Brakes applied=up and down idle
#1
Registered User
Thread Starter
Brakes applied=up and down idle
Has anyone ever figured this one out? When I hit the brakes (only when I hit the brakes my idle goes up and down) But doesnt do it when the engine is cold. Only when its at operating temps or warm. My idle screw is set good. My truck has always done this..
Thanks,
Mario
Thanks,
Mario
#2
Registered User
My '94 did this for a little while. There is a valve that bumps the idle speed up when it's cold. After the engine heats up the valve should shut itself off and let the idle return to normal. Mine was clogged and not operating properly.
There is a separate system that uses the a vacuumn line and the brake booster to cut fuel to the injectors when you step on the brake, if the engine is above a certain RPM.
In my truck, the two systems were operating against each other, and if I was off the brake it would idle reall high, but on the brake it would surge up and down.
Search this forum and you'll find a bunch of other threads about surging idle.
There is a separate system that uses the a vacuumn line and the brake booster to cut fuel to the injectors when you step on the brake, if the engine is above a certain RPM.
In my truck, the two systems were operating against each other, and if I was off the brake it would idle reall high, but on the brake it would surge up and down.
Search this forum and you'll find a bunch of other threads about surging idle.
#5
Originally Posted by ttr125mar
Has anyone ever figured this one out? When I hit the brakes (only when I hit the brakes my idle goes up and down) But doesnt do it when the engine is cold. Only when its at operating temps or warm. My idle screw is set good. My truck has always done this..
Thanks,
Mario
Thanks,
Mario
My 88 Toyota 4WD Pickup has recently started having the identical symptom your describing. I'm the trucks only owner, have you gotten a response on your problem.
I haven't had time to sort out the source of the problem or what might cause it.
Del
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#8
Registered User
These guys had this question so many times they made a sticky out of it... I haven't had a chance to try their recommendations yet but it sounds dead on.
http://www.toyotanation.com/forum/t113388.html
http://www.toyotanation.com/forum/t113388.html
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