This is actually a second thread that I originally thought was a fuel pump issue but after reading replies and searching i dont think so.

The cars a 85 vette with no major mods or stored codes. The car was running fine one day, the next day i start her up in the morning and it sounds real rough and a real strong gas smell (lots of smoke). Being the handy man machanic that I am (I usually always find the problem) I tryed the disconnecting MAF trick and viola the car starts throws a code and runs decent. So I go buy the MAF and same thing (I reset ECM). Regardless of plugged or unplugged the car is real hard to start when cold. After warmed up the car (MAF unplugeed) runs decent. I read the relay is on top of the ECM. I've read that most sensors take a couple minutes for the ECM to use them. The car immediatly shows these symptoms when MAF plugged in. I guess my question is what sensors are used upon exact start up of the car. I'm trying to isolate the problem so I know what to expect from the mechanic. Any guesses . Another question in my head is when i'm unplugging the MAF i know i put the car in that limp home mode what sensors are not used in limp mode that arent used in closed or open loop.

 

OK, on a cold start up the ECM is looking at its internal timer, TPS and coolant temp sensor. It monitors the CTS, and when it reaches 156 ish (I belive that's the number) it will then look at the O2 sensor and see if it is warmed up and responding. If not it goes back to the timer and looks again some seconds later, until the O2 is responding like it should. Once it is satisfied withthe O2 it hits closed loop and uses all of its sensors. Also cold start up uses the cold start injector, but it is a system that is totally independant of the ECM.
When you unplug the MAF the ECM defaults to preprogrammed fueling tables based on TPS, not really limp home, more like an alternate fueling mode.

Since you are playing around with the MAF connector... have a look at the female pins on the harness end. Look carefully for any of them that might be spread open. If you find any, use a sharp pointed awl or like, and carefully close the pin. (had this problem on my 85 when it was new)
Next You need to check for 5V on the MAF power wire.
If you have a laptop and even rudimentary solidering skils, get Winaldl and make the cable for it. Hook up to the car and see what the Gms/sec the ECM is seeing from the MAF at closed loop idle (should be 7-12 roughly)
Post back with your findings.