as said around 850 it should be

Earthing the engine seems to help


----------



## terryjacobs (Feb 28, 2008)

Thanks all. I removed fuse 10 (ECU) for a couple of minutes and now everything seems to have corrected itself and i'm running back at about 800 rpm or so.


----------



## terryjacobs (Feb 28, 2008)

Right all, sorry to bring this one back up.

I've checked the car and the idle speed starts at about 1100 and quickly lowers down to 850 or so when it's warmed up.

So idle speed doesn't appear to be an issue. However the needle is still jumping a little and when listening to the exhaust it sounds possibly like misfiring (although to be honest i wouldnt know what that sounds like).

Are the likely options
MAF and TBA? If so i'll work on them cleaning/testnig them.

I think i'll be taknig it back to the garage as they did a service and cambelt last week and this problem seems to have started since then. Could it be a timing problem when they've put theengine back together?


----------



## TTmarlin (Mar 18, 2008)

terryjacobs said:


> Right all, sorry to bring this one back up.
> 
> I've checked the car and the idle speed starts at about 1100 and quickly lowers down to 850 or so when it's warmed up.
> 
> ...


Most likey a coil pack on the way out


----------



## JAAYDE (Aug 15, 2006)

If the timing was out trust me you would know about it ! What kind of mileage do you have ? I cleaned my injector tips and changed the injector top seals and that helped my lumpy idle.. From my experience with 4 cylinder engines is that the idle is far from say a 6 cylinder.. Also as Stub has said try listening for air leaks under the bonnet that a good start !


----------



## JAAYDE (Aug 15, 2006)

If the timing was out trust me you would know about it ! What kind of mileage do you have ? I cleaned my injector tips and changed the injector top seals and that helped my lumpy idle.. From my experience with 4 cylinder engines is that the idle is far from say a 6 cylinder.. Also as Stub has said try listening for air leaks under the bonnet that a good start !


----------



## TTmarlin (Mar 18, 2008)

So your saying a coil pack 'tracking' wouldnt cause a lumpy idle??????


----------



## Juber (May 20, 2007)

Im convinvced its the MAF sensor.

Unplug this off your air filter and run the car with out the MAF and see if it continues to bounce on revs, If it doesnt then obviously its your MAF sensor and not something like windscreen wipers :lol:

mine does that, but it doesnt really bother me.


----------



## John-H (Jul 13, 2005)

Could be in need of a throttle body clean in line with the Audi advisory for this very problem.


----------



## terryjacobs (Feb 28, 2008)

Thanks all, when i'm off tomorrow i'll try disconnecting the MAF and as a secondary if not i'll try cleaning out the throttle body.

Very helpful forum here cheers


----------



## terryjacobs (Feb 28, 2008)

Right,

Have taken the MAF sensor and it appears clean although didn't have any isoproply (spelling?) to clean it with to be fair.

Also blown some cleaner through the T/B. Initially VAGCOM was logging 750-800 variation in RPM. AFter the clean it appeared to be a constant 800 rpm. Will see how it is when it's cooled down again.

Finally, my coolant temp at warm was 67 deg C. Is this a fairly normaly value?

Does anyone know what the HO2S Control value on VAGCOM logging refers to? mine goes from avg 3 to -4 then back again. I have no idea what that should be.

Cheers,


----------



## TTOWNER. (Mar 3, 2011)

Mine sits very low and bounces between 660-720rpm when stationary... i have new plugs, coils and injectors... Could be MAF or, vacuum?


----------



## Spacemonkey (Mar 5, 2021)

Mine wobbled around the 800 mark, but getting rid of most of the breather hoses fixed that. Now the Crank Position Sensor is playing up. FFs....


----------

