Emission Control warning Light, erratic idle speed = my car doesn't like motorways!

mancdan

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I keep getting a problem whenever my car has been on a Motorway/dual carriageway run.

I recently went from Manchester to Glasgow for the weekend and upon returning back to Manchester the Emission Control Warning light came on when I exited the Motorway after approx 4 hours driving.
The light stayed on for 2 days and then went off. This was 2 weeks ago.

The light has now come back on and been on for approx 48 hours and I haven't done any long driving runs.

The other problem I have is erratic idle speed again every time I go on a motorway run, even if its just for a couple of miles.
When I exit the motorway and come to a stop, the idle speed varies between 1000 and as much as 1400 rpm sometimes, it sounds like my car is revving its tits off!
The only way I can bring it down is to gently let the clutch out a bit, but as soon as I depress the clutch again the idle speed begins to creep up. Its so annoying that I now hate it every time I use a Motorway or similar type of road.

I have had the Coil pack recall done plus recent Cambelt & water pump change, but the erratic idle speed was present before these were done anyway.
Anyone have any ideas what the problems could be? Could they be linked?

Thanks, Dan.
 
Emission Control Light now gone off again!

Could the ECU be temperamental/faulty and does anyone know approx cost to replace the ECU?
 
Could be the PCV valve, a scan would confirm this..more info here

Thanks Solaris, this sounds just like my problem as I have noticed MPG has gone worse too.
Can you remember the price of the PCV Valve and is that the Audi Part Number (part number 06F129101N)?

Cheers, Dan.
 
mine does the same ocasionally, just fitted BSH PCV fix plate but still does it. seems to be an issue with a split pipe to my carbon cannister.

As Solaris says though PCV is first port of call
 
i bought a plate that gets rid of the PCV part completely, turns out my PCV was fine anyway (recently replaced) by precvious owner.

sorry can't say how much a new PCV is
 
OK, PCV and gasket successfully changed last Friday. Took me about 15 mins once I got the correct tools!
Part Numbers & prices were as follows: PCV at £37 = 06F 129 101N and Gasket at £18.40 = 06F 103 483E

BUT, still got the erratic idle issues and the Emission Control Warning light has come on again :wtf:

Is it time to get someone with VCDS to plug it in??
 
i cant belive ppl still change parts when hey havent had a scan for codes
its a waste of time and money
it could be a split pipe or even the MAF
unplug the maf see how it runs.
 
i cant belive ppl still change parts when hey havent had a scan for codes
its a waste of time and money
it could be a split pipe or even the MAF
unplug the maf see how it runs.

I did think that bez but read somewhere that changing the PCV valve after 50k miles was a good idea anyway, but lesson learned!
Where abouts is the MAF?
(By the way, was it you I came to in Sheffield to clear my airbag light when I changed the wiring under the seat?)
 
I did think that bez but read somewhere that changing the PCV valve after 50k miles was a good idea anyway, but lesson learned!
Where abouts is the MAF?
(By the way, was it you I came to in Sheffield to clear my airbag light when I changed the wiring under the seat?)
iv done a few infact loads
so yeah could have been
across from the pub an carwash ?
 
I think so, on the main road with tram lines?
Rough idea as to where the MAF is so I can unplug??
 
yeah thats me
the maf is on the left as your looking under the bonnet on the pipe going to the airbox
put a pic up ill point it out.
 
Here you go Bez, hope picture is close enough.

A4 Engine bay
 
remove the big airpipe
and you will se eit under there
 
Should the MAF just unclip and pull out or do I need to remove those security torx screws?
 
Unplugged what I thought was the MAF (part no. 06F 906 461A) and ESP light has come on!
Have I unplugged wrong part?
 
the MAF may send a light on
there is 2 security screws holding it to the tube
when u get a new maf its already in that tube
to clean it u need to remove them i have a use 1 with around 1k miles on it
take a pic with thebig air pipe off ill point it out
 
I didn't need to remove air pipe to unplug the MAF so will need to remove it and then take a pic for you.
Let me know how much you want for your used one too.
Cheers.
 
(it was the MAF you unplugged)
how did it drive when you unplugged it
 
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Haven't drove it yet but am about to leave work so will know in the next few mins and report back later!
 
Well, unplugging MAF didn't alter the erratic idle as it appeared again this morning whilst in traffic and I had only driven on A/B roads, max speed 35mph and done approx 6 miles. Also the Emission Control warning light came on again.
I have now plugged the MAF back in again and ESP light has gone out but ECW light has stayed on.

This is a video of the erratic idle whilst at some traffic lights this morning. You can see that I revved it a little at 8 seconds to see if it would go back to normal and it didn't.
I also let the clutch out a bit at 22 & 46 seconds to get the idle down, but as soon as I depress the clutch back in, the idle speed goes back up again.

Its driving me fckin mad now and I'm thinking it really needs to go on VCDS.

[video]http://s6.beta.photobucket.com/user/dti2k/media/ErraticIdle.mp4.html[/video]
 
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if your around my way again ill scan it you
see if the problem is stored
 
Cheers Bez, I'm never usually around Sheffield but would make a special trip there just to get it scanned as its really bugging me!
When is a good time/day for you?
 
sunday after 5pm
or day next week after 7pm
 
This issue has now been fixed by Rick & Spencer at Unicorn Motor Developments in Stockport.

It turned out to be the N80 Valve and so far the idle speed is perfect and car runs a lot better too.
Cost of new part approx £25 plus an hours labour to fit.

I would like to give a big shout out to both these guys as they are very thorough and have a great wealth of knowledge.
I would have no hesitation in recommending their services.

Now to save some pennies for one of Rick's customer remaps!
 
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