89 S10 blazer- check engine light
 

Hi everyone,i have a 89 S10 blazer 4.3 with a problem that seems like a bad map sensor.it throws a code 34 but i dont know how to Fix it.code34 is low voltage on map sensor,the check engine light goes on while driving and then i stop the car and restart the engine and the check engine light goes off.i changed map,iac,plugs,cables,tbi.it idles ok but as soon as i put it in Drive after driving for afew minutes its start to stuter.any help!!!!!!!
greetings from the baja

1989 4,3 s10 blazer code 34
 

hi everyone greetings from the baja mex.i got a problem with my s10 blazer 4.3,i recently bought it and it ran fine then after a couple of weeks when i go to turn it on it would turn on for a few seconds while the rpms go up to bring the temp up,but as soon as the rpms went down it would start to shake and stutter and finaly go off.it would take me 3-4 times to get it to stay idle.went to a mechanic and his response was to change iac,map,spark plugs,spark plug wires,rebuild tbi,fuel pump,fuel filter,engine oil,oil filter.vacuum lines,air filter and after all that the truck performance got a little better.it would turn on and stay idle at the first crank but now the problem would start when it was placed in gear ,weather it was reverse or drive.it was ok for a few minutes while driving and then suddenly it would start to rattle klike a misfire.i would need to step on the gas pedal lightly .and after a few days the check engine goes on but only sometimes and other times the check engine light wont go on but the stuterring problem is still there,i bridged the adld to get code error it throws up code 34 which is low voltage on map sensor but i donot know how to tackle that problem,i ive in a remote town where there is no one specialised inin these fields any help would highly apreciated.
ps:i checked spark plugs and 3-4 come up wet with oil

Threads merged.

What comes to my mind is that the voltage delivered to the sensor itself is already low.
This can be caused by a multitude of issues with connectors and wiring.

Careful, as normally the voltage to the sensor is only 5V delivered by the ECU.
I would start by measuring the voltage at the connector to the sensor. Then following the wiring from the sensor all the way through the connectors to the ECU.
Inspect all the connectors, wires, clean the contacts/connectors and re-measure voltage at the sensor.

This may require a voltmeter and the ignition "ON".

One would need the correct service and diagnostic manual to do the proper test. Maybe somebody can post the diagnostics page.

Hello Sergio,

if you got a used rear bench available for me please let me know, I got the same as yours.
Thanks
Don