Toyota Nation Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter · #1 ·
When my 89 toyota pickup is idling it revs by itself up and down sometimes. It doesn't do it all the time. Although it always revs up and down when you push on the brake. We changed the throttle position sensor and ajusted it to the right spot. We also were playing with the throttle screw. It is screwed all the way in. But the idle never stays the same. The idle will sometimes be at 1000 and after that its all in between 1000 and 2000 RPMs. When the truck was reving up and down with the brake on we pulled the vacuum hose that goes to the brake. It still reved up and down. So we thought it might be electrical or the computer. So if anyone can help, send a reply. thanks
 

·
Toyota Fanboy
Joined
·
4,486 Posts
You have a vacuum leak on the brake booster.
 

·
Banned
Joined
·
2,353 Posts
if your truck idle above 1200 rpm when at operating temp and the brake applied it will do this. you need to lower the idle speed to within spec (750-850) rpm.. its slow and tractor like at idle. check the idle up vsv actuator on the throttle body, or the idle screw its self on top of the throttle body. i gaurantee if you lower your idle after its warmed up and goes to closed loop it will stop bogging and it will stay low. every time you hit the brake above 1200 or more rpm the truck will cut fuel to the engine to save gas and reduce emissions. it drops and creeps back up untill it cuts again. so yes it is electrical and you wont fix it until your idle is within spec. you may have a vacuum leak somewhere else causing the racing idle, more than likely youll tighten the idle screw and it will drop. the idle screw is in the pic here,

http://members.cox.net/jzulauf/idle.JPG

tighten the green screw in the pic and your idle will drop. or it should. if not you have vacuum/ timing or fuel problems.
 

·
Registered
Joined
·
406 Posts
do what subliminal said, ill guarantee thats your prob. I had the same problem and is now fixed by doing this trick.

-Adam
 

·
Nimrod152
91 Ext 4x4
Joined
·
43 Posts
I love you Toyota Nation

I had a tune up last week, and I had the same problem, Idle way up than way down when my foot is on the break. I took it to the Mechanic that did the tune up and he told me it was the master break booster... I unhooked the vacume line and it fixed the idle when I would push on the break, but left me with no breaks. After reading this thread I went out at 3am and adjusted my timing screw, Fixed the problem, I had already bought a new Master Break booster to be installed next weekend, You just saved me $300 Thanks so much.
 

·
Registered
Joined
·
19 Posts
I'm having this same problem with my 22re. It only happens when the A/C is on and I press the brake. No problem any other time. My truck also Idle's around 1200 rpm. Should I adjust?
 
1 - 6 of 6 Posts
Top