99GreenEX

I have searched and read FAQ but i have not found a solution.

I want to ask some questions regarding what i have found.

Background.
Its a 99 civic EX with an 00 D16Y8 with ~60K miles on it.
I recently moved to michigan, and it is cold, but i don't see why it would make the car start to idle all whaccked out. The Y8 does not have an FITV, only the IACV.

Basically, when the car is started completely cold, it will idle at ~2000 RPM. Once it starts to warm up it will idle erratically between about 800 and 1500 RPM. Once it is fully warmed up (fan kicks on) it will idle at 1100 RPM, and sometimes bounce between 1100 and 1200.

I am not throwing a code so i believe the IACV is fine, and the coolant sensor should be fine too.

Testing and trying to figure this out i have sprayed component cleaner along every gasket and vacuum line and never hear it bog or shoot up (while it is idle steady at 1100-1200 RPM). I checked the screen on the IACV and it was clean as a whistle. I also cleaned out the throttle body.

With the intake tubing off, when the car is at idle, i can plug the IACV port, and the car will keep idling. I then blocked it off and sprayed component cleaner again and the only time it makes a differnce in idle is when i spray it around the butterfly valve inside the throttle body. Is the butterfly valve supposed to be completely closed? or is it normal for it to get air?

2 things i have not had time to do is the valve lash adjustment, and adding coolant. I noticed that the coolant reservoir was low, but coolant comes all the way to the cap of the radiator when the engine is cooled off. Could one of these be an issue? The valves sound like they are okay, ive heard them much worse on the last engine and it never had this idle issue. I will buy coolant tonite and top off the radiator however much it can, and fill the reservoir to the MAX line.

Any input as to what the problem could be would be appreciated greatly.

Thanks!

grnsihatch

it could be the throttle body. i would get a second opinion before trying that cause those can run up to $600 for a new one and you dont know how much you can trust the used ones

99GreenEX

the car is from florida, could it be possible that the intake manifold might have cracked? how ofte is it that intake might crack or warp? the gasket was replaced with the engie about 8K miles ago

spotscivic

take out the IACV and clean it with some choke cleaner. couldnt hurt. mayby will help. if you hav a MAF make shur its clean too.

99GreenEX

I dont know what kind of civic you have had or worked on but ive never seen a d16 with a MAF.

I have cleaned out the IACV.

Is the butterfly valve supposed to completely close off? like not allow any air in? because it is letting air in. I resprayed everything with component cleaner, and this time i wasnt preserving any either, there doesnt appear to be any vacuum leaks. When i induce a vacuum leak (i pulled the brake booster line and put it back on) the idle becomes erratic at warm idle too, th only problem with warm idle as is is that it is higher than usuall.

Anybody have any trouble shooting tips? i tried disconnecting sensors at idle and all of them gave me a response...(IAT, IACV, TPS, MAP).

This thing is driving me nuts and im about ready to blow the ****** up and swear hondas off for life. Never had this much **** with my mazda MX3 even... best car i ever owned was a VW 1.8T. if its idle was fucked up it knew why, CEL would come on and tell me what the prob was. I guess maybe its normal for civics to have fucked up idles...

tpr

Warm the car up completely (Fan comes on). Disconnect the IACV. Using the idle air screw (top left of throttle body opening). Set the idle to 500-650 RPM. Shut down the car, reconnect the IACV. Reset the ECU start and let it idle for 10 minutes to "relearn" the sensors. Then drive my son drive.

freds99civic

I also have a 99 Civic wih 77k on it same motor. and i have been having idle issues as well with my car. I know my car is going to idle higher when cold and when fans kick on. but even if the car is at normal running temp. and no fans are on. Suddenly it goes from idling around 800rpm to 1500 or so. Also the engine is making a looping sound. I know the IACV screen is clean. ect. ect.

The **** drives me crazy as well. when im getting food at a drive up window and then all of a sudden my car starts roaring at the employees inside the window. Lol

-Fred-