2014 jk 3.6 long crank.

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Nov 21, 2020
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My wife's 2014 jk has an interesting quirk. Ever since we bought it, it occasionally displays a long crank before starting. We live in Houston at sea level, and there is neither rhyme nor reason as to when it will do it. We spent the winter up in Estes Park Colorado for 7 months, and the whole time we were there, it never long cranked, not even once. We were at 7500 ft elevation and in the dry cold. Does anyone on here have any idea if the elevation and humidity/temperature change could directly correlate to the random long crank? We are now back down here in Houston and the long crank has started rearing its head again. It has been very hot and very humid. Nothing has changed other than the environment we were in while staying in Colorado. Any ideas as to what to look for? Thanks!
 

dishdude

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Are you able to get live data? It would be interesting to see if the crank sensor is showing the engine rotations when this happens.
 

Imadentguy

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Are you able to get live data? It would be interesting to see if the crank sensor is showing the engine rotations when this happens.
This was going to be my next step. I do know that the 14’s had an issue with bad crank sensors but when i checked the pn on the sensor it did not fall under the bad batch with the info provided from chrysler.
 

Imadentguy

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I'm going with a bad Temperature Sensor
I thought about that, but we have issue with it down here in Houston even during cold weather. In Co temps ranged from 75 to -20. Never had one long crank. In Houston the long crank has happened from 100+ to low 30’s high 20’s. I feel like the long crank is happening more and more often.
 

Imadentguy

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I'm going with a bad Temperature Sensor
So i did a little research…. Man i hope that you are referring to the coolant temp sensor and not the oil temp sensor. Ect ez….. oil temp sensor not so much…
 

Imadentguy

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Check the condition of the Coils. Maybe the Humidity is causing one to short out.
Hmmm what should i look for? Seems like the hotter and more humid it is the more it long cranks at start. Started it this AM and it popped right off. Started it about 2 minutes ago and sure nuff it long cranked….will add no CEL and 38k miles.
 
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Your tech or dealer wishes it would throw a CEL too, since most mechs that have an ounce of troubleshooting skills.

Simple stuff.... maintenance... plugs, air filter, FI cleaner or two, oil level...

Fuel prime..... turn key on and make sure dash all lights ups, wait a few seconds, then engage the starter.

Grounds.... too common of an issue. I would clean all grounds, and battery/alternator/starter cabling, chassis grounds etc...
 

Imadentguy

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Nov 21, 2020
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Your tech or dealer wishes it would throw a CEL too, since most mechs that have an ounce of troubleshooting skills.

Simple stuff.... maintenance... plugs, air filter, FI cleaner or two, oil level...

Fuel prime..... turn key on and make sure dash all lights ups, wait a few seconds, then engage the starter.

Grounds.... too common of an issue. I would clean all grounds, and battery/alternator/starter cabling, chassis grounds etc...
Maintenance is on point. I wondered if maybe a fuel pump. I have trued turning key and letting it prime good and it seems to make no difference. I just hate to throw parts at it. CPS is cheap and rasy enough that i may just throw one on there and see if it makes a difference. Its just so random. It long cranked this afternoon, but it may be another 10-20 starting cycles before it does it again. By long crank i maybe should clarify that it is not excessive, but is more like 5-10 rotations more than usual before it pops off. When it is behaving it pops on 2nd or 3rd rotation. Good idea on checking grounds.
 
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Altitude related? Barometric pressure sensor/map? Lean calibration? Perhaps there's a tsb and re-flash for the issue?
 
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TIPM is probably getting moisture or has corrosion. I know they had a problem with fuel pump so there is a add on relay to convert relay from TIPM to external. Some say dealers will fix for free but that was couple of years ago. Dealers had everything. Here's the story.
 
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Imadentguy

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May be trying to find cylinder 1? Cam position sensor?
So if a sensor is out of spec, why do they not throw a CEL. Seems like it would make run ability issues so much easier to diagnose. Had a bad coil on my 17 superduty 6.2 that caused a hard miss at idle, and it never threw a light. Seems absurd by this point in terms of technological advancements that have been made in the automotive field. Thanks
 

Imadentguy

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Altitude related? Barometric pressure sensor/map? Lean calibration? Perhaps there's a tsb and re-flash for the issue?
Hmm good idea. Map sensor is quick easy and cheap. I will replace it here in the next week or so and report back/ go from there. Thanks!
 

Imadentguy

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A guess, the fuel pressure regulator is leaking.
Thank you for the reply. That sucks because i am pretty sure the regulator is integrated into the sending unit. If i do a fuel pressure test am i wrong in assuming that the only time the pressure would read out of spec is if the vehicle were to exhibit the long crank scenario?
 
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