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Discussion Starter #1
Last year 2018 in June I had these same codes come up with really rough idle. I changed spark plugs and wires and it came back a month later. I took it to a mechanic and he couldn't find anything wrong with it. Of course it drove fine from there on.....now a year and a half later it started doing it again last night. I just had it sprayed at Krown the day before. Could oil have gotten into some electrical? I also had an O2 censor code come up yesterday before I cleared it. It didn't come up this morning. Anyone else have the same issue and figure this out? I know it could be a lot of things.


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Discussion Starter #4
I went ahead and ordered a new crankshaft speed sensor. Itll be in tomorrow. If that doesn't fix it I'll try o2 sensors. Does anyone have anything bad to say about NTK o2 sensors ? They will be $180 less than the mopar. Anyone else have any thoughts on what these misfires could be on a 2015 2dr jk? Plugs and coils were replaced about 15 months ago using ngk plugs and standard motor products coils. I smell alot of gas when my jeep is idling.
Thanks for any help I love driving my Jeep and want it back asap.

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Why would you order a crank sensor for that? You need to diagnose the problem and stop throwing parts.

The key here is looking at live data on a scan tool. Look at o2 sensors and fuel trims. My bet is a misreading upstream o2 sensor is pushing fuel trims high which is causing rich on a downstream. But need to look at scan data to really see.
 

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Discussion Starter #6
Yes you are right. I read and watched alot and a few people had their similar issues solved with a new crankshaft sensor. But I am having a buddy come by tomorrow with a scanner. I disconnected the battery and ran it and its showing only the p0174 code right now but I can still feel it misfiring. I'll wait for the live data. Thanks !

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Discussion Starter #7
After 2 new upstream 02 sensors it seems to be idling nice and no more codes after a few short drives and about 10 min of idling. Here are the before and after fuel trims. I have 2 new downstream ones should I just save them for when they go or replace now while the fenders are off.


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Wow your short term was very high. Explains the lean code. Hope you got it with an O2 sensor. Ideally you'd look at that data and also the bank2 upstream o2 sensor before you bought the parts. Then you'd know of it was an o2 sensor problem or it may have been a vacuum leak.

Can you take the downstream o2 sensors you bought back? You really don't need them.
 

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Discussion Starter #9
Drove it for an hour and a half and it's been running great. Victory beer commencing.
Thanks !

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