2021 P0300

2018 Views 14 Replies 6 Participants Last post by Philth, 10 mo ago

CDorocki

Discussion Starter · 11 mo ago

Hello all! Joining some of the forums outside of Facebook seeking some additional help. I'll provide a link to that post as well as it's a bit lengthy, I'll keep it short(er) here.

I'm getting a rough idle accompanied with a P0300 code. Jeep drives fine but obviously want to resolve the issue and not risk long term damage.

My rig: 2021 Trackhawk, ordered June of '21 and took delivery in September. Currently at 5478 miles. Modifications include a GT Haus cat back exhaust (installed at ~1500 miles), Legmaker intake (installed at ~2500 miles, Billet Technology catch can (installed ~50 miles), and Ravelco anti theft unit (installed at ~150 miles). PCM is unmodified on the stock tune. Always fueled with 93 at a Sunoco or other top tier station, and always watch them press the button due to some mild OCD and paranoia.

Timeline of Events:

DATE	EVENT/DESCRIPTION
5/24	CEL first appeared after making a couple stops at stores on the way home from work. Before light appeared, I had notice a bit of a rough idle to the point where the truck sounded like it was cammed. After CEL, truck driven home at highway speeds, no harsh acceleration of aggressive driving. Catch Can removed per FB recommendation related to possible vacuum leak.
5/25	Called dealer to schedule appointment for CEL Diagnosis and oil change.
5/26	Dealer dropped off prior to opening for service. Dealer called mid morning and first impression was a PCM issue. Did inquire about the aftermarket exhaust and requested remote to close/open muffler valves. Wife dropped off remote during lunch break. Dealer also questioned aftermarket "alarm" system. Explanation provide for the functionality of Ravelco.
5/27	Dealer had advised no change in misfire with exhaust valves open or closed. Commented that the misfire only occurs while idling and not tied to a specific cylinder.
5/28	Vehicle collected from dealer for long weekend after advised that there appears to be no risk of catastrophic failure.
5/29 - 5/30	10 gallons of new fuel from different station added to the roughly 1/4 tank still in vehicle. CEL did not appear but rough idle still noted. Additional code for C0572 also appeared at this time. Vehicle parked for weekend and was not driven.
5/31	Vehicle was returned to the dealer at opening for further diagnosis. Loaner vehicle requested if vehicle was going to be at dealer for additional time.
6/1 - 6/6	Dealer continued diagnosis and system testing. Complete list of tests not provided but was noted that fuel quality had been tested and passed.
6/6	Dealer advised that loaner vehicle was not available and root cause for misfire not identified. C0572 code still present advised to be related to unplugging of harnesses during diagnosis. Was advised to drive and monitor. Post collection, vehicle filled with full tank of 93 fuel and bottle of Techtron Fuel System cleaner.
6/7 - 6/10	Vehicle driven without incident totaling ~150 miles. CEL remained off but code for C0572 persisted
6/11	Battery unplugged in an attempt to clear C0572 code. Reconnected battery and drove vehicle for weekend errands in the area. After visiting a local Lowes nearby to the dealer, I stopped in to update on condition. Advised service agent that CEL had not reappeared all week and attributed the CEL to possible bad gas. As vehicle was exited the dealer, CEL re-appeared. Updated service agent and was told to drop off on Monday.
6/12	After market air intake removed and replaced with OEM unit. Battery again disconnected to clear codes and reset parameters. CEL reappeared and issue persisted.
6/13	Vehicle was returned to the dealer at opening for further diagnosis. Loaner vehicle was again requested if vehicle was going to be at dealer for additional time.
6/14	STAR ticket opened stating CEL and rough idle. Star responds to check exhaust timing then proceed to smoke test through brake booster hose and introduce propane through IAT sensor opening while running.
6/15	Dealer updates misfire persists and timing at 0.4 degrees retarded. STAR advised to check purge valve and run compression test while vehicle running, then to check airflow through exhaust at TDC. Dealer advised that attempted cam phaser cleaning. Vaccuum needle from equipment fluctuates but tech questions 12 year old gaugef.
6/20	Dealer updates that exhaust phaser cleaned, scoped cylinder and found no signs of damage. no leak down found on Cylinders 6,7 or 1,2. New vacuum gauge validates 15-17 hg with no fluctuation. STAR recommends cooling system check. Dealer advises no overheating issue, none of the plugs or pistons look "clean" and still misfires in P or N but not in D or R, normal and aggressive driving. Dealer inquires about catalytic converter restriction. STAR recommends reinstalling factory exhaust and re-evaluate concern. Service manager called and advised that likely culprit is the aftermarket exhaust. Vehicle was picked up same day and I swapped the exhaust to the factory unit in home garage. Battery disconnected during installation. Upon completion ~20 start/stop cycles before CEL reappeared.
6/21	Vehicle returned at opening and again requested loaner vehicle.
6/21 -6/25	Vehicle sat without further diagnosis - No STAR response
6/25	Loaner vehicle granted and collected from dealership
6/27 -7/4	Vehicle sat without further diagnosis - No STAR response
7/5	Dealer advised that additional testing performed to check Air/Fuel condition which appears normal. Star case advised to be commented on and will be re-opened. Internal recommendation from another tech to remove valve covers to investigate any sort of mechanical failure.

List of possible areas to investigate I've given dealer (I'm sure I'm forgetting some as it was a last minute handwritten note):

Quality

Pressure

Sending Unit/Fuel Pump

Injectors

Spark Plugs

Vacuum Leak

Throttle Body

Coil Packs

Cam/Lifters

Valve Seal

Leaking Intercooler

Bent Valve

Valve Seal

Link to FB post: Facebook Forum Posting

Trying to see if anyone has had a similar issue or possible additional areas to try. I don't want to go lemon law route. At this point I just want the Jeep fixed. Thanks in advance for the assistance!

7/8	Spoke with Girard at Jeep Customer Care and discussed car payment reimbursement. I will send a copy of statement and proof of payment. Also visited dealership and spoke with Chris L. Copy of latest star case opened on 8/8 provided. Star case summarizes previous tests and confirms P0300 still present. Fuel trims appear normal. Dealer believes could be either 1) bad catalytic converters, 2) faulty PCM, or 3) bad coil packs. Chris advised of notification to area manager requesting to begin replacing any of the above.
7/12	Star agent recommends removing blower belt to monitor vacuum
7/15	Dealer tried above test, no change to condition and vacuum measured at 19hg in both with and without accessory belt
7/18	Star asking which cylinders are misfiring and if MAP and boost pressure sensor readings match mechanical gauge
7/20	Dealer advise all 8 cylinders misfiring but not did not monitor MAP with belts removed. Star advised issue could be fuel pressure or cam timing (cam-phaser) alignment. Dealer advised fuel pressure between 57 - 65 PSI and agreed to remove timing cover to further inspect.
7/21	Star questioned if fuel pressure matches desired parameters on scan tool and if both bank O2's running constant rich or lean.
7/23	Vehicle picked up from dealer for the weekend to check grounds, relays/fuses/inspect. Broke and re-tightened engine bay grounds and applied dielectric grease to ASD fuse. Disconnected battery to reset adaptives and clear code.
7/24	Refilled fuel and added Techtron fuel system cleaner. Drove approximately 70 miles and iniated several start/stop sequences before CEL re-appeared. Observed rough idle only in P or N as dealer previously advised. D and R no rough idle. Did not notice an RPM change between gears.
7/26	Spoke with Chris L (Service Director) and Chris M (Technician) and reviewed concerns. Confirmed that computer validating misfire in P and N at idle only. Not misfiring while under load. Also confirmed he replaced ASD fuse at initial diagnosis. Could be cam phaser/cam timing, VVT Solenoid or possibly torque converter. Will follow Star direction to inspect cam phaser.
7/27	Received update call from Girard at customer care. He spoke to Chris L at the dealer who advised Girard of our conversation on 7/26. Will provide next update on Friday 7/29 or Monday 8/1.

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