my girlfriend has a late 95,96 GLI civic. about a year ago she got a new computer installed and it had a harsh idol we were told it would disappear after a week or 2 any way a year down the track and it still does it (it revs its self between 1 and 2000rpm when in neutral) its really annoying and i don't think it is any good for the car can anyone help

 

Fast idle thermal valve or idle air control valve most likely. Also, if the coolant is low or the cooling system has air in it it will cause that problem too.

 

thanks heaps hay ill bleed the coolant and check that today but what is the fast idle thermal valve and idle air control valve and what do you rekon will be wrong with it

 

Look at my thread a few posts down...

 

The fast idle thermal valve (FITV) is the valve that is used to control the idle during warm up. It's what makes the car idle fast when the engine is cold. The idle air control valve (IACV) is used to control idle conditions such as turning on A/C, headlights, etc. It's what kicks the idle speed up and down depending on what loads are on. On the 96-00 Civics the FITV and IACV were integrated into one pieces whereas the 92-95 (and older?) Civics used two separate control devices. Generally what happens is over time those two things will build up carbon over the screens and inside the devices which restricts the amount of air that flows through them and causes them to work improperly due to being plugged up. Most of the time just cleaning them out with a small brush and some de-carbon spray works wonders, but sometimes you just get stuck with a broken piece. There's numerous write-ups on the internet to cleaning those two things, just gotta google it or search on Honda-Tech.com.

 

I think the installation of the computer causes that...

 

Are we talking about Simon Cowell?

lol, jk.
It is most likely the FITV. However, it seems strange... Did this occur exactly after the new computer was installed?