Hey, I have a 96 civic LX. I'm having a problem with my idle it, it drops pretty low around 100-300 RPM. I tried cleaning the IACV that didn't do anything, In the process of cleaning it I broke 1 of the 4 bolts that attachs the IACV to the throttle body. I figured that wouldnt really matter since ther are still 3 bolts attaching the IACV.

I tried seafoaming, cleaning out the intake area. Nothing can get it to rise and stay there.

When I adjust the Idle set screw, that actually works for about 3-4 days, after that it gets lower and lower each day. until its about 200-100 rpm.

My friend said I probably have a valcum leak somewhere?
Another friend said Hondas IACV usually go bad after 10 years, and I'll probably have to replace it.

AnyHelp?? thnx

 

Is the CEL ON?

If you disconnect the IACV connector while your warm engine is idling, does the idle speed increase? If not, the IACV may be bad.

Is the PCV valve clogged?

 

clean the fast idle valve dealy under the TB.

 

96 and up dont have FITV but i would try a new IACV if you can get one for cheap. If you after you clean it it works for a few days then goes back i would def. check that. but good luck man bad Idle problems suck.

 

Um, My CEL isn't on. but how I do i check if my PCV valves are clogged?
thanks for the help so far.

 

pull the pcv. and shake it....if it doesn't rattle then it's clogged. you can either 1. clean it out till it rattles again, or 2. buy another for $2.00

 

my car was doing this. i unplugged the idle position sensor and plugged it back in and it worked. give it a shot

 

im sure the 96 civic majority of themcame with a 3 wire iacv which you need to convert it to a 2 wire iacv
http://www.ff-squad.com/tech/wiring/...-98_a-plug.jpg athe the ecu plug
and then you get a 2 wire and color match blu-blu and yellow-yellow

 

false. this is a terrible idea.


first you need to fix that bolt you broke. 3 will hold it on, but it's gotta seal so you need all four.

codes are very helpful in determining what's wrong with a car. check the code, and fix the issue there before trying to troubleshoot the idle. or if it's related, you'll get a better idea of what to fix.

there is a proper procedure for setting idle on a computer controlled, fuel injected car. it's not as simple as adjusting a carb on a moped... you've got to have the ignition timing right first. then, with the car warmed up, and all accesories off (including the rad fan), unplug the IACV. idle speed should be 750 ±50. if not, adjust idle screw in 1/4 turn increments until it's right.

you may also want to check condition of your "tune-up" items.. cap, rotor, plugs, plug wires before trying this.

 

Check all your vacuum hoses carefully for any signs of splits or leaks, also pull your TB and get a new gasket, I had the weirdest idle ever for around a month after my swap and that was the problem, but yea also checkin for codes is a must, thats the 1st thing to do imo. theres tons of threads on this if you search youll find the problem, and good luck.

 

okay so i put a new pcv valve in there, and it made my idle BETTER. I idle around 400-500 now instead of 100-300. But i want to get it to the right mark of 700, I think i have a leak somewhere? I would get the 4th bolt to seal my IACV, but when the bolt broke half of the bolt is still in the throttle body.
If i wanted to replace my IACV, would I have to get a new Throttlebody?

 

If you disconnect the IACV connector while your warm engine is idling, does the idle speed increase?

 

As RonJ is asking...when your motor is fully warmed up and you unplug the IACV connector - does the idle increase?

Also, which screw did you use to adjust the idle? Hopefully you didn't mess with the throttle plate stop screw. Troubleshooting a 3-wire IACV idle problem is not exactly the same as a 2-wire setup...nor is setting the idle either (you don't unplug it like a 2-wire setup).

serio_ENDLESS: Nice link - wrong thread to post it in.

 

same thing is wrong with my car i had the same type thread up..noob question what n where is pcv valve?

 

PCV = positive crankcase ventilation.



Part #3 is the valve.

 

make sure you burp the whole coolant system very good. iacv sits higher than the top of the radiator and air trapped in it can cause it to misread coolant temp.

 

Alright so I spoke too soon, Installing a new PCV valve didnt do much for my idle, it is still idling from 200-300 RPM. Is there any possibilities of why my idle is low?

 

umm, which screw is the throttle plate stop screw? The one i adjusted was the one where you have to adjust the nut, and use a HEX set to turn the screw. Its the one thats really near the throttle cable.

 

Wait.. Dropped to 100-300 RPM???? I don't think I've EVER seen a honda IDLE below 400, they usually stall! Factory procedure to set idle is to start vehicle and run till warm (Coolant fan runs) Shut vehicle off.. Disconnect the IACV, Hold your gas pedal to about a cruising position and start your car.. After it starts, slowly release the pedal till the engine comes to an idle. Turn set screw to 450-500 RPM and shut off engine. Plug in IACV and restart vehicle.

If you're having a LOW idle problem ALL the time, you have some serious problems..

When the car is cold you should idle around 1200-1500 regardless of IACV operation.. If not, your cold air bypass valve is Effed..

After the car is warm, idle operation is controlled by the IACV ONLY.. If you can not adjust your idle so it is within spec (too high) you should look for vaccuum leaks.. Start by listening.. Then try plugging the air bypass port in the snout of the Throttle body with your finger (Just before the butterfly valve in the throttle body).. If idle drops within range, your cold air bypass valve is faulty or needs adjustment.

I don't think I've ever heard of a "Low idle" problem unless the IACV just DIDN'T work.. Either mechanically or electronically.. But you'd only notice it AFTER the vehicle is warmed up.

Surprisingly enough, try checking fuses.. I'm not positive, but there was a problem I had where I had a bad O2 heater that shorted out.. The car would run, but the 02 would pop a fuse that ran all kinda stuff.. I wish I could remember, it might come in useful.. Perhaps the 12v O2 sensor heater circuit in this car is related to the 3 wire IACV?

It's worth a shot.. ?

wouldn't hurt to look for frayed or cut/damaged wires in your harness either.. Particularly around your engine harness ground on top of your thermostat housing. Those are commonly damaged areas electrically speaking.

 

We're dealing with a 3-wire IACV here. Would you people quit giving this person info concerning a 2-wire? And anything related to FITV's and cold air idle valves too? The **** doesn't exist on his engine.

But yeah...that's the wrong one to adjust...and now you've effected the TPS output. The screw you adjust is under a plastic cap (I think on firewall side of throttle body). The nut you adjusted is used to keep the throttle plate from returning to a fully seated position, because if it was allowed to continuously do that, it'd round out the bore and cause a perma-vac leak. Speaking of vac leaks, did you get that 1 of 4 bolts that snapped, replaced? You gotta fix the root of the problem...there's a reason your idle got low and it wasn't because either of those screws needed adjustment.

And is this a stock car we're dealing with...or has some mods? How many miles?

 

When I removed the IAT (Intake Air Temperature) sensor on my 99 civic it started idling low and it showed a CEL. Once I reset the ECU with the IAT connected it started idling normally. Just an idea. Don't know if this is what's wrong with your car. It could be many things.

 

Dang, that sucks that I adjusted the wrong one, But when I adjust the throttle plate stop screw, it seemed like it works for about 2 days. But The reason I didnt think the IACV is faulty is because my idle was really low before I broke a bolt for the IACV.

 

I'm so stuck.. I don't know what to do first, I dont think I can just replace the IACV, or just add a screw in there, I might just have to buy another throttlebody. If I had a leak somewhere within my valcum lines where would they be? Is there anyway I can undo the damages from adjusting the throttle plate stop screw?
and how would u properly adjust the "idle set screw"? I heard that it is behind the throttlebody on the firewall side.

 

the throttlebody "Stop screw" adjustment is simple. You want the throttle body to be as closed as possible without sticking. usually you can back the screw out till it doesn''t touch, Snap the throttle closed so it sticks and slowly turn the stop screw in till you hear the butterfly "pop" open.. lock the screw and test operation to make sure it doesn't stick after being snapped shut.. your TPS voltage should read .45-.50v on the signal wire.

As for your idle setting and 3 wire iac.. I couldn't tell ya.. I don't play with Disposable-D's..

 

sux i have a prob wit my iac also and need help ive took it to a couple of my mechanics and there stumped i put a s2 mani on my y7 and switches from the 3 wire to a 2 wire iac and now im getting a code 14 and cant find the prob when my rpm hits 1800 it sounds like a 2 step HELP