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Discussion Starter #1
okay, some days it idles great. some days....not so great. What happens is that the idle fluctuates. When I press in the clutch it drops down, seems to stall for a second and then idles back up like normal. sometimes it just drops. I talked with my friend (a honda mechanic) and he says that it sounds like a fuel problem. I told him i have replaced the IACV and cleaned/adjusted the thingy under the throttle body. I have a new fuel filter at home but can't get the bolts undone to replace it. ill try that next. any suggestions or ideas?
 

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Updated... here is some basic info:

Poor idle can be caused by a number of things. You should always check foro the cause in this order (order of probable cause):

- Old, worn plugs (replace)
- Old, worn distributor cap/rotor (replace)
- Old, cracked wires (replace)
- Valve adjustment (too tight will lower idle)
- Vacuum leak (check hoses and IM/TB gaskets)
- Air in coolant causing thermal valve to oscillate (properly fill & bleed coolant)
- Funky EGR valve (clean or replace)
- funky EGR port in manifold (clean)
- IACV dirty (clean)
- TB dirty (clean) --> remove MAP sensor first!!!!
- Dirty injectors (should send them to someone like RC to be rebuilt)
- Defective fuel pressure regulator (check for proper fuel pressure)
- Primary 02 Sensor (if fouled it can lower idle speed)
- Bent valves (do a compression test, then leakdown if bad, repair head if valves leak)
- Bad MAP sensor (try giving it a thwack w/a screwdriver handle)

If you have messed with any of these recently, start there first.

The idle adjust screw is the LAST thing you should look at or adjust! The idle speed is controlled by the ECU and set properly at the factory. There are no bolt-on mods that will affect idle speed. Only a valve adjustment, new TB, IM, blower, turbo, or internals should have an effect like this. Fix the root cause and you won't have to dick with the idle adjust screw.

Some more "case study" reading:

http://www.preludeonline.com/showthread.php?t=208477

older threads:
moderate problems: http://www.preludeonline.com/showthread.php?t=171114
bigger problems: http://www.preludeonline.com/showthread.php?t=197498

You should be able to search any of the items listed above and get plenty of information on how to fix/address these issues.
 

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Discussion Starter #3
thanks! sorry!!! i won't post again - this problem doesnt bother me that much, i just saw the H22 idle problem and it made me think. can someone sticky the idle problem threads?
 

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Most of the time, idle is bad because the user has done something to the car. I have never seen a case where the idle just goes bad over time.

One more major cause is air in the coolant. The coolant system has to be bled out properly. If not, air pockets cause very strange idle things to happen.

The other thing I dont' see on your list is checking the plug order. Make sure the spark wires are plugged into the dizzy and the head in the right sequence.
 

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What about the older Honda engines? I'm having a problem with my OBD0 B16 in my CRX. The car would idle fine, then for a week it would idle sporatically and trip the engine light. Then a week later it'd be fine again. Now, it seems like the problem has finally become a problem. And the IM looks different than the one in my Prelude. There are a few extra valves and vacuum lines. Looks like the control valve is external and bolted on the firewall. If there isn't a difference I'll just follow the road posted above...but I wanted to see if anyone had some experience with the older Honda stuff.

...also, what about the fuel pressure regulator? Can that fail and cause the fluctuations?
 

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Discussion Starter #9
edit: i added some fuel injector cleaner and the car seems to be doing a little bit better so far
 

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Update on my situation...

I just made a gasket for between the TB and IM out of a Davis sunflower seed box, and blocked the Fast Idle port. It idles fine now. I'm planning on looping the coolant line tomorrow.
 

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i didnt remove my map sensor when i cleaned my throttle body....wat affect would this have? cause after i cleaned my idle is bouncing, any help would be appreciated.
 

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meh. my lude does the same thing, as dumb as it sounds, im sure its the octane differnce in fuel. the 7-11 87 octane = bad idle where as chevron 92 premium plus with techron it will purr all day!
 

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I have issues.My idle speed keeps on drooping when I stop, sounds like its going to stall, then recovers but ONLY WHEN THE HEADLIGHTS ARE ON.
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hey man my car is a 97 h22a4 and im having some issues with idle
when the car is cold and i start it up it idles so low it almost stalls, ive had this problem for a while but it made it worse when i installed a Skunk2 throttle body to replace the TPS sensor which i thought was the problem.

i took the car in to ProAuto and got it checked out, turns out to be the Purge Solenoid / Evap Canister. aswell as Idle air control solenoid, but the idle air is caused by the install of the new throttle body.

So the purge valve runs on a vacuum hose and feeds air into your engine with gas vapors when idling. the canister on it holds the gas vapors and if somthing is wrong with the hose or the canister itself your gunna probably have to replace it.

I just read up something else on another page which im going to try.

Quote
"For a while now I was having random low idle problems and sometimes the car would die and stall right after start up (when warmed up).
I tried everything and as a last hope, I removed the Evap purge solenoid and plugged the vacuum source on the intake manifold and instantly the car idles
better and does not stall anymore! As crazy as this may sound, my exhaust even sounds "deeper" now - wierd...
"

he ended up plugging the gas line that ran to the purge solenoid.
so its worth a shot.

Hopefully this helps you out!
goodluck
 

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Discussion Starter #17
that evap canister is just for emissions crap (I believe). if it works to run a line around it instead of running through it - do that as long as it doesnt throw a CEL. take out the IACV and clean it and put it back together
 

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I know many owners have idle issues. I have tried everything!
Took apart the idle control valve and cleaned it "wasn't carboned up"
Replaced the throttle body sensor
Checked all vacuum hoses

It started out going up and down than I unplugged the icv and it stopped the up and down crap but now it threw the check engine light and it just idles about 2300 always
Replaced the Throttle body sensor....did completely nothing????
Any ideas?
 

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suppp guys!! im kinda new to this... but anyway havin the same problems too and so far what i did is just clean the aicv, but still having the same problems.... any suggestions on what else i can do rather than taking it to a shop..

aim- jdisforyou
ym- amnotazn15
 
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