Car: 1990 Honda Civic Si ( 115k Miles )
Problem: Fluctuating Idle

What are some possible solutions ? the car runs great, just has some fluctuating idle at random times from 800-1100RPMS.

 

vacuum leak
dirty iacv

is where I would start

 

Ok thanks ! Is it pretty difficult or time consuming to fix? I wanna do it asap, but I work 9am-4pm. And I would like to do it as soon as possible!

Could it also be my fuel system? I was told that maybe a fuel injection cleaner would do me well, or "Seafoam" but im pretty skeptical on both, and i dont wanna pay someone else to do it for double the price.

 

Search how to clean the iac on here in the faqs. There should be a good how to. Or you can buy a new one. Some people tell youto clean it, others will tell you to just replace it but they run 100-140 dollars. I'd start by cleaning, personally. Try to save some money for what will go wrong next.

 

Yeah thanks ! Il have to look that up.


Another question. I just changed my heater core hose, due to leakage of coolant, and I'm pretty sure I took the appropriate procedure to refill and burp everything and the engine idle is fluctuating. My idle is now at 850-950, right below the "1" mark, you think it has something to do with the IACV as well? Or another problem?

 

I would really try cleaning IACV I cleaned mine yesterday because my idle would "hunt" between 750 and 950. I used used carb cleaner and an air compressor after to dry it out. It idles a lot better, sits comfortably at 750-800 when its warm.

 

Could also be the FITV. Try cleaning it as well.

 

Thanks guys il try all those things on my day off on Friday, appreciate it

 

What do you guys think about "Seafoam" , I've herd it can do some help

 

So you replaced the heater hose and now you have the idle issue?
Or did you have the idle issue prior to replacing the hose?

If you just got the issue AFTER the hose install, then likely you have some air in the water system.

 

I changed the hose and properly burped the coolant, it has seemed to solve the idle issue!

The only idle issue I believe is from my bad alternator, and it will be changed pretty soon here. Thank for the help guys !