btbaus

iTrader: (3)

hello everyone.

i have a 1990 NA Rx7. when ever it starts up cold, it hits 3000rpm for about 16 seconds. then it goes down to 1500rpm and it doesnt move from there until ive driven the car for about 5-10 minutes. ive read somewhere that it should hit 3000rpm for about 30 seconds then go down to 1500rpm for about 15 seconds and then settle at 750rpm. is this correct?

what do i need to do so the my car doesnt stay at 1500rpm for so long?

also, when its fully warmed up, sometimes it will idle at 2000rpm. it will go away after a couple minutes of driving. does anybody know why it does this?

im also experiencing a surging idle. it doesnt always do it and usually only within the first 15 minutes of starting the car.

somebody please help me! ive searched and couldent find anything so any help will be appreciated.

RyosukeD

iTrader: (2)

I believe it's more like 3k for around 15 seconds then 1.5k until warm. My car hangs out around 1.5k idle until warm. Now I do have some vacuum leaks, and probably a decent chance you do too. Leaks can also instigate an idle surge, so it's a good place to start looking.

Chuck

iTrader: (2)

1500 for 5-10 minutes is not that far off, but you probably have the idle speed set too high if your're experiencing surge. First, make sure you've got the TPS adjusted correctly and then set your idle speed to the 700-800 range. If everything's set right, it shouldn't surge, even at higher warm up idle speeds.

Druken

I have/had the same problem. I'm actually going to work on the car now and fix it. I got some starter fluid and started spraying the cracks inbetween the manifolds and around the vacuum lines. I noticed that when I spray the fluid around the lower manifold, I was able to get a smoother idle and sometimes it would surge a bit. So in conclusion, that is where my leak is which I believe after I fix it should bring my idle down below 1k. I think you should give it a shot, $4 from your local auto parts store and it will save you days of headaches.

btbaus

iTrader: (3)

nice thanks for all your help. ill start off with checking the tps and the checking for any leaks. Druken, let me know how it turns out.

Druken

I feel like you have a vacuum leak and its getting air in, causing the ecu to adjust the amount of fuel sprayed in each housing. So again, try the starter fluid trick and try and find your leak. Its only $4, so you aren't loosing much.

Well, my situation may be different than yours but here goes.
I have a rebuilt block with less than 10 miles on it, so it is normal for mine to idle around 1k-1.5k since the seals haven't fully broken in yet. But they say that once I add a couple hundred miles, the idle will drop and the ride will be a lot smoother as more miles are driven. But after finding the small vacuum leak, which caused the tach to jump a bit after I give it gas and let go (the surge), I resealed the lower and upper intake manifold and now the idle is more solid.