Check engine light on, engine running rough

The ignition coil on the number five cylinder may have a bad connection or bad power or ground control causing a misfire . Sometimes the coil itself may be bad .

How To Fix P0300 random misfire codes in your car ...

? 2:56
https://www.youtube.com/watch?v=OyvdWeyDHf4
Feb 5, 2010 - Uploaded by Scotty Kilmer
Scotty Kilmer, mechanic for the last 46 years and counting, shows how to fix your car if the check engine light ...

P0300 - OBD-II Trouble Code - RepairPal

repairpal.com > Encyclopedia > OBD II Codes

OBD II Fault Code. OBD II P0300. Fault Code Definition. Random, Multiple MisfireDetected. Symptoms. Check Engine Light flashing; Rough running, hesitation ...

P0300 - Check Engine Light Diagnostic Trouble Code ...

https://www.engine-light-help.com/P0300-check-engine-light.html

The misfire detection monitor, a software strategy built into the computer, is designed to detect an engine misfire. The computer can also normally identify the ...

Random-Misfire Page

www.random-misfire.com/

Check Engine Light/Misfire Due to Intake Valve Locks ...

repairpal.com > Problems > Jeep > Liberty

Jeep Liberty Check Engine Light/Misfire Due to Intake Valve Locks/Valves. ...Misfire cyc 4 and random cyc misfires, changed coil packs and plugs... sounds as if rod ... Light came on again (misfire on cylinder 4) - switched coil from 4 to 2. Light ...

Jeep Liberty Questions - Cylinder Misfire code - CarGurus

www.cargurus.com > Questions > Jeep > Liberty

CarGurusMay 27, 2009 - #4 misfire new plugs and coil pack on #4 light came back on after 300 miles if ... How come it stopped misfiring for 2-3 months, and now is back? ... I have a 2005 Jeep Liberty 6 cylinder, engine light came on scaned the codes ...

Liberty Cylinder Misfire / Computer issue? - JeepForum.com

Lets start at the beginning. Did anyone check fuel pressure before and after replacing the pump ?
Has anyone checked the fuel pressure regulator and the injector spider ? The 4.3w engine uses a spider with one injector that supplies all 6 cylinders. And it runs at 65psi or more.

Go HERE to read about engine misfire diagnosis and repair.

the light is flashing from a misfire have it scanned and the codes will lead you to the bad cylinder

Rob, when the battery is disconnected for any reason a couple of things happen, and frankly it's a design error on the GMT360 platform (Envoy/Trailblazer). Your mechanic did not make an error here. Issue #2, your vent actuators blew out when the battery was re-connected back up, it happens, it's common. Issue # 1 is a little more complicated. The flashing light means misfire, is a seperate issue and a coincidence. Pull the codes out with a scanner and report back, may be bad coil pack, happens and is common. Idle problem and starting to die is an easy fix, betting it only happens when the AC or defrost is on. Disconnect fuse #10 and #28 under the hood. Remove the throttle body and clean it with a sensor safe spray like Seafoam. Drive it around for the computer to relearn the newly cleaned throttle body. Idle problem will be fixed.

If you've gotten a tank of contaminated fuel, I'd check on the condition of the injectors first.

Hello Frybird.

The codes you have are engine misfires.
Code 300 is random misfire (could be any cylinder).
Code 302 is cylinder #2 misfire and 303 cylinder 3 misfire.

Most common causes are ignition issues.
Spark plugs, ignition wires/boots and ignition coils.

Next would be fuel issues such as fuel injectors.
Next would be emission components such as EGR valves.
Then in a worst case condition would be engine wear parts (valves, camshafts etc.)

The place to begin is ignition as this is a common failure on most cars.

If you need further assistance regarding your question please ask me here in a comment.
Thank you for using FixYa.

KL