Yet another idle thread

[MrPyromaniac]

Sorry this is probably my 3rd post in the last 2 weeks asking for help, but my idle has been having some erratic behavior. When I bought my car, it would idle normally until it warmed up, and then it would begin a pretty rapid but consistent hunting between 1 and 1.5k rpm. So I read a lot of other threads on here and replaced the IAVC with one from my other car that idles fine. When I turned it on the first time after switching them, the car with the idle issues would idle at 100rpm or so and then would die if I didn't give it gas. So I adjusted the idle screw to turn the idle up, and now it start at like 1.1k rpm, and then slowly go down until it's chugging at like 150 or so, but still not die. Once it warms up, the idle begins hunting again but different than before. Instead of oscillating pretty fast it slowly rises over a period of 3 seconds and then drops. The weirdest thing was that when I swapped the IAVC, the one I thought was bad actually is bad because when I started my other car had the exact same rapid idle issues I was having in the first place. Any idea what could be causing this? Everything else about the car is functional, and it has what seems like full power in all gears. The only other issue I could think of is the PGM-FI is throwing an EGR valve code that I'll be replacing as soon as I get the part; could this be causing the idle issues?

[JJ'sAccord]

Sorry this is probably my 3rd post in the last 2 weeks asking for help, but my idle has been having some erratic behavior. When I bought my car, it would idle normally until it warmed up, and then it would begin a pretty rapid but consistent hunting between 1 and 1.5k rpm. So I read a lot of other threads on here and replaced the IAVC with one from my other car that idles fine. When I turned it on the first time after switching them, the car with the idle issues would idle at 100rpm or so and then would die if I didn't give it gas. So I adjusted the idle screw to turn the idle up, and now it start at like 1.1k rpm, and then slowly go down until it's chugging at like 150 or so, but still not die. Once it warms up, the idle begins hunting again but different than before. Instead of oscillating pretty fast it slowly rises over a period of 3 seconds and then drops. The weirdest thing was that when I swapped the IAVC, the one I thought was bad actually is bad because when I started my other car had the exact same rapid idle issues I was having in the first place. Any idea what could be causing this? Everything else about the car is functional, and it has what seems like full power in all gears. The only other issue I could think of is the PGM-FI is throwing an EGR valve code that I'll be replacing as soon as I get the part; could this be causing the idle issues?

sounds like it may be the Fast idle air valve. its the other "valve" on our cars. it controls the cars idle (for the most part) until the car is at operating temp.

you can try cleaning this valve see if it helps. also you can search fast idle air valves on this forum it has been talked about extensively due to it causing people so much head ache.

take a look you can search in the google box. it should direct you on how to properly clean and adjust the valve.

[Oldblueaccord]

Also make sure the IACV coolant lines are bleed real well. I loosen the clamp and let the air escape with the car running. The bleeder on the thermostat housing wont get it.

2 other things to ask is.
1. Have you unhooked your battery, my car wont idle warm until driven about 25 miles after unhooking the battery.


2 . Is your car fully warming up when you set the low idle? If it is not then your still on fast idle mode. Car should warm up in 3 to 5 mins at 50 degrees. I just checked mine the other day.

[MrPyromaniac]

OK thanks, I'll have to try those things.

[Dr_Snooz]

There are two potential causes for the "bouncing idle":

1. Low coolant
2. A vacuum leak

[MrPyromaniac]

There are two potential causes for the "bouncing idle":

1. Low coolant
2. A vacuum leak

Coolant ended up being fine, but when I was driving it the other day around 3250+ rpm I noticed a faint high pitched whistle, so I probably have a vacuum leak. Bought some propane to find it, but are there any particular hoses I should start with?

[Shane86]

Last time mine was whistling it was at the throttle body

[Dr_Snooz]

are there any particular hoses...?

Silly boy. That's what the propane is for! LOL.

If you're hearing it, take a look at the intake manifold gasket.

[Dr_Snooz]

Also, if the coolant is low, you can't just fill it. The system must be bled properly.