ok, i finally saved up enough moolah to do a nice extensive tune up on my 4th gen SI, but before i did it my car started having this strange idle issue. it revves up from idle (about 1k) to almost 2500rpm . it wont do it when cold, only after the engine has warmed up. i replaced fuel filter, plug wires, plugs, oil, oil filter, the entire distributor assembly (cap/rotor came with it) yesterday and its still revving. i called a mechanic buddy of mine and he said its my throttle position sensor. its a dealership only part, so its gonna be pricey.

anyway, has anyone else had this problem? i just want to make sure im replacing the right part and not spending like 5-600 bucks on a bunch of sensors that i didint really need to replace.

oh, the car has approx. 145k on the engine, timing belt/tensioners were done last year if that helps at all.

 

First things first. Most idle issues are caused by a vacuum leak. Check your vacuum lines and gaskets for leaks first. If all is good check your IACV and FITV. Once they are checked and you still have the problem then you may want to look at the TPS, although you would probably be getting a CEL if it was bad and you would have some hesitation. Do you have any CEL codes? Start there and then check back.

 

hesitation and gas milage are baaad, but no CEL at all. what are the IACV and FITV?? i just dropped into the local dealership and talked to one of the techs there. guess that sensor only comes as part of a new throttle body (700 freakin bucks too) and since im not very mechanically savvy i scheduled a diagnostic for next week. deff worth th 93 bucks to see if it is indeed that sensor and not something more affordable. if it is the throttle body i might just go aftermarket.

 

FAQ section has a lot of useful information:

https://honda-tech.com/zerothread?id=1979500

 

Just so you know, most honda mechanics know shiet. They will probably keep swapping parts untill they finally get it right.

Fast Idle Thermo Valve (fitv) and Intake air control valve (iacv)


FITV is right under where your intake pipe meets your throtle body/plate. It has a few coolant hoses plugged into it. If the idle is only fluctuation when at opperating temperature its not likely a vacuum leak. A vacuum leak would cause Idle fluctuations all the time would it not?

There are lots of topics for troubleshooting idle fluctuations. I'd look it up in the archives section in the Search (big red search).

So to be certain of what your saying it idles at lets say around 1600 while warming up and maintains around there slowly dropping untill car is at normal opperating temp? Than when its there, the idle jumps around from 1100 up to 2500 (back and fourth) or does it go up to 2500 and stay?

And about that tps, you don't need to buy the whole throtle body. Those stooges are trying to pull one on you. Don't deal with dealerships. I wouldn't even let them diagnose anything either. That 93 dollers could be spent better elseware.

And also, about you going after market intake. They don't come with sensors. They usually don't even come with the ports to install your sensors etc. You need to have the ports added in after by a machinest (if you don't have the proper tools)

So in the end, if you need a sensor, buy it used off H-T, or off Ebay.

Either way, start by looking for vacuum leaks because that costs nothing. Than I'd check your intake for loose clamps. Than I'd check your fitv, and iacv and make sure they are sealed with your throtle body propperly. Than, the physical components might need to be inspected or swapped out temperarily for known working parts.

Last option/worst case scenario is to buy a whole intake/throtlebody with all sensors used off H-T or ebay. They sell from 50-150 bucks. Than, it would sound like you'd need a shop to install it, unless you want to learn how to do it yourself. At a shop I believe its a 4 hour job to remove intake, so total labour would likely be around 7-8 hours and cost upwards of 600-700 dollers plus the intake.
good luck

 

cool thanks for the posts guys.

as to the link to the idle repair thread that dixxon posted, if i plug the upper left hole the problem stops immediatly. what does that hole lead to?

the problem is that i start the car, it sits @ 2k till it warms up, drops to just under 1k @ normal running temp and then starts jumping fairly fast (say 1 rev every 2-3 seconds) to around 1.5-1.7k.

checked all vac hoses and gaskets, and all are sound. gonna pull EGR, FITV, and IACV this evening and try to clean em up... i think i might have a clog somewhere, i noticed alot of dusty residue inside my intake piping, so maybe my CAI filter needs to be replaced (it was a brand-X cheapo anyway).

the only reason im taking it to honda is because i dont have a code scanner to check sensors and i dont really have a safe place to pull everything appart. only got a covered parking stall and thee guys in the stalls next to m are idiots and would prolly hit me if i were to work out there.