whenever i start the car when it's cold, it instantly jumps to 3000 rpm, and then drops down to about 2000, then back up, and then down....

once it gets warm, the engine slows down to about 1500rpm, but still bounces slightly...

what could be the problem? i hear what sounds like a vacuum leak down on the passenger's side behind the intake manifold, but i cannot find the leak....any suggestions?

thanks in advance

 

I would say a vacuum leak too, are you throwing any CELs? it could be the IACV, if it is throwing a code then I am sure it is number 14, the IACV...Have you driven it around the block like this or what?

 

spray some carb cleaner down around that area and find out for sure if it is a vacum leak or not. If not try seaching "idle problems" on here....it seems like every 2nd post on here every day is asking about idle issues.

 

i've been driving it for about 3 days like this, and i'm not throwing any codes...

i'll spray some carb cleaner in there to find out where this mysterious leak is coming from...

 

maybe you should think about why you are such a poonjab first and then realize that you're a smelly mesican....lol j/k mang whats up..

 

Mine did the same thing. Turned out to be the FITV (fast idle thermo valve)

 

Possiblity is that the two sensors on the TB got crossed. This will throw a code just to let ya know. Check not only hoses for vacuum leaks, but your TB and IM gaskets, they might not be on right, and the manifold to head bolts should be around 17 lb-ft of torque.

 

My car does that also, it is throwing the code 14(IACV) take out the IACV and spray down the screen with some brake cleaner or carb cleaner. Make sure you clean it very good and that should fix the problem.

 

ovbiously some kind of vaccum leak... my prelude was known for this... if it wasnt' warmed up... it would do that ...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondainspired &raquo;</TD></TR><TR><TD CLASS="quote">ovbiously some kind of vaccum leak... my prelude was known for this... if it wasnt' warmed up... it would do that ... </TD></TR></TABLE>

Actually it actually may not be a vaccum leak.

I had the same problem.

First i took my IACV off cleaned it up.. no fix

Next i started my car up with the radiator cap off (to get any air out of coolant)
still no fix.

I took my FITV (fast idle thermo valve) out and took it apart brake cleaned it all and tightened it down all the way..

Then i went to my haynes manual to adjust my idle properly..

Adjust your idle:

Turn the idle screw on your throttle body and then you haft to pull the 7.5amp backup fuse in the engine bay for 30 seconds and this will reset the idle.

Started it up and it idles at 750 constantly.. right where i want it

Refer to these threads:

https://honda-tech.com/zerothread?id=699787
https://honda-tech.com/zerothread?id=1026024

Any questions PM me or aim me.

 

very good info...^^^

 

cool man, i'll check that out tomorrow

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SpoonFedHatch &raquo;</TD></TR><TR><TD CLASS="quote">cool man, i'll check that out tomorrow</TD></TR></TABLE>


no problem, but fixing your FITV isn't as easy as 1,2,3

 

check your EACV,

it is the valve on the back of your intake manifold,
its whole purpose in life is to control that surge in your idle when your car is cold. I guess this is to help it warm up on cold days.

Whne it works properly your car should idle at 1500rpm when cold, then drop down to around 750 when warm.

if malfunctioning the idle could jet up higher, or waver up/down.

There is also another valve under the throttle body that assists the eacv in its job.

 

FIT valve fixed it for me! I just took it off and have never had a problem since. The forum mod (B18-C5) said that is not a good idea, my car runs perfectly. If he hasn't gotten his fixed yet, does anyone have any experience with this?

-Shane

 

where is the idle screw on your throttle body?

 

I had the same problem a few weeks ago the line going into the TB from the cruise control had fallen out, fixed it immediatly

 

subscribing

 

i had the same issue on my B18C.
the idle would slowly increase over the course of a month 1500, 2000, then one day 3000 rpm bouncing up and down

turns out theres a small plastic cap that screws in under the throttle body. (fast idle valve i think) and it had backed itself out.

screwed it back in, pyt a drop of loctite on it and no problems since. better than when i got the motor actually

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nighttrain33 &raquo;</TD></TR><TR><TD CLASS="quote">FIT valve fixed it for me! I just took it off and have never had a problem since. The forum mod (B18-C5) said that is not a good idea, my car runs perfectly. If he hasn't gotten his fixed yet, does anyone have any experience with this?

-Shane</TD></TR></TABLE>

Did you fix it or delete it? I've seriously considered bypassing the hot coolant that warms my intake way too much. It would solve lots of idle probems too.

 

I took the FIT valve off and put a plate in its place. Like I said, it's been a number months and I haven't had any problems to this date.

-Shane

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Turbo E 604 &raquo;</TD></TR><TR><TD CLASS="quote">i had the same issue on my B18C.
the idle would slowly increase over the course of a month 1500, 2000, then one day 3000 rpm bouncing up and down

turns out theres a small plastic cap that screws in under the throttle body. (fast idle valve i think) and it had backed itself out.

screwed it back in, pyt a drop of loctite on it and no problems since. better than when i got the motor actually </TD></TR></TABLE>

Are you talking about the plungger type thing inside the FITV? (the thing that you screw in with a flat head)

If so it didn't back it's self out they are just adjusted to spec from honda.

I actually do not know the theory on how and why this problem occurs.., but i do know it solves most peoples problems by tightening the FITV down.

 

the big white plunger does back itself off, I've seen them back themselves completely unscrewed. Honda didn't adjust it like that.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jimmy &raquo;</TD></TR><TR><TD CLASS="quote">

Actually it actually may not be a vaccum leak.

I had the same problem.

First i took my IACV off cleaned it up.. no fix

Next i started my car up with the radiator cap off (to get any air out of coolant)
still no fix.

I took my FITV (fast idle thermo valve) out and took it apart brake cleaned it all and tightened it down all the way..

Then i went to my haynes manual to adjust my idle properly..

Adjust your idle:

Turn the idle screw on your throttle body and then you haft to pull the 7.5amp backup fuse in the engine bay for 30 seconds and this will reset the idle.

Started it up and it idles at 750 constantly.. right where i want it

Refer to these threads:

https://honda-tech.com/zerothread?id=699787
https://honda-tech.com/zerothread?id=1026024

Any questions PM me or aim me.

</TD></TR></TABLE>

youre god! thanks for allowing my car to be normal again and pick up chicks and not scare them away with UNR (un necessary revving)

 

i found the answer, the FAST IDLE VALVE was stuck out....i just had to remove the throttle body and then re-screw in the plastic holder of the FIV

thanks for everybody's help!