Do you use the paramaterized-plugin in addition of the EnvInject plugin?
Could you attach your jobs configurations files (config.xml)?
Thanks

I can't post my actual jobs due to security and proprietary information reasons, but I created the scenario listed above and included it in the zip.

To the best of my knowledge (I didn't build this Jenkins server from the ground up, so I'm still learning what's an out-of-the-box built-in feature and what's a plugin), I do use parameters when creating the job (built-in?), but I do not use the Parameterized Trigger Plugin.

Check JENKINS-14739.zip for the configs, and if you run them, take note of the differences in the Injected Environment Variables for each.

config.xml files for the scenario in the description.

Your example is quite difficult for me.
Do you use environment variables for selecting your nodes?
Is it possible to provide a more simple scenario?

Any update?

Is it possible to help me to provide a simpler example?

I'm afraid I can't solve this issue.
Please help me by providing more information or further investigation?

This looks to me like it works as intended. The parameterized trigger only passes actual build parameters, not all variables defined as environment variables.

In many of my builds, I have a few parameters at most, and often dozens of environment variables to configure generic build scripts to the specific job (like paths to certain programs in specific versions). Please also note that many other environment variables exist by default, or are defined and redefined in the global Jenkins configuration and slave configuration. And passing PATH would quickly wreck havoc on downstream builds running on different machines.

An easy workaround for this issue also exists: Just add a "predefined parameters" element from the parameterized build trigger plugin, and enter PARAM_SLAVE=$PARAM_SLAVE to override the default value of the slave. Skip the "current build parameters" entirely, it's simply not what you want.