I've finally weeded my idle problem down to pressing my brakes.. My idle is perfect at all times and temperature.. The idle dips to 500 and then back up to 1000 rpms when I press the brakes.. Is it possible the brake booster is going bad? The brakes work fine and I don't feel any sponginess.. There isn't any air in the lines since a couple months ago I did a brake job including all new fluid, brakes, rebuild of drums.. Maybe I should check the hoses and look for blockage? My FSM isn't revealing any symptoms and diagnosis for this.. Thx all....

 

Check this out could be your problem
http://www.geocities.com/toyotashawn/bizzareidle.html

 

Where do you live? I just experinced the same thing. I live in CO Springs, CO. I was told that it is an idle speed issue. Your idle speed might be set to high.

 

Im in SoCal.. Im going to try the idle screw first.. thx for the site.. excellent info.. when i start my runner the idle is great and its around 750.. when it gets warmed up or I have driven it the idle stays around 1000-1100.. Maybe the throttle is sticking a bit causing the idle to stay higher and I can see where the injectors are kicking in with the brakes.. will try a few things tonight..

Thx..

 

Ok, first off I'm just guessing out of my ass here.

BUT there are certain little vacuum devices (VCV I think is one of them) that automatically bumps up the idle when using certain things (AC, for example, has one of these VCV devices). When the motor begins losing vacuum pressure or RPMs, it attempts to bump the idle up.

So, perhaps there are one of these somewhere on the booster or along the line to the back of the intake manifold.

 

Cold idle should be around 1200-1500 RPMs in the morning, so it sounds like your air valve needs a little attention.

Hot idle should be anywhere from 750-900 RPMs, but anything over 950 RPM's and the computer goes into "deceleration fuel cut" mode with the brakes applied and that's when the varying idle starts to occur. Adjust your idle for 900 RPM's and below.

 

There's two things that come to mind:
1. decel fuel cut
2. leaky brake booster

definately check for fuel-cut due to high idle.

try disconnecting your brake booster vacuum hose (and plugging it) and see if your booster is leaking. with the booster disconnected you won't have much braking power so don't drive it. Just plug the big vacuum hose, and then test to see if your idle hunting is still there.

 

Thx everyone for your input.. i wil try these tips.. I've gotten distracted from the idle issue, because i thought all of my oil leaks were fixed, but i discovered a leak where the timing cover meets the head gasket on the exhaust side.. i removed the power steering and put a little RTV to see if I can direct the oil leak.. I'm afraid it could be the head gasket, because i just did the timing chain and all of the front seals (oil pump, water pump, front oil seal and timing cover).. pondering a new LCEngineering long block or a rebuilt long block instead of doing a new head gasket.. I want a DD in addition to my weekend rockcrawler..

 

The leak may be form the power steering bolts themselves. I believe I read somewhere here that the power steering bolt holes are tapped into an oil gallery and oil will shoot out of the holes with no bolt(s) in place.

 

That would explain why my power steering pump bracket is the greasiest part of the motor.

 

i'll take a look tonight.. thx for the reply's