'92 4Runner, V6

Within the past few months my brakes seem like they have lost some of their power. Pads are perfectly fine, fluid is within a decent age and nothing else is wrong that i can tell.

The pedal itself seems to change it's sensitivity depending on engine conditions...i will explain:

(1) During normal in town driving, it's 'satisfactory'. I have to push the pedal down a 'normal' amount and i get decent braking power.

(2) If i've been crusing down the highway for a decent period of time, my brakes feel very weak when entering an offramp. I have to push the pedal further than normal to get any power and i have to use more leg strength on it for adequate braking power.

(3) The brakes are BEST after i have romped on the engine. If i gas it, and hold it for a few seconds (say 4,000rpm for 3-5 seconds), my brakes are incredible. I barely have to touch the pedal for the brakes to grab and i feel like i could lay rubber with all four wheels with no problem. This is how it used to be.

Now, i have adjusted teh pedal so that it has very little slack in it to account for the fact that MOST OF THE TIME, it feels pretty mushy....that's why #3 is probably so sensitive and i would probably back it off slightly if i got this problem fixed.

This points to a vacuum problem with the brake booster OR the check valve that is placed in the pipe before it. I have taken the check valve out and cleaned it (just sprayed w/ WD40 to loosen any grime) but it didn't help. I don't see how the engine state could affect braking performance unless it were one of these two parts.

Does anyone else have any suggestions for this? Anyone seen this before?

Thanks for any help.

J.

 

el bumpo.

 

I don't know if it helps but yesterday I was working on my mustang (first time i started it since i got my pu). But a vaccume hose poped off of one of the connecters. It was ideling really bad and whenever i would hit the brakes they took quite a bit of power to stop. Once I figured out it was a vaccume hose and hooked it back up they worked great. It was a vaccume hose on my mustang but 4cyl ford engines suck. well imo all american cars do.