Poor idle... Still chasing this goose.

[dylangumby]

Theres already a thread in here in regards to poor idle, but I started a new one because I have been chasing this problem for a long time and I'm looking for ideas before I go bankrupt or insane!

High idle works fine, the car will idle at 1500-2000rpm when you first start it depending on temperature.

After that, my idle drops to 650-750 ***JUST*** below normal.

If I turn my heater on, the idle drops to 500 and the car shakes. Headlights, same. If I engage the power windows the idle doesn't suffer too badly until the window is rolled up or down all the way and I continue to engage the switch. I'm assuming this is because the electric motor doesn't use its maximum potential power to roll the window up or down until its closed and pushing or pulling as hard as it can, the amperage that the motor is using spikes to maximum potential.

No single electrical usage makes the car idle at 500, but any of them combined will make it idle poorly and vibrate quite bad.

Feathering the gas just slightly when this is happening makes it go away.

I have replaced: Rotor, Cap, Wires, Plugs. New MAP Sensor, battery, and alternator. The water pump, timing belt, and all of the drive-belts are new.

ALL YOU TOYOTA GODS; I PRAY TO YOU!!

[90 GP]

Does your engine have a carburetor? ? If so check throttle positioner adjustment and vac lines feeding it. It's on left side of carb. If it's fuel injected only the base idle is adjustable and the computer adjusts it for any load.

[NZAE92]

have you started looking for vacuum leaks that could be one main source of your problems?

[dylangumby]

No Carb, its a 4AFE.

I have looked, I'm going to try the WD-40 spray test soon, I just learned about it today! I'll give that a try.

[Flashmn]

WD-40 sucks for finding anything, get some engine starter spray and use that to find air leaks.

What you havent replaced is the idle up solenoid or the O2 Sensor.

[dylangumby]

Good point, ether or alcohol would be a better option! I hope to do that this weekend. What am I listening for? A drop or rise in rpm, or just any change in engine sound?

http://www.toyodiy.com lists the part as an idle-up diaphragm, and when I peek under my hood it looks like there is two of them?? Bolted to the firewall at the top left side of the car. (Top Right if you're looking in the engine bay from the front)

At least its an easy part to replace, I'd trust myself to do it, I'm just hoping I don't have to buy two?

o2 Sensor is the one that bolts into the exhaust manifold, and "points at" the radiator?

[dylangumby]

So in the meantime I just had the idle turned up pretty high (like 1800) so that when I was using accessories it wouldn't dip below 700.

I just replaced the o2 sensor, and the idle was much more responsive, I turned the screw down an entire turn, and the car now idles around 1300 with no electrical accessories, and won't dip below 800 when everything is on.

Next is the two idle up solenoids! Still haven't shot alcohol at this thing, but I'm guessing its my Diff-Lock Solenoid (or hose to it) that has a leak, because its touchy and doesn't work on demand, it will engage at a random interval of driving.

I haven't pulled it out of the garage since replacing the o2, but the exhaust smelled much less tainted, and had barely and fuel smell to it at all once the engine warmed up. I'm hoping for a couple extra km per tank of gas! =)

[Rod K]

Hello!
I was just wondering if you had any success with your rough idle issue? I am still getting a similar problem, I hoped maybe someone found out an answer. I know a lot of threads seem to just drop off and disappear with no resolution ever given. So I'm trying to tie up lose ends and maybe find out an answer along the way? Thanks! Rod

[retiredat44]

as stated in many threads,,, there are procedures either in the manual, or online on website like Autozone that show who to make the adjustments to the fuel delivery, ignintion, idle and more... it isn't hard but fllow directions, and make sure you have a tach, asnd check for vacuum leaks,, and make sure all parts are in decent condition..

I am not trying to be a smart ass, but the directions in detail with step by step help are out there,,,

I wish you like as we all learn through asking and searching and trying..

[verlaryder]

Has the throttle plate and it's surrounding bore ever been scrubbed clean with a toothbrush and old rags soaked in throttle body cleaner?

[Lagos]

Good to also check ignition timing,mechanical timing, and do a compression test.