I have a 1994 5.0 with auto trans. I have been have some rough running problems and things like that. I have I believe narrowed the problem down to a vacuum leak. While inspecting my truck I found a loose hose connected to the rear axle and then goes no where.



The hose is about 2 feet long and connects to nothing just flops around.

Where is the hose suppose to go as I could not find anywhere to connect it to. I know that the fitting it is in is the brake lines for the rear wheels but I do not know if it actually has anything to do with the rear brakes.

Also I am getting the infamous code #33 EGR not opening which I do believe is because of a vacuum leak. I am pretty sure that these two problems are connected.

 

That doesn't get vacuum and isn't causing any vacuum problems for you. That is the rear axle vent, it runs to the frame and then has a vent cap on it. The bolt that holds the brake hose tee has a hole through it to the inside of the axle to use for venting. It doesn't have anything to do with the brakes except to hold the hose on.

There is a vacuum hose diagram under the hood showing the routing of all vacuum lines except the brake booster which just goes from manifold vacuum to the booster. Your EGR may be stuck, you can try removing it and cleaning it. But first make sure the vacuum lines are good. Manifold vacuum runs to the EGR control solenoid and then to the EGR valve. Make sure the solenoid has vacuum in and check for vacuum out, but it will only have vacuum out when the computer tells it to.

 

There in lies the problem, apparently the truck had been in a wreck and there is no vacuum diagram. I have replaced the EGR as it was the original with 185k miles on it along with the EVP to make sure that was working right.

I do have a question about the code 33, if my truck starts misfiring enough will it loose vacuum and cause the EGR to close when it is supposed to be open?

 

I don't think that the misfiring will cause the EGR problem, but I suppose it is possible. I think the EGR control solenoid connects to the vacuum canister so it has a steady supply of vacuum, but I can't tell from mine because it's too dark to trace my lines and mines an '87. Your diagram should be on the air filter box but they do go missing sometimes when people add CAIs.

 

I have a 1998 f150 with a 4.2 and I also have a misfire and found the vent tube on the rear axle was loose. I reconnected the tube and now my check engine light is off and so far my truck hasn't misfired. Don't know if they are related or not.