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No power inclining, bad gas mileage, random misfire code


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angies719
New User

Dec 11, 2013, 2:27 PM

Post #1 of 9 (1595 views)
No power inclining, bad gas mileage, random misfire code Sign In


I just purchased a 2010 Jeep Patriot 2.4 4wd limited with the cvt transmission. It has 41k miles and one previous owner. The first time we took it out of town we had to travel up several inclines n the road and it damn near rolled backwards. I had cruise control set at 65 but on incline it dropped to 40, the car downshifted and the rpm's revved to almost 6 and would not stop so I quickly de-activated the cruise and resumed the incline by pressing the gas, however, could not get my speed above 50. A check engine light flashed multiple times then stayed on. I had the codes pulled at the autoparts store and it came up random misfire p0300. Took it back to the dealership they played dumb and reset the computer. On the way home it did the same thing. I replaced the spark plugs thought it was running better and took it back to the big hill and it did it again. Also it is only getting 14mph in the city and 19hwy. I purchased the 4yr extended warranty and glad I did, but if its the ECU I don't think its covered. Any suggestions on what this might be.

Crazy


Discretesignals
Ultimate Carjunky / Moderator
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Dec 11, 2013, 7:58 PM

Post #2 of 9 (1576 views)
Re: No power inclining, bad gas mileage, random misfire code Sign In

If the engine is misfiring, you won't have any power going up hills. It would be like a one legged man in a arse kicking contest or trying to climb a 30ft ladder with a 8ft 6x6 pressure treated post tied to your leg . Someone needs to find out which cylinder(s) are misfiring. P0300 is a random misfire code and basically means more than one cylinder is skipping. Once they determine which cylinders are missing, they need to figure out why.

Another thing to worry about is the check engine light flashing. You should not be running the engine with a flashing check engine light. If you have enough misfires and they are caused by mechanical or ignition related problems, you'll turn your catalyst into an incinerator. The cat's temperature can become so high that it melts the substrate. Then you'll have a potato of charred ceramic plugging up the exhaust.





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(This post was edited by Discretesignals on Dec 11, 2013, 8:08 PM)


DanD
Veteran / Moderator
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Dec 12, 2013, 5:06 AM

Post #3 of 9 (1549 views)
Re: No power inclining, bad gas mileage, random misfire code Sign In

The cat might be the problem to begin with?
If it's partly plugged it would run fine with light driving; but put your foot into it, it can't breath. May also explain the crappy fuel mileage.
Have the exhaust system checked for excessive back pressure. You want to have less then 1 pound of pressure throughout the whole rpm range.

Dan.

Canadian "EH"






Derekjfarrington
User

Dec 13, 2013, 1:31 AM

Post #4 of 9 (1535 views)
Re: No power inclining, bad gas mileage, random misfire code Sign In

on an ignition note does it have individual coil packs or 1 coil. the gf has a mustang and I swapped plugs and wires across and still got a random misfire on hills. after buying injectors i figured id throw a coil at it since that is something that apparently cant be bench tested and was cheaper. sure enough runs like a top now. if anyone needs some 3.8l injectors i dont think she'll miss her xmas present


angies719
New User

Dec 16, 2013, 3:49 PM

Post #5 of 9 (1510 views)
Re: No power inclining, bad gas mileage, random misfire code Sign In

Well, its in the shop. When driving with me they said it's the transmission, but after looking into it they said it is the catalytic converter. So hopefully after replacement it will stop, but we shall see. I'll post back after I get it back and let you know how it's running.


kev2
Veteran
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Dec 16, 2013, 5:25 PM

Post #6 of 9 (1506 views)
Re: No power inclining, bad gas mileage, random misfire code Sign In

FYI catalytic converters have an extended warranty @8years and 80k miles


angies719
New User

Dec 26, 2013, 9:51 AM

Post #7 of 9 (1469 views)
Re: No power inclining, bad gas mileage, random misfire code Sign In

Got it back from the shop. They replaced the cat and another converter as well as 4 gaskets including the exhaust gasket. It accelerates great now and inclines without losing speed. The gas mileage has improved to 19.5 city and 22 hwy. So its still below what it should be (23/28) but better than the 14.Laugh


angies719
New User

May 14, 2014, 10:29 AM

Post #8 of 9 (1285 views)
Re: No power inclining, bad gas mileage, random misfire code Sign In

Soooo, the cat is going out again! It's only been 5 months since it was repaired/replaced. Not sure what could be causing the cat to go out but I'll be sending it back into the shop and update once I find out.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

May 14, 2014, 12:52 PM

Post #9 of 9 (1282 views)
Re: No power inclining, bad gas mileage, random misfire code Sign In

A poorly running engine is what usually contaminates a Catalyst.



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