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Discussion Starter #1
This is my first post on this site, I'm not much of a forum person, so hopefully I did all this right! First off, I drive a 98 prelude base (automatic 4 spd sport shift). The car has always been fine, the transmission (as unreliable as I've heard they can be) has always run fine, with only few minor issues. However, lately my car has developed an idle problem. When I am in drive, say at a stop light or stop sign, my car feels as though it is trying to lunge forward, even when my foot is firmly on the brake. Every 2-3 seconds it will try to jump forward, then recede back, only to try again a second or two later. If I let off the gas, the car will idle like normal (Travel at 2-3mph) then pull back for a second like im on the brakes, but I'm not. Sometimes, when it does this, I let off the brake and my car does not even Idle up to speed like its supposed to for a second, before gaining speed and receding again. Also, as i drive the car, it seems to deteriorate. As it warms up, the throttle response gets sluggish, especially at low rpms, it will be significantly less responsive then when it is cold or recently started. It only seems to happen when I have been driving my car for at least 15-20 minutes. It also only seems to happen when it is warmer out. I've never noticed it doing this during winter season. Every where I look i have only seen threads about rough idle or idle fluctuations due to the IACV, but never seen anything about this problem that I have. My question is, does anyone think they may know what the problem is? It's not my 02's just has those replaced a few months ago. I also replaced my fuel filter, PCV, cleaned out my EGR valve, cleaned the throttle body and I've even tried adjusting the throttle cable in case that was too tight and possibly holding open the throttle when stopped. Any suggestions would be greatly appreciated! Thanks!
 

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more than likely the fast idle thermal valve .. the coolant lines running to the throttle body control this .. there known for going bad on our cars causing this exact issue ..
 

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Discussion Starter #3
sorry to press, do you know if this is an expensive fix? It sucks to have to enjoy the first ten minutes of my driving experience knowing its going to get worse and worse as i drive :(
 

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Discussion Starter #5
everywhere I look most people either say it is the IACV or FITV that cause the problem, but none of them seem to explain the problem I have. Is there any quick ways to test this yourself?
 

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a lot of time as the fitv goes bad it will act fine till the coolant comes up to temp then the idle begins to fluctuate .. there is a piece inside that goes bad causing more air to bypass it than should when the engine is warm then the iacv tries to compensate and cant .. if you let it go long enough it will start to do it all the time cold too .. you can bypass it but if you do you will no longer have a high idle at warm up .. in a lot of cases causing the car to stall on cold starts ..
 

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Discussion Starter #7
Yeah I'm not going to bypass it, I live in Maine so I need my cold starting power since I have to use my prelude in the winter. This issue wouldn't throw any CEL's would it? Mine is clear at the moment. I'll have to do research on FITV to see how much I can get one for. If anyone knows a good place price wise to buy a replacement the tip would be appreciated. I can't stand the surging and terrible running conditions after warm up...thanks for the advice though, been trying to figure this out for awile.
 
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