Rough idle

[GazzaA3]

Afternoon.
Seem to have devolved a bad idle.
Also car revs up to 2500rpm and drops.
As video will show
Recently changed my alternator and battery and then this issue appeared instantly, have check all pipes around this area but all looks good.




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[GazzaA3]

Can not seem to work out how to put the video up, but along with it rev'in up to 2500rpm and dropping again every 30 seconds or so, when changeing gear the revs don't drop for a few seconds..

Any ideas what could check? Haven't got access to vcds at the moment


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[badger5]

any codes?
air leak off inlet manifold?
drive by wire or cable throttle engine?

 

[GazzaA3]

Iv double checked the lines under the inlet which all seem fine.
It's drive by wire, 2001 s3


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[badger5]

between gear changes often clutch switch the culprit

 

[GazzaA3]

between gear changes often clutch switch the culprit

Clutch switch cause it on idle aswell?


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[badger5]

hmmm. it does give the ecu a load signal so never say never.
you can see clutch activation around block 060 from memory..

 

[Alex C]

http://www.ross-tech.com/vag-com/m_blocks/

 

[GazzaA3]

Had a bit of time on the car today, had a code of P0130.
Took lamaba sensor out, cleaned it up and code hasn't come back.
Cleaned senor up in the picture as was covered in oil inside.

Now it idles like a pig still but revs don't rid e and fall like before.
Any other sensors I could look at and clean up?

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[GazzaA3]

Went for a little drive and this happens...

Idles like a bag of nails, drives not to bad..
Clear them codes, ran the car and still get this..

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[GazzaA3]

On idle, slight poping comeing out of the throttle body.
Can hear it by ear with the boost pipe on.

Can knocks sensors cause this? My connectors don't look to great


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[badger5]

if lambda is'nt working properly your popping is likely lean spit back...
first thing to fix would be this
see lambda values in 001 and 031 engine data blocks in vcds

 

[GazzaA3]

I changed lambda last night, still got this issue though..



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