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My “new to me” 2010 VR6 Touareg has around 77,000 miles on it. I’ve started noticing that in the mornings when it’s cold and you first start it, it will idle a little rough for 20-30 seconds. Then when it warms up, everything is fine. It runs great, has plenty of power, no real issues at all. I don’t know if the previous owner has ever changed the spark plugs……I’m assuming that could be the problem? Is there anything else that might cause this issue? Or is that pretty normal for the VR6 motors?

Thanks!
 

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I will share my opinion that this is normal for the 3.6 VR. Note that this (however) depends on how rough it is running. It has been my experience that this is normal at certain cool to cold temperatures and sounds a bit like a car with a racing cam (idles surges and is chaotic...until suddenly it is normal).

My opinion is this is due to the Homogenous Split Catalytic Heating Process (see page 39 of the attached). Fuel is injected twice: 1) During intake for proper fuel / air mixture then 2) Right before ignition TDC to increase exhaust temperature to heat the cat. This would explain why the rough idle will suddenly disappear when either 1: A certain time (like 15 to 20 seconds has passed) or at a certain RPM (like if you jump in and start driving).
 

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check your crankcase breather too. It's been known to clog up.
 

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My VR6 did this with old plugs and brand new plugs no difference, a mechanic told me that dirty valves (from direct injection, no fuel going on valves) could contribute to make this more noticable.
 

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Crankcase breather (as mentioned)

Plugs - check when they've been changed

Coils - go intermittent before dying, if you've got a vagcom you can check for a miss fire code

Also the plug holes can fill with water
 

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Just ran across a TSB for the rough idle on cold start. TSB # V011331. Apparently there is a software update for the ECM. Any thoughts? I'll attach the TSB. My Treg is running one of the old software versions #8643.
 

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I was thinking the same thing. I was hoping someone with VCDS that has this condition could confirm if they are in the "old software" group.
 
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