Lude Generation

As some of you may know, i have been struggling with a bouncing idle issue for quite some time now. i bought a second hand fitv that was supposedly in good condition, fitted it and still had the same issue, but even worse. i dissasembled and cleaned my old fitv and swapped them, same issue. dissasembled and cleaned the "new" one and swapped them, same problem.

a coolant hose from the throttle body split when i was playing around, which i replaced and was half hoping might have been the problem, but still got the same issue. havent got round to replacing the fitv to themostat hose yet, but thats next on the list.

If that doesnt solve the problem im not really sure where to go, hence need some info. with the intake off, if i plug the lower port with my finger, there is vaccum and no change in the idle.
If i block the upper port, the revs drop down and become stable. which im led to believe is a problem with the fitv itself. but could it still be caused by a coolant issue? split pipe or airlock?

What does blocking the upper port actually do to the fitv? like is it causing the valve to stay open or closed? can it still be a problem with pipes/air in the system or does it point 100% to the actual fast idle valve?
i came accross this guide:
http://www.preludepower.com/forums/show ... p?t=302658

What effect on the engine is this going to have? is it safe to do? because i cant afford the 400 quid honda want to a new fitv.

Just really want this sorted now as its starting to drive me mad!

ive had many many issues with bouncy idle matey, and the last two times it ended up being the inlet mani gasket and im afraid taking the inlet mani off while still in the car is a ball-ache

if you've done the IACV and FITV replacements for known good ones i'd try something else.

have you cleaned you EGR? that could cause it. checked all the vacuum hoses for sure? i would also do a coolant flush, refill and then bleed for airlocks.

Here is some info fro the wiki
http://www.ludegeneration.co.uk/honda-p ... -t758.html

also there is are a couple of gaskets on the iacv which you could check - the one at the bottom of the iacv is often overlooked.
and your checking all the hoses as they can have pin holes in them which only show up under pressure - ive replaced these hoses with oem parts but tbh you could just use any right sized hose rather than wait for Honda to get parts in. You will need a mate to help you check for leaks - get him to rev the engine whilst you move all the hoses about

Drax wrote:ive had many many issues with bouncy idle matey, and the last two times it ended up being the inlet mani gasket.


have you cleaned you EGR? that could cause it. checked all the vacuum hoses for sure? i would also do a coolant flush, refill and then bleed for airlocks.

If it was the inlet mani gasket, wouldnt it still be bouncing with the upper port in the throttle body plugged?

Egr valve is blanked off and i have bled the coolant system. I had a problem for a while of the resevoir backing up and just steam coming out of the coolant bleed nipple. Seems the coolant is flowing ok again now though.

vanzep wrote:Here is some info fro the wiki
http://www.ludegeneration.co.uk/honda-p ... -t758.html

also there is are a couple of gaskets on the iacv which you could check - the one at the bottom of the iacv is often overlooked.
and your checking all the hoses as they can have pin holes in them which only show up under pressure - ive replaced these hoses with oem parts but tbh you could just use any right sized hose rather than wait for Honda to get parts in. You will need a mate to help you check for leaks - get him to rev the engine whilst you move all the hoses about

I bought new gaskets for that iacv some time ago when i thought ir was that causing the issue. Next step is replacing all of the coolant hoses around the fitv area, but the main thing i was to know is if it can still be a coolant problem when it stops with the top oort of the throttle body plugged? Cause i dont want to go replacing all the hoses if that indicates its definitely the actual valve.

Bleed, bleed and bleed the system again. Any amount of extra air in the coolant system will cause a bouncy idle.. I remember having a right nightmare getting my bb4 bled up properly.

bb1boy wrote:Bleed, bleed and bleed the system again. Any amount of extra air in the coolant system will cause a bouncy idle.. I remember having a right nightmare getting my bb4 bled up properly.

Yeah im figuring there is some air in the system, but i cant work out why blocking that top port on the throttle body would stop air in the coolant being a problem?

Yeah, that I don't know, I'm afraid..

bb1boy wrote:Yeah, that I don't know, I'm afraid..

Yeah me neither! Lol. Thats why im hoping someone xan tell me exactly what covering that hole does! I dont wanna go bleeding for hours and replacing all the pipes if its definitely the valve.

So from looking at the service manual page, im presuming that top port in the throttle body is the port the takes the air through the fitv to bypass it into the intake mani. and a correctly functioning valve would then close when the engine is warm and that port would no longer be sucking air.

So im guessing that because blocking the port with my finger lowers the revs and smooths the idle, that the themowax plunger isnt functioning properly and isnt closing the valve when the coolant is warm, causing the revs to jump right up then drop back down to where they should be.

Im also guessing the guide i linked to is going to force the fitv to the closed position permanently which will fix my idle problems.

But what effect will that have on things when the engine is warming up?

Can anyone confirm that my thoughts on this are correct as im really using a lot of guesswork here!