Idle issue strikes again

[TyronasaurLX-i]

Well I replaced a vac line and my idle was now back to normal, no more surging when going to park. Drove it around to do some errands and everything was fine. Today I decided to drive it to work and there it is again. I got an unexpected 2 hour break at work and thought I should try to mess with it again. I remembered reading somewhere about sticking your finger over a valve located next to the air filter box and seeing if it affected idle. So I started her up and she wasn't surging but was idling around 2k. Covered with my finger and it dropped to around 1100. Shifted to drive and then to park. Surging comes back. Stick my finger on it while surging and it does nothing, doesn't even feel like it's sucking my finger. Now I'm thinking this valve is the problem, but when I turned the car off and took it off it looked closed. Any insights? Thinking my idle is set too high and this valve needs cleaned. Can I use carb cleaner? It's all I got right now

[Oldblueaccord]

Well I replaced a vac line and my idle was now back to normal, no more surging when going to park. Drove it around to do some errands and everything was fine. Today I decided to drive it to work and there it is again. I got an unexpected 2 hour break at work and thought I should try to mess with it again. I remembered reading somewhere about sticking your finger over a valve located next to the air filter box and seeing if it affected idle. So I started her up and she wasn't surging but was idling around 2k. Covered with my finger and it dropped to around 1100. Shifted to drive and then to park. Surging comes back. Stick my finger on it while surging and it does nothing, doesn't even feel like it's sucking my finger. Now I'm thinking this valve is the problem, but when I turned the car off and took it off it looked closed. Any insights? Thinking my idle is set too high and this valve needs cleaned. Can I use carb cleaner? It's all I got right now


Guessing your talking about the fast idle valve its located right on the throttle body?

If you take the little cover off with two screws you can see the plastic is slotted. Lube it and use a quarter to turn it in to lower your cold idle. Thats what is used when your car is cold.

EDIT: added video.


https://www.youtube.com/watch?v=6h6Y70nxQ04

[TyronasaurLX-i]

Aha yes exactly. Silly me took my manual out of my car and was doing everything from memory. How far should I lower it? Also is there a torque spec because I just snugged the bolts back

[Dr_Snooz]

Low coolant will also cause the bouncing idle.

[Oldblueaccord]

Aha yes exactly. Silly me took my manual out of my car and was doing everything from memory. How far should I lower it? Also is there a torque spec because I just snugged the bolts back

I cant really remember maybe quarter turn at a time until you get the cold idle you want. Car has to be cold several hours to get it set up.

[TyronasaurLX-i]

Well I adjusted and got it to stop. Started to drive home and noticed a few things different. Heat would no longer blow from the center vents but it would from the sides, when I drove earlier today it worked normally so I'm not sure what's going on there. When accelerating, for example going from 50 to 55, my idle would jump from around 2250 to 2750 until I got to 55, then drop back down. It was not gradually increasing despite me barely hitting the gas. Going to check my coolant tomorrow and read my manual tonight to see what exactly the fast idle valve should be doing.

[Oldblueaccord]

Good idea less heat pretty good sign of low coolant level.

I can remember if air out the top of that thing means its bad or normal function sorry.

[Dr_Snooz]

Wait, is the engine RPM actually changing like that, or just the tach reading?

[ShiRen]

I also found that weird... Rpm is tied directly to wheel speed so that sounds a little odd. There is a reason they call them slipomatics though.

[TyronasaurLX-i]

Coolant was a little low but it didn't seem to help. Going to make a short video to post later because I have no clue what to do other than replace the fast idle valve and then adjust the idle on the throttle body. Also I don't have a tachometer it is the reading off the dash

[TyronasaurLX-i]

Short update. I found some posts from about 14 years ago and from what I can gather it is either my throttle cable is a little tight, my coolant temp sensor, my coolant has air in it, or the FITV needs to be replaced. Or a combination of these things

[Dr_Snooz]

If the coolant is low, you will need to bleed the system to get the air out. It's the air bubbles in the IACV that cause the bounce. The IACV doesn't know what to do with it. In all cases that I've seen, the bouncing idle is caused by low coolant or a vacuum leak.

[ShiRen]

Throttle cable is a really easy one do diagnose. Wiggle the cable on the throttle body and make sure it isnt tight as a bowstring, maybe back it off a tiny bit anyway, then pay attention to when you have the issue pull back on the pedal with your foot and see if anything changes.

Does anyone else seem to have an interdimensional portal in their coolant system? I doubt I am going to have head gasket issues with my head studs and its rock solid on a leakdown test. I might poop myself if I pull my carpet and find out my heater core has been leaking all along. On the bright side it leaves room to top it off with antifreeze in the winter.

[Dr_Snooz]

If you haven't replaced all those thousands of little bypass hoses strewn across the engine compartment, move that to the top of your to-do list. They are probably seeping, which is what they do before they start failing and leaving you stranded on the side of the road.