tegboi- Thanks for helping… I’ve checked all the vacuum hose, Brake booster hose, and what is check valve? nothing seems to be working… I have feeling there got to be another air getting into the intake tricking the ECU or something. The IACV seems to be working since when I turn on the a/c it raised the idle so that shouldn’t be the cause of the bouncing idle.
90red - the check valve is the plastic piece between the 2 hoses from the intake manifold to the brake booster. im just throwing ideas out there…
how’s condition of the motor? tuned up recently? ever run seafoam through it? cleaned out the injectors?
The motor was rebuilt at 189,900 miles and it’s at 245,000 miles so it’s still in good condition. I did the tune-up on everything at 225,000 miles and put in lucas fuel injector cleaner in the tank once a while not seafoam never heard of that? It has always done the bouncing idle ever since sometime it doesn’t mostly in the summer it doesn’t do that just when it’s cold out. Right now it’s at the worst condition than ever bouncing all the time now won’t stop at all. I didn’t know what that little plastic thing was for between the IM and brake booster now I know it’s a check valve that’s interesting. I’ve never messed with that should I look into that? Also the brake booster has been replaced three times and everytime I play with the brake pedal like pumping it at stop light the idle raises and lowers is that supposed to do that or the check valve at fault?
pumping the brakes alternating the idle can be caused by a bad check valve. the check valve is a plastic piece that 2 hoses clamp onto, and it is suppost to let air in one direction only. if it is damaged, it can/will let air travel both ways, giving you a bad idle sometimes also. just check it out, take it out, blow one way, and blow the other way, make sure air only travels one way. if it travels both ways, or even a little… replace it.
Man! for 3 days it has been going downhill from there! I changed the header back to factory stock and put back the stock intake since I’m going to use the performance parts on my other honda for racing. Changed the check valve, ICAV(cleaned), FITV(screwed all the way in), tb,injector, and dist. nothing seems to improve. I must have some type of air going in the IM somewhere! Other night I went to the track to see how much difference the car will run with stock factory equipment than aftermarket… surprisely it did not make a difference! I ran 9.88 at 70mph in 1/8 mile verse my best with bolt-ons at 9.77 at 69 mph? What is going on! It seems the mph is better with factory equipmment on there than aftermarket. Then after the first run of 9.88 it boggs bad like something was missing bad so I had to leave home to figure what was going on. After 4 hours of troubleshooting I came to find # 3 spark plug wire was bad (MSD wire) so I put in stocker in there runs smooth but still bouncing idle is starting to annoy the hell out of me! 
I give up on it ha! Any idea what could be something I missed?
idle troubleshoot
ok here is the deal. my idle doesn’t go up it goes down. from 1500 to 1000 after it has warmed up. i have no clue what is going on. i tightened my throttle cable. and then the problem came about i think. is there anything you might know what to do to fix this so i don’t have to loosen my cable. thank you.
DougFerbs, your idle is perfect. There is nothing wrong. It’s supposed to idle around 750-1000. It idles high at start to warm up.
no no no no. when my car warms up from driving or just sitting there, at 1500 it drops down to 1000 and goes back up. idk wtf.
Oh, you didn’t mention that. Basically that’s what this thread is about, read the first post, it has a lot of info. My car did that for a while and has now stopped all by itself, miraculously. I’m not arguing. I think what happens is basically, the IACV tries to close to drop the RPM when the car warms up, and then for some reason it opens back up again because it’s confused. This can be because it’s broken or something else is confusing it. Make sure to check all the things mentioned in the first post in order, and you’ll find the problem.
good right up man and thanks. From doing what you listed step by step it seems that my IACV is bad. I have a few laying around from other tegs so once the car cools, I’ll swap them out.
idle adjustment
ive been lookin but i cant find how do u idle adjust which way do i gota trun the
skrew to my idle can go higher rite now my idle is to low
this is all very nice but how about aftermarkets throttles? i have power industries 68mm throttle and it does not use the FITV valve so in the morning when i turn on the engine i have to rev it to 1500K or 2000K in order to warm it up, otherwise it would just shut off, i guess there’s nothing i can do about it or can i???
i hear a sound on the IACV…
My Car Has A Bad Idle And I Check The Two Holes In The Intake And Wen I Put My Finger In The Top Hole The Car Turn Off…what Could Be The Problem…and I Also Hear A Noise In The Iacv…need Help…
Already Clean My Iacv!!!
I Already Clean My Iacv And Nothing Happens…now My Two Holes Sucked Air And I Put My Finger On It And The Car Turn Off…why…
This is great!!!
I was reading this post and i am happy to say that this will be a big help to maybe solving my problem with the bad idle syndrome. It does suck when my teg idles really hard at a light or sitting in a parking spot, but hopefully with the help of your post I will solve the problem and be happy with the results.
Thanx in advance, you rock:rockon:
b18a in 90 LS
is the top port supposed to stop sucking air when the car is warmed up? got the idle back down to ~750 or so after adjusting FITV, but that top port just sucks air big time - almost whistles its so loud with the air cleaner hose assy pulled off. If I put my finger over the top port when warmed up then the engine wants to die
same thing here, its sucking air so loud, except i have a 92 ls. i have a slight idle flucuation from like 750-900, trying to steady it up, what do you think?
thanks man this worked great after tried the iacv i found it was the tps
pics are dead :argh:
I read most of the problems where it can go wrong. Common problems for people are if they go over a certain RPM like for example 3k? The tach bounces… My problem is still here and has somewhat gotten worse after installing my Short ram intake. It would bounce from regular 800-1500k then in that same pattern up, down, up down. Before w/ my stock intake it would do that but it would settle down as I came to a stop. After installing it it would do the same up, down from 800-1500k. And this time the idle does not settle down. I’ve left it after running it for about 20mins. Left the engine on and idle would never settle. What could be the culprit? I’m not an expert and not sure about tampering with all those things.
what happend to the pictures!!