Have a 04 chevy trailblazer changed the map sensor due to code, it come back got it changed out again and it still wants to throw same code, not alot but seen more after when tring to use defrost or pushing recerculate button is pushed in motor up and down then shuts off.

when you shorted the sensing wires together you have probably destroyed the map sensor. the car will not start, as it needs the barometric and manifold pressure. look in your owners manual for the fuses and check, You can google 20004 Chevy blazer fuse box location and diagrams. Why did you change the map sensor, did you have a failure code indicating a problem? quit throwing parts and money at it.



Do It Yourself and DIY Auto Repair by ChiltonDIY

https://manuals.co/workshop/chevrolet/blazer/2000-chevrolet-blazer-owners-manual/5525

Those cars are notorious for engine problems unfortunately. The exhaust valves tend to warp from heat after around 200k miles. Therefore throwing the O2 codes. Best outcome and cost effective thing I can recommend is replacing the engine with a new or low mileage engine.

Your checking for codes & throwing parts at it

Your NOT diagnosing anything like the cylinder
misfires, because you don't have OBD2 System
knowledge or the proper professional tools to work
on it, or Chevy Trailblazer Powertrain experience

Best left to a repair shop

Your sensor could not be installed properly, you could have a vacuum leak, bad map sensor, or even a Mass air flow sensor problem. Isn't technology great! make sure the TPS sensor is seated properly. check for vac leaks in your hoses under the hood. Using small amounts of ether (starting fluid) and spraying it on vacuum hoses can help you find a vacuum leak. if there's a leak, your idle will increase due to it burning the ether. Not super safe but it's worked for me. try changing the other sensors & I hope this helps ya.

have it checked for cam shaft sensor

CODE B0055 IS A OEM CODE HAVE UR DISTRIBUTOR AND WIRES LOOKED AT.
CODE P0172 / BAD OXYGEN SENSOR -FUEL LEAK or BEND LINE -DIRTY INJECTORS or( dirty oily air sensor )chk them all
CODE P0106 BAD MAP SENSOR OR A HOLE IN UR (AIR INTAKE) BACK TO THAT AGAIN

did you replace only one spark plug? that can cause issues because of differences in resistances between cylinders. also, did the map code stay off after replacing
?

I would be suspect of the throttle position sensor, but have the codes read, WRITE THEM DOWN (if there are any), and report back here. TPS's failures will sometimes throw a code but does not require a CEL when they do.

change thermostat

If you have bearing problems MAP sensor codes are the least of your worries. Check on the cost of getting a new engine. I hope this is not the problem. Good luck Moe