Idle Drop - Honda Prelude Forum

rasengan_kyo · 05-19-2010, 05:56 PM

So I got a 93' h22a vtec and for some reason when im driving and coming to a stop I push in the clutch and the RPM's drop all the way down to the point that it almost stalls and then will come up to maybe 300 or 400. Whats more interesting is that some days it does it, other day its fine. Sounds like maybe a fuel issue but im not sure so once again i come the Lude guru's.

f22man87 · 05-19-2010, 09:28 PM

First thing I would check is the tps possibly...does it idle at its normal spot around 950ish those times when the idle doesn't drop? Does it surge when the idle comes back up?

cena2020 · 05-20-2010, 12:18 AM

Idle Drop how to:
first you need access to the air/fuel mixture screws, usually covered by a cap on the bottom of the carbs.
second, once you have gained access you must have bike at operating temperature
once you have achieved these two things then we shall start.
1-adjust number one carb in/turn right counting turns until you start getting a rough idle, at this point you might want to use the throttle, DON'T, use your idle adjuster if needed to keep idle
2-adjust number one carb back, count the turns made at this point, to a smooth idle, rpm's might raise at this time. don't adjust the idle because of the next step
3-adjust idle the other direction/left til the idle gets rough, counting the turns again.
4-take the first amount of turns and the second amount and add, then divid by two example:
2 1/2 turns in + 3 turns out = 5.5

5.5/2=2.75

2.75 turns is where you need to set it for best idle and air/fuel mixture. you can reset your idle speed at this time. You will never enjoy your work and riding as much as you will now

there you all go! enjoy!
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rasengan_kyo · 05-20-2010, 04:30 PM

Yea when its regular it up around 900...When it drops, it slowly comes back up(2-3 sec.) I heard it may be the AICV and may just need cleaned so im gonna try that, if that doesnt work i'll replace the TPS.

red92si · 05-20-2010, 05:45 PM

Cena2020: We don't have carbs.

f22man87 · 05-20-2010, 11:38 PM

Yea cleaning the IACV is definitely easier to do than the tps. It is possible that it is that as well, though you should be getting a loping idle unless it is just starting to get clogged up. Keep us posted

Matta1 · 05-21-2010, 12:05 AM

Or you should clean the FITV (Fast Idle Temperature Valve). It's located under the throttle body, and gets dirty over time. Also the the "wax" plug gets unscrewed and should be tightened.
If something is wrong with the IACV, it will sometimes give a CEL. So unless you have a CEL, you should also check your FITV.

Rasmusm · 05-23-2010, 02:31 PM

I have the exact same problem with mine.. I tried to clean up the IACV, EGR valve, PCV valve. Nothing helped me..

I think my low idle problem started back when I re soldered my mail relay to fix the starting issues i had.. It worked perfect, im gonna re solder my relay tomorrow again and check everything. Hope it will solve it..
Else im gonna check that FITV..

ninjalo161 · 06-01-2010, 10:34 PM

hay all im new to this forum and im havinf idle problems with my 89 prelude when i pu the cluch down or come to a stop it drops to low like its going to stall i was wondering if there are derections for cleaning the ivac with pics if possible on here

92ludevtec420 · 06-03-2010, 03:02 PM

hey guys im new to the forum and i am also having trouble with my idle dropping when i come to a stop. as of right now it only happens after i have been driving for a while. i was told it could be the idle air control valve. whatever it is its annoying. i am also having dash problems so anyone who is selling the information cluster for a 92 prelude give me a shout.