I had a weird brake failure experience last weekend.

The background:
So, I'm still trying to track down a leak between the throttle body and block. I believe it's the culprit that is causing a lean condition with my URD set-up since I have the injectors at pretty high duty cycle and I'm still getting P0171. It progresses to a more frequent condition in the last few days where I can't go into boost without risking a lean condition.

Anyhoo, I've been driving the traffic like crazy trying to find parking for Austin City Limits Music Festival. So, I wouldn't be surprised if the brakes are hot. When I finally find parking, I noticed the brake pedal goes farther in with less resistance. I also noticed a loss in braking. To park the truck, I had to pump on the brake pedal.
After the show, I start the truck and the brakes work fine. No mushy pedal and the brakes stop just as it had before the failure.

It has been a few days and the brakes are still working fine. The brake fluid level is in the middle and I didn't see any leaks.

Now my idle hunts a bit. I also still have a frequent stumble in idle.

Maybe it's time to go back to pre-URD state to see what's wrong.
Any suggestions for things I should check in my brake system?

I don't want the brakes failing on me in a dire situation so i want to fix whatever the problem is immediately.

Thanks,
J

 

hows the vaccum boster any leaks ? brake lines soft? also any other mods done for the s/c ?

 

I'm not sure if this will help but got the same code (no s/c) and decided to change my A/F sensor; code still keeps coming. Take off the MAF and clean her up w/ electrical spray cleaner; code still keeps coming. After a few posts here, it's recommended I change the MAF. OK, might as well try; no code for the past week. I'm not sure how the s/c affects the MAF but maybe a new one can help.

 

You could have moisture in your brake fluid, especially if it's old. That'll lower the boiling point, which can cause the symptoms you described if the brakes get hot. Brake fluid should be replaced every 2 years, so if it's older flush it out and put some new stuff in there..

 

Sounds like the ticket...Check all your lines, look for leaks under pressure, and then change out the fluid.

 

I had the same thing happen, I had smoke pouring out of my new tundra brakes as I came down a really really long steep road. My rear shoes are shot from a axle seal leak so the fronts were over worked.

Well when the fronts got that hot the pedal got really mushy, after letting it cool down the pedal went back to what felt like normal. To be safe I re-bled and flushed all of the fluid out and have been fine ever since. Course I still need new rear shoes but that is another story.

 

Hrmm is there anything else you did? because i just bought a rebuilt OEM MAF yesterday and threw it in, cleared the code. drove around for about 15 miles. Bam, CEL back on, same code :cry:

This really sucks because now im stuck with the MAF, they wont allow returns on eletrical equiptment.

My next step is to change out my front O2 sensor. if this wont work i might just be stuck with a CEL code. Any other things that may cause this? And yes my 96 4R is S/C.

 

if no leaks found in brake system and pedal still low......brake master cyl.maybe leaking internally

 

no problems so far with the brakes when driving under sparse traffic conditions (less braking involved).
I think the fluid needs to changed out since it's old.

Anybody know if a dealership or toyota parts dealer offers discount to forum members?