2006 hhr p0036 & p0300
Administrator
Joined: 10-13-2011
Posts: 39,998
From: Welland,Ont Canada
Causes and solutions, for Oldblue’s P0420, it was the catalytic converter
https://www.obd-codes.com/p0420
https://www.obd-codes.com/p0420
Thread Starter
Member
Joined: 08-07-2015
Posts: 61
From: US
random misfire
I've been troubleshooting a random misfire for 2 months and it's driving me crazy.
Fuel pump went bad & was replaced (FYI, likely unrelated).
Vehicle began acting up so battery was tested/replaced and MAF cleaned (still idled rough).
Code thrown for CAT/O2, replaced all O2 sensors, cat, & plugs...still idled rough.
TODAY;
Re-cleaned MAF, added fuel system cleaner, and confirmed plugs were still torqued to spec.
Turned engine over, idled fine until warm, began shuddering randomly once warm (still idled rough).
I heard what may be valve chatter while the engine was warming up and after it hit operating temperature.
Took a 5-minute test drive on interstate just now to get fuel cleaner into system and the idle is MARKEDLY MORE STABLE after the test drive.
I'm debating running the post-MAF fogging injector cleaner and/or add some SeaFoam to the oil and/or adding some ISO HEET with fuel injector cleaner in case there was water in the lines.
I've not used ISO HEET or anything else yet as I'm experiencing the first identifiable success in a month+ and don't want too many variables mucking things up.
Based on the information presented, what are y'all thoughts?
Fuel pump went bad & was replaced (FYI, likely unrelated).
Vehicle began acting up so battery was tested/replaced and MAF cleaned (still idled rough).
Code thrown for CAT/O2, replaced all O2 sensors, cat, & plugs...still idled rough.
TODAY;
Re-cleaned MAF, added fuel system cleaner, and confirmed plugs were still torqued to spec.
Turned engine over, idled fine until warm, began shuddering randomly once warm (still idled rough).
I heard what may be valve chatter while the engine was warming up and after it hit operating temperature.
Took a 5-minute test drive on interstate just now to get fuel cleaner into system and the idle is MARKEDLY MORE STABLE after the test drive.
I'm debating running the post-MAF fogging injector cleaner and/or add some SeaFoam to the oil and/or adding some ISO HEET with fuel injector cleaner in case there was water in the lines.
I've not used ISO HEET or anything else yet as I'm experiencing the first identifiable success in a month+ and don't want too many variables mucking things up.
Based on the information presented, what are y'all thoughts?
Administrator
Joined: 10-13-2011
Posts: 39,998
From: Welland,Ont Canada
Replace the thermostat and the Dexcool, use only the AC Delco 131-158 180 degrees thermostat.
You didn’t mention cleaning the throttle body , clean it with CRC throttle body spray cleaner, DO NOT try and open the throttle plate manually by hand, the little plastic nylon gears will strip very easily, I just unbolt the four hold bolts and lift up the throttle body , then squirt the cleaner on the manifold side of the plate, let it air dry a minute and bolt it back in place.
You didn’t mention cleaning the throttle body , clean it with CRC throttle body spray cleaner, DO NOT try and open the throttle plate manually by hand, the little plastic nylon gears will strip very easily, I just unbolt the four hold bolts and lift up the throttle body , then squirt the cleaner on the manifold side of the plate, let it air dry a minute and bolt it back in place.
Thread Starter
Member
Joined: 08-07-2015
Posts: 61
From: US
B/C the cat was trashed, breaking apart, and pieces damaged the downstream O2 sensor.
B/C of the damage & related codes outlined in another thread.
2006 only has 1 cat.
Thread Starter
Member
Joined: 08-07-2015
Posts: 61
From: US
Replace the thermostat and the Dexcool, use only the AC Delco 131-158 180 degrees thermostat.
You didn’t mention cleaning the throttle body , clean it with CRC throttle body spray cleaner, DO NOT try and open the throttle plate manually by hand, the little plastic nylon gears will strip very easily, I just unbolt the four hold bolts and lift up the throttle body , then squirt the cleaner on the manifold side of the plate, let it air dry a minute and bolt it back in place.
You didn’t mention cleaning the throttle body , clean it with CRC throttle body spray cleaner, DO NOT try and open the throttle plate manually by hand, the little plastic nylon gears will strip very easily, I just unbolt the four hold bolts and lift up the throttle body , then squirt the cleaner on the manifold side of the plate, let it air dry a minute and bolt it back in place.
I've yet to clean the TB again (removed & cleaned about 10K miles ago) b/c the vehicle is too dirty. I took my son hunting and the mud was worse than expected. We made it out but it nearly cost me a bumper. I'll clean the TB after I've cleaned the engine bay with a pressure washer. The garden hose wasn't sufficient.
Thread Starter
Member
Joined: 08-07-2015
Posts: 61
From: US
DonBrew, here's a link to the other thread about the cat and O2. The engine was acting up right before the fun referenced in the below post.
https://www.chevyhhr.net/forums/prob...6-p0300-62642/
https://www.chevyhhr.net/forums/prob...6-p0300-62642/
