Why is my 98 honda prelude engine idling rough?

SOURCE: 1989 honda prelude enigne idles high then low irratic

I had the same problem on a Rover. There was a leak in inlet manifold that was caussing the problem.
To verify, spray some sealant to temporarily seal the inlet manifold .and the eratic idling should disappear for some time.
If it does, you know there is leak in inlet manifold which you can take of and refit with a new gasket.

SOURCE: honda prelude si 1991

I had the sme problem with my 1992 prelude si. The problem with mine was that the intake manifold gasket was leaking horribly. The idle would go up and down just setting there, but when I held the brake long enough it stopped. An easy way to see if it is the gasket is get WD40 or Brakleen or soemthing like that, and spary it where the intake manifols bolts to the block. If you hear a change in the idle speed (faster or slower) just change out the gasket.

Ned C Cook

• 3433 Answers
• Posted on May 22, 2009

SOURCE: running rough, wont idle, bad gas smell

Possible injector failure. locate by disconnecting injectors one at a time. The one that makes no change is the questionable. Status of spark plugs need chkg also. pull the plugs an the one that looks washed is questionable good luck

SOURCE: rough idle when warm and in gear, idle pulses slightly every now and then, check engine light is on

It sounds like the timing belt is off a tooth. Did you have it scanned to see what code was in the computer? These engines will surge when the cam timing is off.

SOURCE: 1983 honda acc cold start wont stay running when cold idles rough

try checkin your idle air control. most of the time it is a vacuumn line going into intake.pull it off and if the car revs up dont worry, it wont hurt it. if it does simply put it back on, if it dies you have a bad vacumn.