Bouncey idle, loud intake, hood won't pop. :( - Honda Prelude Forum

mr. r00t · 11-01-2005, 01:30 PM

Hey guys,
Last night when I got off work and began to drive home I noticed while stopping at red lights my idle was bouncing from 800rpms-3000rpms. Usually, the last 2 years this has happened, it would only bounce from like 800-1500 and only when it was really cold. Last night, it was bouncing more violently from 800 to 3k to 800 to 3k to 800 to 3k constantly, wouldn't stop. So I parked it cuz I was exhausted from work. This morning I go out, start it up, same thing. The idle is going from 800-3000 and back and forth still. So I pop the hood and go out to take a look if anything is going to jump out at me. The first thing I noticed before I got to the hood was the intake was much louder than usual. Typically its a quiet sucking noise, today it was ultra loud sucking noise. Then, I realized the hood hadn't popped. I tried again, it won't pop. I pulled it like a dozen times (without being rough with it) as normal, and it won't pop. I find it hard to believe all 3 of these things sporatically happened all together at the same time and are unrelated. Does anyone have any ideas while I wait for payday before I run the car to my shop as to what might be going on? Time to wash off the Integra.

Oh, it's a 93 Si with ~170k on it.

Thanks,
jg

95_5speed · 11-01-2005, 02:00 PM

Another car i had would idle really nuts like that when the throttle body was not sealed / connected properly .. uhh and the hood latch breaking? If it's a cable, it may have just finally been its time and decided to bust on you now so you could consolidate your trips to the shop?

mr. r00t · 11-04-2005, 08:56 AM

Thanks for the input. I guess I'll see what my shop says.

95_5speed · 12-28-2005, 10:32 AM

Ever get an update on the issue, my stupid car just started bouncing from 800-2500 last night, In the extreme cold like yours.

Man this car is a piece. lemme know. ~ Brett

d3adp · 12-28-2005, 11:55 AM

TPS sensor?

Sonik_Fury · 12-29-2005, 05:12 AM

The IACV is on the intake manifold, #17. It has a coolant hose, so freezing damage seems possible. Take it off & take a look?? Clean the screen on it, spray it with brake cleaner...just be careful taking the screen out to not tear it. Cleaning is only a temporary fix, sometimes it fixes the idle, sometimes it doesn't. If it doesn't then you need to replace it.

There's also coolant running thru the intake manifold. So maybe it damaged the IM gasket against the head?? (Just guessing) Vacuum leaks can probably do what you describe too...

95_5speed · 12-29-2005, 06:50 AM

Thanks sonik

I happen to have 2 complete intake manifolds sitting around, so I know i have the parts to replace / fix. My concern now is, My coolant / water mix is about 70/30. I tested my coolant, and it wont freeze just about ever. It would have to be about 70-100 below zero to freeze my coolant, do you still think its possible that I need to clean / replace the IACV? and damn it! I hope my Manifold gasket is still good, I just replaced it a couple thousand miles ago when I had the head rebuilt.

Well, I guess I have a weekend project to do for new years.

Thank you for the advice so far guys!

jsmooney · 12-29-2005, 09:19 AM

my F22B idles like crap in the winter

as well

95_5speed · 12-29-2005, 10:11 AM

See, this troubles me. You guys have driven your car, and at idle it acts funny. Once my car has warmed up, its terrific. This strange revving problem only occured to me on 3 of the previous 50 cold starts and once i shut the vehicle off, then turn it on again the problem is gone.

I wonder how this same situation, can occur at different times, warm and cold?

xbi0s · 12-29-2005, 10:39 AM

My old accord would do this. Check your vacuum lines running into the intake manifold for cracks or leaks. I had a line dry rot out on me which was what would regulate where my idle would be @ cold. When the motor warmed up the problem went away. usually it owuld only start the crazy rev's if I touched the gas a bit.

95_5speed · 12-29-2005, 10:48 AM

For the ppl who have the problem, and want pics:

Just a little more detailed then the exploded view

Now I'll go mess with my own instead of my spare, I hope this works.

95_5speed · 12-29-2005, 11:11 AM

K, I cleaned it properly, and gently, made sure the electrical was connected properly and coolant flow is fine through there no damage. Started the car, and now the bounce in the idle is even worse, and it happens all the time.

Any other suggestions?

RedBB2 · 12-29-2005, 12:28 PM

check the fast idle thermo valve under the throttle body unbolt and take it off make sure the little valve in there is screwed all the way down its #13 in the picture there is a little valve in there that i cant remember if it should be all the open or shut. This happened to me with the very loud intake and bouncy idle and this fixed it.