P0101 Mass Air Flow
 

2002 Blazer LS, 4WD, 4.3L engine, 144K miles. Bought this in an estate sale. Ran really rough, but I limped a half a block back to my yard. The first error codes were: P0101, P0155, P0300. After cancelling and restarting a few times, P0101 was the only recurring one. It will start and run ruff until I increase the RPM to 2000 and hold, where it runs smooth for a few seconds. It will only run about 15 seconds and start choking down and finally die after about another 10 seconds. The error code is still P0101, Mass Air Flow. I replaced the Mass Air Flow Sensor and its associated Temp Sensor. No change. It acted like it might be fuel starved, but, it checks 60psi...... I need help for the next step, please.

I might add: It won't restart at all unless I let it set for awhile. I didn't measure the time interval, maybe an hour. I use an Actron CP9580A tool to read and reset the error codes. It offered no other info except that it cannot "Link" with the Transfer Case, which is another problem I am working on (perhaps the Transfer Case Module).

I dont know what to do in this case sorry man best of luck, there is another thread i think with this issue do some reaseasrch and ull figure it out.

Latest development!! I saw somewhere that the catalytic converter might be the problem. So, I removed the upstream Oxygen sensor and left it hanging, still hooked up. The crazy Blazer started right up and didn't offer to choke down and die like before. It did show a misfire on cyl #4, so it was a little rough at idle. I have new plugs and hopefully it is not more serious than that. BUT...the question now is: does the catalytic converter need to be replaced or the Oxygen sensor, or both. There is no error code for either. Progress, but not there yet. Thanks for any help!!

Latest development!! I saw somewhere that the catalytic converter might be the problem. So, I removed the upstream Oxygen sensor and left it hanging, still hooked up. The crazy Blazer started right up and didn't offer to choke down and die like before. It did show a misfire on cyl #4, so it was a little rough at idle. I have new plugs and hopefully it is not more serious than that. BUT...the question now is: does the catalytic converter need to be replaced or the Oxygen sensor, or both. There is no error code for either. Progress, but not there yet. Thanks for any help!!

Some progress
 

Latest development!! I saw somewhere that the catalytic converter might be the problem. So, I removed the upstream Oxygen sensor and left it hanging, still hooked up. The crazy Blazer started right up and didn't offer to choke down and die like before. It did show a misfire on cyl #4, so it was a little rough at idle. I have new plugs and hopefully it is not more serious than that. BUT...the question now is: does the catalytic converter need to be replaced or the Oxygen sensor, or both. There is no error code for either. Progress, but not there yet. Thanks for any help!!

Latest development
 

I saw somewhere that the catalytic converter might be the problem. So, I removed the upstream Oxygen sensor and left it hanging, still hooked up. The crazy Blazer started right up and didn't offer to choke down and die like before. It did show a misfire on cyl #4, so it was a little rough at idle. I have new plugs and hopefully it is not more serious than that. BUT...the question now is: does the catalytic converter need to be replaced or the Oxygen sensor, or both. There is no error code for either.


Further news: #4 cyl has spark..........but only 80psi compression. Still throws an engine misfire at #4. Next plan is to pull the head from the right side and check the valves. Hopefully it is a valve leak instead of broken piston rings.


Progress, but not there yet. Thanks for any help!!