I just recently bought a 95 del sol with a b1b1 swap in it....when i start the car when the engine is cold the rpm's bob up and down but only when its cold....what could it be...

 

so it idles funny when you first start it up? maybe the idle sensor? i had the same problem with my d16z6 a couple winters ago. it hasnt done it sense though. i went though last winter and it didnt do it so maybe it'll just go away.

 

IACV, FICV, Def. a vacuum problem. check hoses around TB and back of intake mani for cracks/damage/missing.

 

sounds like IACV, honda's tend to have that issue

 

Can of intake cleaner can be your best friend.

 

check your IACV and also make sure you have no vacuum leaks. Also make sure you dont have air in your cooling system and double check your TPS and make sure it is getting the right voltage at close and open throttle. I had the same problem with my ride, (92 hatch w/ b16a2) my problem turned out to be the TPS and I also had some air in my cooling system. Works like a charm now. Good Luck

 

thanks for the help i'm pretty sure its the iacv