My friend has a B17 in his car and the idle goes up and down only when the car is WARMED up.

When it's cold, the idle is normal.

The idle was normal before. Then he swapped out the turbo manfifold and the turbo but he cut his downpipe from the turbo so it's running open downpipe. The O2 sensor is about 4-5 Inches from the opening end of the downpipe. Could this effect the idle?

Also there is no CEL popping up


Modified by Mean Street at 12:19 PM 9/26/2004

 

It's not the O2 sensor. It's most likely a bubble in the coolant, something hooked up incorrectly at the TB or IACV (coolant or vacuum line), or a vacuum leak.

 

Wouldn't a vacuum leak automatically make the car idle funny even on a cold start up?

Hmm...coolant, never thought of that.

 

My b16a idle fluctuates, and my mechanic told me it was a faulty IACV,?,

 

The car idles up on cold starts making for less idle symptoms sometimes.

Because of the FITV, coolant can affect idle. That's why Hondas are notorious for strange idle problems.

I wouldn't go ahead and replace any parts like IACV w/out doing a search and trying everything else. This problem is very very common so do a search. Try cleaning out the IACV screen.

Also, your idle could be low for some reason, causing the idle to drop, then the computer kicks in revving it up, then it drops again. Could be a number of things. You have to make a checklist of all the suggestions and go through it.

 

fast idle thermal valve

 

clean out the iacv, there is a screen in the back, check for vacuum leaks by spraying carb cleaner all and around them, bleed cooling system. might be fitv

 

I bypassed my FITV. I completely removed it and sealed the hole shut with a solid gasket, some gasket sealer, and a piece of sheet metal.

 

It is the iac. Idle air control unit. It is probably broken. Take it out tear it aprart, and put it back together. it will work!

 

i took my turbo off completely because i thought i was going to sell it..i put it on along with new spark plugs and it doesnt happen any more..i have no clue,i guess it was the plugs..

 

Could it be that the radiator overflow tank is empty, the radiator sucks in air and tha'ts what's causing the FITV to make the car idle up and down?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JapAndy &raquo;</TD></TR><TR><TD CLASS="quote">Could it be that the radiator overflow tank is empty, the radiator sucks in air and tha'ts what's causing the FITV to make the car idle up and down?</TD></TR></TABLE>

that's a possiblibity only if the coolant level inside the radiator is extremly low to begin with.

 

Well, very strange. We took off the charge pipe from the turbo to the throttle body and let it idle while cold. The idle was high, then I put my finger to cover up the hole for the FITV, the idle dropped down to about 7-800 rpm and then I took my finger off and it went back up to high.

We let the engine running for a bit and once it got warmer, the idle dropped down to a nice IDLE. No more fluctuating idle. Very strange!! So then we put the charge pipe back on and the idle is perfect again....

So I'm not too sure what's wrong

My magic 1 finger touch I guess??

 

like i stated above..fast idle thermal valve..fix it

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eg6T &raquo;</TD></TR><TR><TD CLASS="quote">like i stated above..fast idle thermal valve..fix it</TD></TR></TABLE>

It works fine now

 

If ur FITV is removed, what would the idle belike?Would it be low when its cold, or high all the time?

 

If the FITV was removed, the car would idle low all the time, even on a cold start up