Ok, When I start my car the idle jumps up and down between 1k-2k rpm. I thought it was my IACV so I cleaned it.Well it didnt do a thing. It would only jump up and down when it would be in P or N , well today when I put it in R it started to do that and the car would act as if its going to stall out. I have no damn Idea what could it be, and I checked for any leaks in the vacum lines but there is none. someone please help me ! ! Thanks in advance


EDIT its a h23 prelude

 

I have the same problem wit mine can't figure it out drives me crazy.

Have u checked all ur grounds?

 

if its a honda, i would check all you vacuum hoses THOUROGHLY! i had that problem... IACV FITV all that didnt work... then i looked and found my vacuum pump dislodged from its mount and a hose removed. fixed it and fixed the problem. then i had it again and found a hose with a tiny crack... fixed it and fixed the problem.

 

If it is doing it, even if the car is in gear, check your spark plugs. One could be fouled. Check the spark plug cables also to see if there are any burnt insulation.....

 

is the vacum pump the big black thing on the back of the intake manifold? I have a spare intake manifold i might just swap them out. hopefully it would help.

 

Why not do the easy things first. Try out what I recommended to you. It'll only take a few minutes vice a couple of hours on replacing an intake manifold.

 

seen a bad tps cause this problem a few times...most likely its a vacuum issue though

 

http://www.emotors.ca/Articles/97.aspx

 

i would do what this guy says first... he's the one that led me down the vacuum hose road and basically brought my car back from what i thought was impending doom! lol... pretty much knows EVERYTHING about honda motors.... good luck

 

I just had this problem with my civic.. idles didnt jump.. but i was idling REALLLLY low and it felt like it was going to stall..

turns out an O2 sensor had shorted out and I had a crack around the O2 sensor in my exhaust manifold..

fixed those right up.. cost me around 800.00 and I was on my merry way.