buddy, i am having the exact same problem as you and have been working on it for a couple of weeks. I have replaced the Fast idle air control with a used one, after doing so looked at my old one and the washer was all the way loose so i figured that was my problem. Im sure it would of created a huge problem, except for there must be another problem. I have replaced the IAC with a used one as well and cleaned both and have same results. I have bled the coolant and retopped. I have sprayed carb cleaner on every hose and all around the IM and TB but no sudden surging as i do. Im pretty much stumped.
When I unplug my IAC, it changes patterns. It goes from a long rise and drop to a very very short rise and drop (more of a rumble) and it does so much much faster. Now when I unplug my throttle position sensor (that is the electrical plug on the back side of the TB right??) it takes it about 10 sec...then it quits the idle surging, and it idles smoothly at a very very high idle. Prolly somewhere around 2K higher than usual (i cant tell since my tach is off). Im thinking of getting a TB and replacing it to replace that TPS sensor. One other thing, when i replaced my FIAC the water hose coming out of it was blocked by hard corrosion or something of that sort, Im certain no water was getting by at the time...it is now free flowing. Does anyone have any other suggestions?
02 sensor is fairly new, less than 4 years.
i am sure a tune up would not hurt at all. although i really doubt this is the problem. (what do i know though?)
I had a funny idle problem with my H23 and then with the H22. It was the TPS in both cases. Hook up a voltmeter to your TPS and see if the voltage drops out when moving the throttle.
well i am back again. honda said it could be oil seeping into my dist. i am going to swing by the auto parts store and pick up some tune up parts tonight. if i can keep my second job just a little longer i will order a new IAC valve.
what would happen if i just took the IAC off and blocked it?
(the night statement is untrue, i just hardly drive my care enough in the daytime to get it up to temp.)
I really feel for your guys - this seems to be a big problem with these cars when they get old. I've been through ALL of this crap years ago. I ended up replacing my fast idle valve, IAC, plumbing, bled the coolant, etc, etc, etc. What ended up fixing mine was the THROTTLE POSITION SENSOR(TPS). Its a pretty damn expensive part and is somewhat delicate. Apparantely they wear out with time. They have a variable resistor that changes as the throttle position changes and this data is sent to the ECU. When the mechanicsm wears out it sends incorrect data to the ECU and you get the bouncy idle.
Before replacing it totally you can loosen the two small screws that hold it in place and turn it. There's about a 15 degree movement allowed that you can use to tweak it. Beware - its EXTREMELY sensitive, moving it even a hair will change the parameters. Additionally, its safe to do this stuff with the engine running which makes things faster to fix.
If you have a Honda Prelude shop manual (the real one, not a crap one) you can find the resitance value of the device. It will give you the ohm value of closed and open. If these are off by even 5% it needs to be replaced.
Good Luck- hope this helps.
Brad
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Mobile Electronics Guru
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95' Si with JDM H22A/P13 ECU & JDM Climate Control
04' Volvo S60-R (Daily Driver)
The impedence of the TPS could show that its fine, but as the throttle goes from closed to open, there might be dead spots in which the car will hesistate. Likewise, if you measure the voltage of it w/ the throttle closed and open, it could indicate its fine, but in between open and closed, it could have dead spots.
You can pick up a used TPS on ebay for $30 or so. Honda doesn't sell new TPS's - you have to buy the WHOLE throttle body assembly. Also, on USDM motors, you have to cut slots into the 'screws' that hold it (Honda ground them off for whatever reason) in order to remove it.
Also, on USDM motors, you have to cut slots into the 'screws' that hold it (Honda ground them off for whatever reason) in order to remove it.
Oh yeah! I totally forgot about that! That's why it was so expensive - because the whole throttle body is like $600 or something crazy like that. I ended up getting mine off of ebay, cut the slits on top of the filed down screw heads, and then found some nice phillips head screws to replace them with so I can adjust it whenever I want.
Its all coming back to me now....
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Mobile Electronics Guru
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95' Si with JDM H22A/P13 ECU & JDM Climate Control
04' Volvo S60-R (Daily Driver)
Well yesterday I disconnected the IAC. Car idled like a champ right around 500 rpm. Ran great above 1500-2000 rpm. Unfortunally it was a little rough and jerky just cruising around at slow speeds. I live/work on a military base so unless I go off base my car never sees above 35, with most driving done between 20-25mph. This was right in that zone. It also triggered a CEL.
Today I plan on dragging Pa out there while we check the TPS.
you can make a block off plate for the iacso you can leave it pluged in and not throw a code. get some sheet metal cut out to fit and use liquid gasket goopy stuff.
not the best but will work till you can afford a new one
Well yesterday I disconnected the IAC. Car idled like a champ right around 500 rpm. Ran great above 1500-2000 rpm. Unfortunally it was a little rough and jerky just cruising around at slow speeds. I live/work on a military base so unless I go off base my car never sees above 35, with most driving done between 20-25mph. This was right in that zone. It also triggered a CEL.
Today I plan on dragging Pa out there while we check the TPS.
Did you replace it? Sounds like the IACV could be bad.
I haven't taken the time to read through all the posts, but go through the items in the Idle sticky in the GD. A lot of things can cause this... not to mention an interaction of things.
Keep in mind that if the base idle is set too high or too low (note that if you set the idle speed per the book with the IACV disconnected it should be set right, sounds like it is) that the IACV will bounce as the ECU runs out of adjustment (just cycles back to it's min or max value).
hum... thats something to look into. although it was acting up before i mess with the idle any. although this could cause some of the problem as well. to readjust the idle you have to disconnect the battery correct? i think that was what i did last time.
thanks.
i never did make it outside to test the TPS. maybe oneday.
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