95 z28 info in sig ok runs good at first then it starts missing after 5 mins or so coming up with code for map sensor would that cause it to miss like that and if i shut it off for a lil it will be ok for like 5 mins again help plz thanks

 

check the plugs and wires. my car was misfiring cuz i got some liquid on a sparkplug but wiped it off with a papertowel and didnt misfire anymore.

 

Im going to put new in soon

 

What have you done about the code for the MAP sensor? Which code is it?

How old are the O2 sensors?

 

O2 not so good have new on way map I tried a old one but it made it worse... Will the map make it be like that and what not thanks

 

The O2 sensor will make it run like crap if its bad.

Mine did the same thing. Drove just fine for the first few min, then when the engine warmed up enough to go into closed loop it started to run like its only hitting on 3 cylinders.

Replaced the sensor and it runs perfect now.

 

The MAP sensor is used as a measure of engine load. It is one of the axes of the ignition timing map. It (along with rpm) is also the basis for defining the closed loop fuel correction cells. It is also used if the PCM needs to switch to speed-density.

 

My car won't go in to closed loop why is this

 

Three things have to happen:
-coolant temp exceeds ~140*F
-O2 sensors hot (>600*F) and generating a voltage
-PCM timer to closed loop times out (usually about 205 seconds)

How did you determine it's not in closed loop?

 

Datamaster

 

And does the closed loop flag bit not set to "1"?

 

Dont know what u mean all I know is up in the right side it has open and after 30 mins of run time it has not went to closed

 

In the upper right side of the standard DataMaster screen there is a box with binary bit indicators of various functions. One of them can be set to indicate "closed loop". "0" = open loop; "1" = closed loop. Then there's the top status bar that indicates a bright green "Closed Loop" on the 3rd box from the right, which I believe is the one you are referencing.

What is the coolant temp indicating when it's not in closed loop after 30 minutes? What is happening to the left and right O2 sensor volts when it's not in closed loop after 30 minutes? What cells is it operating in?

Might also not let it go into closed loop with the MAP code active, because it would prevent it from using the correct cells for learning and for fuel correction.

 

i just fixed that problem in my car two wire were cut and did a whole tune ups for the car also check that the cat is not clogged