Rough idle at cold start?

[toolfan94]

My friend just recently replaced my aos on my 01 boxster,no more chimney
smoking on start up since then :dance: However i did notice, that sometimes when i start it from cold start, the engine will shake or do a rough idle and then it will go away after i drive it, any ideas what might be the problem?

By the way it has about 50,500 miles and my check engine is on because of a vacuum leak.

[jcb986]

I would recommend changing AOS...it usually is the problem and this part seems to be an issue and fails eventually. As the AOS fails you get oil being sucked into the intake...after sitting overnite you get the blue smoke burn and maybe a rough idle at first then it goes away after you have burned out the oil.

[sasha055]

He said he just changed the AOS,

I had a similar problem, sometimes (more often when cold) the car would almost choke.. then it was coming back
For me rough iddle was fixed by cleaning MAF/Throttle body and replacing spark plugs/fuel filter, not sure which one did it..

Another option is that while replacing AOS you/your friend didn't connect all the tubes tightly.. a vacuum leak can rough up your idle as well.

Thanks
Sasha

[Beelzy]

I think you need to nail down that vacuum leak first, then check the MAF sensor if the shaking persists.

[Mark_T]

+1 on fixing the vacuum leak first. You really can't do any meaningful troubleshooting while that condition persists.

[toolfan94]

Thanks for the advice guys. I'll ask my friend to check if the tubing is tight on the aos,
and far as the vacuum leak, my best bet would be to go to the stealership and get
the problem fixed($642.08 with parts and labor)
I saw a diy guide on cleaning my maf sensor so I'll probably do that.

[dirkdiggler]

My Boxster idled like crap and had Missfire codes untill I changed the spark-plugs. Mine had 60k miles on original spark-plugs.
That smoothed my idle out perfectly believe it or not.