decoy Posted August 28, 2020 Share Posted August 28, 2020 Hey there, I have a 2010 LGT with 165k on the dial. The car runs perfectly and quite strong, but has one minor quirk that has been bugging me. When I start the car after it's been sitting over night, and the engine is cold. during the first 30-60 seconds of idling, it's a little rough. I can feel the engine having a few little "hiccups" Once she's warm, smooth as butter, but it's still something I notice and don't really like. Where should I start looking so I can fix this little issue? I recently did a full tune up, including a new EGR valve and replacing all fluids. Thanks! Link to comment Share on other sites More sharing options...
delbon Posted September 7, 2020 Share Posted September 7, 2020 Maybe the O2 sensor is going bad. Link to comment Share on other sites More sharing options...
cww516 Posted September 7, 2020 Share Posted September 7, 2020 Could be that, or possibly a vacuum leak that goes away as things warm up and expand. I know for a while, there was an issue with intake manifold gaskets doing exactly that- could be worth getting in there with a can of ether on a cold start and seeing if you can find a leak somewhere. Link to comment Share on other sites More sharing options...
5thGenCVT Posted December 19, 2020 Share Posted December 19, 2020 I know this might be late but a dirty air filter can cause that and so can a dirty MAF sensor. Did you ever get it resolved? Link to comment Share on other sites More sharing options...
creep_nu Posted December 21, 2020 Share Posted December 21, 2020 my engine had run rough at cold idle since i got it(100k miles). When I had my head gaskets done(145k miles), i had a couple worn shims and buckets replaced and valves adjusted and was absolutely floored at how smooth it idles on cold starts in the cold. could be something like that for you. Link to comment Share on other sites More sharing options...
decoy Posted December 22, 2020 Author Share Posted December 22, 2020 I know this might be late but a dirty air filter can cause that and so can a dirty MAF sensor. Did you ever get it resolved? As of now, the rough idle is so minor and only lasts for about 10 seconds before she's idling perfectly. I'm suspecting a slight vacuum leak when it's cold, and I've heard this is often caused by the tgv gaskets. If it gets worse I'll take the intake apart, otherwise it's so minimal I don't really care. my engine had run rough at cold idle since i got it(100k miles). When I had my head gaskets done(145k miles), i had a couple worn shims and buckets replaced and valves adjusted and was absolutely floored at how smooth it idles on cold starts in the cold. could be something like that for you. I hope it's not valve related, I'm sure that would be a pain in the ass to adjust given the location of said valves. Car idles and runs perfectly for the most part so I'm not too worried about it. Link to comment Share on other sites More sharing options...
creep_nu Posted December 22, 2020 Share Posted December 22, 2020 yep, hope it's not, but if you ever end up having to do head gaskets, might want to make sure you're using a reputable shop that knows what it's doing and will check and replace those things Link to comment Share on other sites More sharing options...
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