Bouncing Idle

[GeoffM]

Bled the cooling system, I couldn't tell for sure, but it didn't seem like there was any air in it. It wasn't completely cold though, so I'll try again tomorrow.
It seems to be linked to my A/C and blower motor.
A/C: Because the fans don't turn on when I hit the A/C button. IIRC, they're supposed to turn on right away.
Blower motor: Not consistently, but there was a period today where if I had the fans on, the idle bounced. If they were off, no bounce.

I checked ALL my fuses. Nothing was blown. I have the TB cleaner, and I'll probably get it tomorrow morning, but I doubt it'll work.

I've also noticed that this only seems to happen after I take it out of drive, and once the engine is warm.
Any more suggestions?

Edit: Just opened helms, I want to make this clear:
My fans DO work (both of them) but they take a while to turn on, and they do not turn on when I hit my AC.

['93CB7Ex]

you might have a cts thats going bad. or whatever switches idle up when it loads up ie a/c is not working.

[GeoffM]

you might have a cts thats going bad. or whatever switches idle up when it loads up ie a/c is not working.

I think that's the IACv. Helms has given me a few very good ideas. Most are the IACV or the ecu though. Before replacing the IACV, it told me to check something to do with my AC, which made me happy! Unfortunately I don't think I'm properly equipped here. I'll give it my best shot then I may have to make a trip to the dealer.

[GeoffM]

I pulled my error codes in hope that it would tell me something else. All I got that was useful was code 14. That's IACV, but that is likely from those times I simply disconnected it while the engine was running. Also a bunch of old ABS codes. Hopefully tomorrow after work I can get into diagnosis more. I'm taking a trip at the end of the week and I'd like it a lot if my A/C worked!

Here's the code video, if you're bored.
http://www.youtube.com/watch?v=z6nUBv9Rb48

[GeoffM]

Updates!

New info:
A/C doesn't work because there is NO freon.
^^^Upset about that. Because I probably nicked one of the lines when I did my ABS pump or took off my bumper
Re bled the coolant when it was bone cold. Last time I parked, washed my car, then bled. Coolant was still VERY warm.

Can't tell if the re-bleed helped, because the problem is occasional and only happens when warm. I haven't had to go anywhere today. I'll update later.

Side question: It'll be at least 2 weeks before I can get my A/C looked at. Will the cooling system being empty for that time do any damage?

[GeoffM]

Re bleed did NOT help!
Mildly urgent issue thread is here

I'm in the process of uploading the idle bounce video.
Once my engine cools (hose on the rad), I'm going to replace the FITV.
I'm hoping that fixes it, because what I have now is dangerous.

[GeoffM]

The current situation:

I've figured out how to stop 50% idle: Unplug IACV.
I get other symptoms when I drive like that, like choppy driving, but it's safer than idling in to the car in front of you. Or idling your way to 50mph!

Anyway, I did that and drove for a bit. Some occasion idle jumps. maybe about 50 rpms.
BUT: Later in the day I drove with it plugged in. Everything was fine until the engine warmed up. Then it was back to good old idle bounce, but no sky high idle.

I'm going on a trip tomorrow. When I get back, I'll replace the IACV and see if anything changes.

[GeoffM]

New IACV, and a better idea of my symptoms:

New IACV makes a lot of things better, but not perfect.
Idle is more controlled, almost normal.
As the car heats up, it starts to mess up. Idle bounce and high idle (2100).
When I park after I drive, it will usually do it(bounce). It seems to correct itself quickly though. When I finally popped my hood to take a look at it it seemed to only do it when I put it under extreme electrical loads, ie the fans we on, I turned my headlights on and off and hit the window switches. Idle jumped and started bouncing, I unplugged the IACV and it fell, did the mini bounce, then stopped.

So, electrical problem somewhere, or did I get a bad IACV? I got it from the junkyard.

[batever]

Do the actual electonic diagnostic on the IACV, (using a voltmeter and an ohmeter) don't just run out and buy a new one. Reason: there may actually be a problem with getting proper voltage to the IACV itself and replacing the IACV would have no effect if that's the case, and if you didn't know that there can be a voltage supply problem to the IACV then you would end up going on another tangent.

Failing main relay can affect the voltage to the IACV.

As to rpms sticking at where you are, make sure your throttle is not sticking.

good luck.

[batever]

Everything was fine until the engine warmed up.

Points, perhaps, to the main relay.

Do that electrical check on the voltage feed to the IACV.

You have only 131K miles on your car? that's amazing.

[GeoffM]

Points, perhaps, to the main relay.

Do that electrical check on the voltage feed to the IACV.

You have only 131K miles on your car? that's amazing.

I'll do the electrical check, probably today.

Everything is also fine once it's warmed up and I'm at highway speed. If I drop down to stop and go traffic then I start getting problems.

[DarkHusk11]

I had similar problems and it turned out to be clogged up coolant hoses that go to the iacv. I dont know if you looked into that yet

Actually alot of my hoses were clogged.. Not just the ones that went to the iacv

[batever]

haynes:

IAC system check

Idle speed is controlled by this system, which is actualted by the ECU according to running conditions of the engine (A/C, power steering, cold and warm running etc.)

CHECK

disconnect the elect. connector from IACV and measure the resistance of the IACV. it should be between 8 and 15 ohms.

check for continuity between each terminal of the IAC valve and ground. there should be NO continuity. If there is, replace.

4. turn ignition to ON (not running) and measure voltage between the yellob/black (postiive) terminal and the black/blue (neg) terminal. There should be battery voltage.

5. If the voltage reading in (4) is not correct, have the electrical circuit for the iacv diagnosed by a dealer service dept or other qualified repair shop. NOTE: check the main relay for a possibel failure or a damaged connector.

ALSO:

FAst idle thermo valve. allows additional air to bYPASS THE ntake manifold to increase the idle speed. Once engine reaches operating temp, the valve closes, returnign the engine to normal idle.

1) start engine and allow to idle.
2) remove the FITV cover and place your finger over the valve seat. you should feel some airflow there. If there is none, replace the FITV.
3) If there IS airflow, warm up the engine and check again for airlfow. There should be none. If there is, replace.


ALSO
Starting Air Valve

11) using a hand held vacuum pump, apply vacuum to the starting air valve. and check that it holds vacuum. if it doesn't replace.

[GeoffM]

I never thought to look at Haynes, only looking at helms instead. Once it stops raining, I'm going to go do that.

[batever]

When I finally popped my hood to take a look at it it seemed to only do it when I put it under extreme electrical loads, ie the fans we on, I turned my headlights on and off and hit the window switches. Idle jumped and started bouncing, I unplugged the IACV and it fell, did the mini bounce, then stopped.

So, more interpreation/guessing: It sounds like perhaps voltage is getting through to the IACV when it shouldn't. Perhaps the main relay is an issue.

also, there may be overall poor voltage control in the electrical system. under heavily varying load.

Think about the ECU, the main relay, and also the voltage regulator in the alternator as possibles as well.

I speak as one who has little practical experience with these systems (but I read the repair manual a fair amount).

My own car has the same or a similar problem but it hasn't been dangerous and I haven't gotten around to dealing with it but I've been making my plan of attack. ONE BIG reason it hasn't been dangerous is because I have a standard transmission and have full control over what power gets to the wheels in most situations--and when slowing down to a stop in traffic the clutch pedal is in/car is not in gear so there's no tendency of the car to surge forward with the engine speed.