I'm a little upset right now, so if I write something stupid I apologize in advance...
My car has been throwing a code 34. It's an '84 Trans Am LG4. The car ran a little rough at idle until this evening when it wouldn't stay running. It would start fine, but only a few seconds later would die. I inspected all the electrical connections to the MAP sensor and traced them back to the ECM. I didn't find any real loose or corroded connections. I replaced the MAP sensor. I took off the air filter housing and looked around. I noticed that two vacuum hoses were off. There was one at the back of the carb which I easily found where it was supposed to go. With the other hose, I can simply NOT FIND where it is supposed to go! It's located in the front of the engine, and it tees off from another line. The original line looks to be a very thin hard plastic that has pieces replaced with soft rubber, kind of like the hard line broke, so someone put rubber over the crack. I am really pissed and frustrated to say the least, and I don't know what to look for next. Is this vacuum line my problem or WTF? Can anyone point me in the right direction? Does anyone have a vacuum line diagram?

 

Well the vacuum hose in the back of the carb goes straight to the MAP sensor, there's your code 34. For future reference, a normal MAP sensor will read 4.6-4.8 volts at 0", 3.75 volts at 5" (using a hand-held vacuum pump), and 1.1 volts at 20".

 

Thanks very much for that diagram! I noticed that one of the lines on the canister control valve was bent pretty badly, and might have caused a leak. That may be why the car doesn't want to run. Theoretically, could I replace all the vacuum lines and it would take care of all leaks? When the car throws a code 34, it's usually the vacuum sensor or a line leak right? I wish I could just tear all of this stuff out!

 

In addition to changing all the vacuum lines, check the rubber boots that fit onto the TVS's and the EGR solenoid. I think Pep Boys sells some silicon vacuum hose, you might want to look into that as a replacement (I don't know anybody that's used it before though, so I'm not necessarily recommending that you get it). Also, you can use a spray bottle of water or some carb cleaner to find specific leaks, the engine will change if you spray it over a leak.

A code 34 means that the engine has been running for several minutes at idle speed and either the computer does not detect the MAP sensor via the 5V check voltage, or the vacuum reading for idle is lower than it thinks it should be.

 

Get a load of this one... I pulled the vacuum hoses off the TVS next to the thermostat housing, and it was wet! It let a small amount of moisture out and it smells like gasoline! Since one of the lines comes directly from the charcoal canister, is this telling me the engine was running obnoxiously rich because of a code 34, and also rich because of a bad oxygen sensor?

 

I don't think that is very unusual. Mine was the same way when I changed my intake a week ago. I've heard that it can be caused by the carburetor flooding, so probably at least once since the last time that hose was pulled and now your carburetor flooded. Not sure if it's anything to really worry about, unless it does it often.