Engine Codes P0744 P0300 P0301

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Thupertrooper
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Joined: Sat Jun 15, 2013 10:17 am
Location: Mesa,AZ

Engine Codes P0744 P0300 P0301

Postby Thupertrooper » Fri Nov 01, 2019 11:35 pm

2005 OR 150k miles
Last 30k miles on 35s 500-600lbs camping gear always
Oil changes routinely



First time I have actual engine codes beside the emissions ones but actually lost power under load.
Went on a out of state trip but on the way back my check engine light came on for the second time ( for these codes) but they stayed and have to semi limp home for about 150 miles. Not actual limp mode since I could do 65+ mph downhill and flat straights. Any hill or incline the engine would down shift and scream 3-5k rpm just to stay over 45mph. Very low but loud scream out of the Volant CAI , not common but sounds like a new exhuast system. Could be the misfire backfiring into intake.
So I realized the misfire could be a coil so I swapped with cylinder 2 same outcome. Went ahead and ordered cheap coils off Amazon for a test with new Platinum NGK plugs since the Iridiums (about 30k miles in) looked wore out ground side.

Put it together and it runs the same. Didnt compression test didnt have the proper extension.

Idles fine till the light turns on. The light is not on all the time but will flash underload( uphill/incline) didnt have the code reader during the actual trip but did check once I got home.

Timing Chain I believe is stock
Catalytic converter stock

These are just symptoms with a random issues I em currently stumped with. Out of 6+ years of ownership only time I couldn't figure it out.

Thanks guys


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Thupertrooper
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Joined: Sat Jun 15, 2013 10:17 am
Location: Mesa,AZ

Postby Thupertrooper » Sun Nov 03, 2019 2:54 pm

Update

After some driving around tests and getting actually stranded I realized the truck ran worse the hotter it got. Led me to believe the catalytic converters were getting clogged. So I did another test, I disconnected the secondary Cats (primary are alot more difficult to disconnect) and confirmed it is restriction on the exhaust. Engine idles battery more power meaning Im able to drive it to a muffler shop and get them swapped out along with a new y pipe and muffler.

I will update after I get this taken care of. Hopefully its good again as im doing minimal effort repairs. No longer think its worth it for me.

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Thupertrooper
Posts: 674
Joined: Sat Jun 15, 2013 10:17 am
Location: Mesa,AZ

Postby Thupertrooper » Tue Nov 05, 2019 7:38 pm

another update

I had totally forgot the the primary cats are known to burning up and fall apart going into the secondaries and clog up the system. That being said I had the option of replacing them but my check engine turned off after just removing the secondaries. I rarely drive the Pathy so I will not being replacing them just bypassing them. Basically an offroad vehicle.


After all this the Pathy is running good again almost had to part with it.


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