So my 500 dollar Monte Carlo has had a misfire since I’ve owned it and I’m trying to figure out the issue and I’m honestly tired of it
I’m getting the infamous p0300 code I’m also getting a p0171 so i have the idea that they relate to each other it starts missing under load and not at idle I suspected a fuel filter I have one and it could be and egr valve but I’m not sure it’s not my firing order it’s good and plugs and wires were done a couple months ago and no signs of burns and such so I’m kind of lost any ideas?

Here’s all the codes it’s pulling hope this helps

 

Have you had the oxygen sensor replaced?

Oxygen sensor and getting the ICM tested could be good places to start.

 

Do you have a scan tool to read the sensor outputs?

 

no unfortunately...

 

both o2 sensors are shot because of the previous owner and the maf is bad found out yesterday any thoughts?

 

Your oxygen sensor controls your fueling when the car is up to operating temperature and in closed loop, if it's bad that is mostly the cause of these issues.

 

Noted so I did the test with all three maf’s Where you unplug them when your car is running and it stalls the sensor is good so that didn’t happen so I guess the maf is bad as well so new Maf as well and then o2 sensors and then an emulator because cat has been deleted and then a fuel filter and this should help cross fingers what do you think chib?

 

Well the "unplugging the MAF" isnt a fail safe way to test. You can buy a bluetooth scanner for very cheap and run one of the many apps off of a phone. I use torque for all my info.

You either need to get some info for the guys here or do like you plan and just start throwing parts at it which isnt really recommended.

As for the emulator, youre better off buying a PCM with the code removed. Idk, I never liked the idea of giving the car false info.

 

That test is more for when your car is stalling with the MAF hooked up. If your car stops stalling when you unplug the MAF (which makes the car run in a speed density mode) then the MAF is bad because it's giving bad data. The car shouldn't stall by unplugging the MAF. It's if your MAF is making it stall, you have the best backwards

 

gotcha so maf has a chance to be good cool not really trying to throw parts at this car but I wasn’t entirely sure what was causing the problem but I really need to fix this but from the history of the car I’m pretty sure you’re right as the previous owner thought it would be a good idea to cut off the exhaust and fouled the o2 because he tried to cut the cat too but didn’t finish and created a leak and the car lost power and it started missing and it fouled the cat and clogged it so I deleted the car since in my situation it was cheaper and where I live we don’t do emissions so I hope this new information can lead to some answers I have a fuel filter I’ve been meaning to put on so I will do that I’ll clean the maf since I’m running to the store and start there I’ll still need advice so thanks for the help so far y’all I’m still new to cars