I just got my car running again afte aout 2 years i did a de swap in my 89 s 13. its running kinda rough and sometimes it wants to rev up to about 4000 rpm.and once you rev it alittle the rpms are really slow to go back down. i'm sure that the rough running is a vacume problem or somethig like that. but whats up with the high rpms and the slowwreturn to idle??

 

What do you mean high RPMs? is it an auto? It could be a vacuum issue.

 

its a 5 speed. the rpms go up tp abput 4000 and stay there.

 

check your throttle cable and your TPS to and verify that both are not loose.

 

i know the throttle cable is tight

 

check you AICV also


............before all that get down there and run a ecu diagnostic. it will tell you whats going on and save you time.

 

whats aicv??

 

Air intake control valve

its the purple plug on newer manifolds brown on older ones.. make sure its plugged up.

here is a picture of the back of my manifold for reference.

 

FAIL, no picutre big.



im pretty sure my pictures wrong.

 

no your picture is right have faith little buddy lol.. my connection sucks lol

this is from my manifold

 

Oh sorry big. aha. and Big, I'll be posting something in my build thread a little later. Can you take a look and help me out? ill take alot of pictures, i just need a few intake manifold questions answered. haha.

 

so what does it idle at the rest of the time?

 

It idles at about 800-900 but rough

 

probably stupid questions...but was your car at normal operating temp or just after you started it? What are the condition of your spark plugs and wires?

 

not stupid questions at all, i was just wondering the same thing.

while the iacv may be partially to blame, i've never seen it cause an engine to idle higher than 2.5k rpms. that's not to say that it can't happen, i've just never seen it happen. i don't suspect a vacuum leak either, i'm thinking that something may be causing too much fuel to be dumped, that would explain all the symptoms.

but like always i recommended you check for trouble codes. checking for codes doesn't always provide a definite answer, but it typically does narrow the list pf possible problems.