1990 k1500 map sensor/ throttle position sensor error

[mdawg32892]

Hey y’all I’m having a problem with my truck and I’m just shaking my head at this point. I’ve got a 1990 K1500 Silverado 5.7 tbi extended cab 4x4. I’m getting a service engine soon light that gives me a code 12,22,32,33 from what I understand that’s the throttle position sensor error (signal low), code 32 can be one of 3 things baro sensor circuit error/ egr circuit error/ map sensor signal open. I believe it’s the map sensor. Then finally 33 map sensor circuit error (signal high indicating low vacuum) I’ve replaced the throttle position sensor, throttle position sensor connector, map sensor (x2), map sensor vacuum hose, map sensor connector, egr valve/ gasket, and the idle air control valve. Sometimes when starting up it stutters and the check engine light comes on then it goes away and clears up. While driving it will be driving fine no issues at all and then it loses all acceleration just goes to an idle and when I pump the petal it will try and rev up but stop and almost die from not getting enough fuel and getting too much air. Over my head ‍ I’m assuming it has something to do with a short or a bad ground somewhere I guess it must be electrical just looking for someone with more experience than me or someone that’s had the same experience. I appreciate any help y’all might be able to give.

 

[Schurkey]

1. What is the fuel pressure? HOW do you know it's getting "not enough fuel and too much air"?
2. Connect a scan tool, look at the data stream. Verify your sensors and wire harnesses.
3. How old are the usual "tune-up" parts--Cap, rotor, plug wires, spark plugs, fuel filter, air filter, PCV service, etc? How old is the O2 sensor? How plugged is the catalyst? When was the last time the throttle body was cleaned, including the IAC air passage?
4. Download a service manual for THAT VEHICLE from links posted on this website, find out the REAL meaning of those codes--and the diagnostic procedure for fixing them.
5. "Code 12" is normal. Forget it exists. That leaves 22, 32, 33.

 

[Erik the Awful]

When your truck acts up, are both injectors firing? Both injector connectors should always have power with the key on. The ground is provided by the ECM. I have yet to see an early GMT400 that didn't have crunchy injector connectors and wiring, and replacements with nice length pigtails are fairly cheap.