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3rd Generation Honda Prelude Common Problem Fixes

Posted: Mon Mar 31, 2008 1:01 pm
by spiffyguido
Hey everyone,

I thought I would start compiling a list of common fixes for the Honda Prelude.

Bouncing (Fluctuating) Idle
It's very common to hear of a Prelude that has a bouncing idle problem. What usually happens is that once the car warms up, the idle will fluctuate in between about 750 rpm and 1500 rpm whenever the engine isn't under load. This can be very annoying.

In my experience, 90% of the time this problem is caused by a faulty Fast Idle Valve. Inside the Fast Idle Valve there is a plunger that moves up and down dependent on the engine temperature. When this plunger stops working correctly, it will often cause the engine rpm to fluctuate.

To fix this problem, start by unscrewing the cover on the Fast Idle Valve (located on the firewall side of you intake plenum, bolted near the throttle body). Look inside and use a large flat head screwdriver to verify that the plunger inside is screwed in all the way. Replace the cover.

If there is still trouble, re-bleed your engine coolant system. The Fast Idle Valve relies on the coolant temperature for proper activation. If your coolant system hasn't been bled well you may have problems.

If the idle still fluctuates, replace the Fast Idle valve. You can get a new one from Honda, or if you can, save some money by purchasing one from an auto wrecker. Additionally, it is possible to buy a Fast Idle Valve on Amazon
Note: As an amazon associate, I earn from qualifying purchases.. Be sure to check fitment with your Prelude model before purchasing though.

Re: 3rd Generation Honda Prelude Common Problem Fixes

Posted: Sat Oct 18, 2008 4:52 pm
by PEL
Man you don't know how much this post helped me. I've been going insane trying to figure out why my car was idleing wierd. I've tried different IACV's and nothing was working and every place I brought my car to they couldn't figure it out. When I was done screwing in that white plastic fast idle piece and turned on my car, hearing it idle @ 900rpm for the first time in over a month was the greatest sound i have ever heard and I really can't thank you enough. I feel like an idiot not finding this post sooner but all is well that ends well. Thank you and keep up the good work.

Re: 3rd Generation Honda Prelude Common Problem Fixes

Posted: Fri Nov 30, 2012 3:12 pm
by MikeKnight
Is there a similar valve on the TWIN CARB version?

I ask because my idle is erratic too when the car has warmed up with the idle varying between 1000 RPM and 600-ish RPM, sometimes causing it to cut out completely which is very embarrassing when you're at a busy junction.

It does it more when a lot of electrical items (stereo, heater, demister) are turned on too which is very odd but likely unrelated.

Re: 3rd Generation Honda Prelude Common Problem Fixes

Posted: Sat Dec 01, 2012 11:54 am
by spiffyguido
Yes there is a similar setup on the Carb models. These valves are basically part of the choking mechanism on the engine to help with cold warm ups.

Re: 3rd Generation Honda Prelude Common Problem Fixes

Posted: Tue Dec 01, 2015 5:09 pm
by Speener
A list of common oil leaks would be awesome. I remember seeing one for 5th gens on another forum when I owned one.

Re: 3rd Generation Honda Prelude Common Problem Fixes

Posted: Thu Dec 10, 2015 9:39 am
by spiffyguido
Speener wrote:A list of common oil leaks would be awesome. I remember seeing one for 5th gens on another forum when I owned one.
Head and Valve cover gaskets
Cam Oil Seals
Worn Piston Rings