22re Idle surge with brake pressure

[aroising]

I'm sure someone has written an article about this somewhere but I figured I would ask you all wise Mud members. I've picked up a red headed step child to add to my Land Cruiser herd. Its a 93 Toyota Pickup. I got it with a blown motor and completed a swap last weekend. Everything went together fine, but I'm experiencing an odd issue. When the brake is applied, the idle drops from around 1500 to 600-700 and sounds like shes about to stall. Take foot off, and right back to normal idle. I disconnected the TPS sensor and the truck idles high but the brake has no impact on idle. I've checked the vacuum lines and from the booster everything appears fine. Any advice? Bad TPS sensor? Thanks for your help!

 

[2ndGenToyotaFan]

If you hold the brake on does it idle down and back up, and down again etc...? If so you may need to turn your idle speed down. If it just drops and stays down then I don't know... Check the trouble codes. There's a link in the FAQ thread under Engine Electrical...

Welcome to the dark side....

 

[aroising]

The idle goes up and then back down.

 

[2ndGenToyotaFan]

Hmmm but just once?

 

[aroising]

no it will continue to cycle until I release the brake pressure.

 

[Chop Shop]

Brake Booster is bad.

Unplug the large vacuum hose from it and plug the end of the hose. then depress the pedal and check for surging again.

I just replaced one doing the same thing last week. Pretty common when they have high miles and have sit for along time for some reason or another.