aneurysm

Agreed - I'm voting TPS problem.

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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)

mdpc20653

trade it for a 5th gen....lol......maybe its the iac? tps more likely

marcucci

That's the proper idle adjust procedure, at least on the 5g. Unplug the IACV and adjust the idle to the setpoint (I think 550?). The IACV increases the idle from there but the base setting is made with the IACV disconnected. I'd have to check the manual for the proper 4g procedure.

The idle does not need to be reset after a battery disconnect.

cifer6425

here is a question for y'all.

I went out to the car yesterday and tried to check the TPS with my trusty multimeter. Is there any easy way to get my leads on the TPS leads? i guess all of ours tps sensor are turned down slightly, making it super fun to try to make contact with. Does the car need to be at normal temps when checking the voltage on the TPS sensor?

Thanks

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Custom Shift Boots ||| My Car

G_Loc

What I did was stick safety needles into the connector where the wire enters. Just get them far enough in there that you register some voltage. To these I hooked up a pair of alligator clips so I could have my hands free. Be careful not to short anything out!

The wires you need to check are the bottom one and the middle one. If its not the middle one, its the top one. It needs to read about 0.5v with the throttle closed and about 4.5v at the throttle open. Make sure to also measure the voltage as you slowly open the throttle. Once again, don't short out the pins! lol

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cifer6425

This is the part where yall get to say I told you so.

Tonight I went outside and fiddled around with the TPS. as I was doing so a memory came back of doing it before. so no formaly testing but after loosing up the bolts and readjusting the tps some, it APPEARS my idle problem is gone. so one day soon I will buy a new TPS cause I am sure mine is on its last leg.

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juliangungho

Ok I am over here in the uk and I have seen this on the preludes F and H series motors and rovers etc. I see from the threads that every one has checked the obvious except one thing. I have seen this problem so many times now over here and the first thing I do is check the coolant pipes running from the thermostat feeding the valves on the manifold. Disconnect the pipe on the throttle body and make sure the nipple is not blocked with rust. Secondlly the iacv and the other valve are connected in series via a rubber and metal pipe. Disconnect one end and see if you can blow through it and see if you have a blockage. On the cars that I have done I have always found either the thermosat nipple is blocked or one of the pipes is blocked. The car will not throw a fault code because the fault is a mechanical issue. The ecu sense the coolant temp and adjust the idle as such but the mechanical sensor adjusts it again hence the bouncing revs when the car is hot. It wont do it when its cold because both mechanical and electrical sensors see the car as cold until things warm up.

gota be worth ago chaps.


julian

aneurysm

TPS - I(WE) TOLD YOU SO!!!!!!!!! =)

Congrats on the fix and welcome to the "Bouncy-Idle Troubleshooters Club"

-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)

slipknot95758

have fun finding a tps cause they are rivited on in the states so you need a whole tb

you can go tp a pick n pull or local type deal with a drill and get one off ofe just about any honda that is fuel in jected though

then tap hole in your tb and use bolts or screws to hold it on

G_Loc

They aren't riveted. They are screwed in with the heads ground off.

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cifer6425

yea yea...
once i started loosening the bolts i remembered thats how i fixed it before. getting old and forgetful sucks. i think i may go ahead and pick up a newer used TPS anyway.

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Custom Shift Boots ||| My Car

cuzimbob

Does your battery light come on while it is idling rough? Mine is, and i can make it quit if I turn the key off and back on real quick. I'm stumped on my issue.

SeqInjection

Engine revs constantly while sitting at idle? Stopped in traffic, etc.

It's probably the IAC or Idle Air Control Valve.

The IAC has a seal inside that will unthread its self thus letting more air in when its not suppose to and cause the ECU to get confused leading to the surging idle. Sometimes it just gets dirty and needs to be cleaned.

The 4th gen IAC is right under/near the throttle body at the intake. It has two hoses attached to it and screws to hold it in place.

Remove the IAC and open the cap which consists of a few screws and screw the seal back in or take the spring out and clean it and the valve itself with some injector cleaner and put it back together. This should stop your surge.

There are a few other things that can cause this same symptom. Ranging from a hole/leak in a vacum hose to air bubbles in the coolant.

If the IAC fix doesn't get you straight, try checking all the vacum hoses and try bleeding the coolant. These too could solve your problem.

Honda Prelude Forum - PreludeDriver.com • View topic - Idle Surge

cifer6425

on my car i find the TPS get loose and will move around slightly. when i get the TPS back in the correct position and tighten the bolts down again, i am good to go. so far still going good since 2007.

maybe it will help someone else.

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Custom Shift Boots ||| My Car

preludatic

holy thread revival

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