Codes P0302, P0106 and P0107, rough idle when the A/C is on

FORDSMB454

MEMBER
2005 CHEVROLET TRAILBLAZER
4.2L
6 CYL
2WD
AUTOMATIC
120,000 MILES

My truck has a very rough idle when I turn on the A/C, as well it really has bad idle to the point the truck will stall. If I drive it's fine the moment I'm at a light I have to watch it otherwise it will stall. So I have to shut the A/C off before it does truck also has a p0302 code. I've replaced the coil pack for it and all of them twice nothing's changed. I've changed the spark plugs, nothing's changed. I've also changed the MAP sensor twice, and cleaned the throttle body, I have no idea what's wrong. The reduced engine power light came on when p0106 and p0107 came on. The p0302 code comes on when I fill up my tank with has then goes off when its 1/2 way full sometimes and there is a bad rattling noise on bottom of the truck. The transmission goes into gear perfectly, nothing wrong; no missing gears, nothing. Goes into gear fine, no hesitation. I have no idea where this rattle noise could be either. If you have any ideas on any of these please let me know. Thank you

1 Reply

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

Hi,

The idea that the misfire hasn't gone away has me a little concerned. I want you to try something. Take a rubber mallet and tap on the exhaust system to see if you can recreate the sound. If you do, see if it is coming from the catalytic converter.

Also, I need you to check if there is spark at the cylinder two spark plug. Here is a link that explains how it's done:

https://www.2carpros.com/articles/how-to-check-for-ignition-spark

It isn't uncommon for them to come apart internally and rattle. This can often lead to the internal components moving and reducing airflow. As a result, the vehicle will not run properly.

Take a look through this link and let me know if it seems to mirror anything you experience:

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

Also, if possible, record what it is doing and upload it for me to hear, and if you have a live data scan tool, let me know what the short-term fuel trims are and if you have checked for engine vacuum leaks and fuel pressure.

Take care. I'll watch for your reply.

Joe