I have spent days scouring the Internet and have found no help. If someone could point me in the right direction I'd appreciate it. I have a 98 blazer 4x4 with the 4.3 vortec in it with 150k miles. It was recently given to me and my fiancé. I was driving the car and when I accelerated from a stop sign the car died. I went and got the codes ran and they are as follows... P0102 P0122 P0147 P0171 P0174 P0405 P0452 and p0500. I opened the air filter box to find no air filter. I cleaned the maf sensor and installed an air filter and it ran a little better but as soon as you press the gas hard it dies. If you baby the accelerator you can drive it around and get up to regular road speeds it just takes a little longer. My neighbor looked at it and thought it was the tps sensor because it dips below idle before returning to idle so I changed it and cleared the ecu. Did not make a difference and code still shows. I thought it might be a fuel issue but when I unplug the map sensor the car runs great with enough power to spin the tires but it runs really rich. I can smell the gas on my hand after cupping the tailpipe. Any help would be appreciated. If I forgot to include something or posted wrong I appoligize. I have never used a forum before.

 

P0102 - Mass Air Flow Sensor Circuit Low Frequency
P0122 - Throttle Position Sensor Circuit Low Voltage
P0147 - HO2S Heater Circuit Bank 1 Sensor 3
P0171 - Fuel Trim System Lean Bank 1
P0174 - Fuel Trim System Lean Bank 2
P0405 - Exhaust Gas Recirculation Sensor A Circuit Low
P0452 - Evaporative Emission Control System Pressure Sensor Low Input
P0500 - Vehicle Speed Sensor

The EGR valve, throttle position sensor, and the evap pressure sensor all utilize the 5V reference from the PCM. If one of those sensors is shorting out, it could cause insufficient voltage on the circuit affecting all of them.

 

I read somewhere about that being a possibility but couldn't figure out what was on what circuit. I'm not a mechanic by any means but I usually work on my own cars. I have never attempted to to find a short in the electrical system though. Is this something I can trace with a multimeter? Why does the car run better with the map sensor unplugged? Is the car going into limp mode? Why if I unplug the maf sensor does it not do the same thing? With the map plugged in and the maf unplugged the car won't start. The map sensor being unplugged is the only thing that triggers the car to run better. I appreciate your quick response.

 

You just likely fingered your problem. The MAP sensor is likely dragging down the reference voltage.
Measure for 5v between Gray and black with and without it plugged in

 

I'll do that first thing in the morning. So is it a defect in the map sensor itself that's dragging down the reference voltage or is it the fact that it's plugged in, completing a bad circuit that drags the reference voltage down. Basically is it the sensor or the cicuit thats bad? Will this test pinpoint that? I don't fully understand electricity and would greatly appreciate any clarification in this issue.

 

For a guy that doesnt understand electricity you did a pretty good job of describing the possibilities.
If plugging in the MAP causes 5v to drop:
1. poor connection at splice or gnd point
2. defect in source regulator - that would be the PCM, so you hope it isnt that.
3. Bad MAP internal circuit
Sometimes you do have to make assumptions.

 

I know this is really old but I recently swapped a tranny out on a 2000 Blazer 4x4 and immediately got P0122,P0405,P0452 when I started it for the first time after the swap. I wonder if I missed reconnecting a ground wire that would affect them all or something under ther. Did you have any luck figuring out what your problem was? Cause for all 3 of these to immediately go bad seems kinda weird to me.