My car is boosted, haven't had any problems yet. Here in WI, it's now the time of the year where it could be 80 one day and 30 the next. The first time the temp got down to about 40 and i tried starting my car, it had a rough idle for about 5 seconds, then all of the sudden it's like you could feel something kick in and it starts idling normally. It did this on cold start-ups for like a week, and now it does it everytime (even when it's warm outside). By rough idle I mean the car will idle at about 500 rpm and have a deep rumble/vibrate harder than usual. Sometimes it helps if I tap on the gas and it fixes the problem immediately, other times I'll tap on the gas and it will still take the few seconds to kick back to normal.

I have one-step colder NGK spark plugs, dsm injectors w/resistor pack, walbro fuel pump. These are the only things I've changed that I think would maybe have something to do with it.

 

what kind of management are you using?

 

hondata s300

also, have skunk 2 intake manifold and blox throttle body.

 

I know that some management systems make a car jump up and down at idle for like 10 to 15 seconds. Dont know about hondata.

 

Yea, like I said though, it didnt do it for the first 2 months I had everything done.. just recently started.

 

Any CEL?

Might just be a dirty IACV. Try cleaning as detailed in Greddy_Civic's DIY thread.

Other possibilities include a faulty coolant temperature sensor or a little air trapped in the cooling system.

 

no CEL, I'll have the guy who installed it check it out.

 

it is probly the oil you are using if it is cold thier most of the time you need to use like 5w30