Chevy Silverado and GMC Sierra Forum banner

1998 Sierra 4.3 won't start

6K views 4 replies 3 participants last post by  esquivelemb 
#1 ·
Hello everyone,
New to the site and proud owner of a '98 Sierra,
My truck won't start and my obd2 reader gives me code po108 as an only code, is it posible that the MAP sensor is not letting my truck start ?
Any comment appreciated.
 
#2 ·
In unison with the Manifold Absolute Pressure (MAP) sensor, the engine control module (ECM) regulates the flow of fuel and the ignition timing.
The MAP sensor which is metric pressure enables the ECM to make necessary adjustments for differing altitudes.
The output voltage of the MAP sensor changes with the change in the manifold pressure.
The intake manifold pressure created due to engine load (intake manifold vacuum) and the rpm changes is measured by the MAP sensor and transformed into voltage outputs.
The ECM notes the manifold pressure by keeping a vigil on the MAP sensor output voltage.
The MAP sensor directly receives a 5 volt-reference voltage sent to it by the ECM.
At idle, about 1.0 to 1.5 volts indicates a low-pressure (low voltage) output voltage.
At wide open throttle (WOT) about 4.5 to 4.8 volts indicates higher pressure (high voltage) output voltage. check to see if the map sensor is pluged in . and check connector if bad 9 times out of 10 just replace it
 
#4 ·
The MAP sensor directly receives a 5 volt-reference voltage sent to it by the ECM.
At idle, about 1.0 to 1.5 volts indicates a low-pressure (low voltage) output voltage.
At wide open throttle (WOT) about 4.5 to 4.8 volts indicates higher pressure (high voltage) output voltage. the map sensorcould be getting to much or to little voltage
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top