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Engine stalls on rough terrain - dealer stumped.

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Old 10-25-2012 | 07:50 AM
  #11  
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Here are some images showing the layout of wiring and location.

ECU location 1

ECU Wiring Harness layout
Old 10-25-2012 | 10:07 AM
  #12  
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Thanks. I'll check that out.
Old 10-25-2012 | 11:56 AM
  #13  
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Originally Posted by thedrod
Stalling on bumps is often, but not always, attributed to loose or failing electrical connections.

Locate your JK's ecu, and while it's running, smack it with your hand and see if the problem is reproduced (idle speed fluctuation).

I've owned and seen several vehicles with failing ecus die when driving over speed bumps...but you restart and it starts right back up.

The ZJ Grand Cherokee had that problem for several years. I haven't heard of this being an issue since then, but there is always 1 that comes along.
Old 10-25-2012 | 03:33 PM
  #14  
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did the test on the ECU. Bumped it multiple times while running and nothing happened. Checked every ground wire I could fine around the top of the engine bay and they all seemed solid. Where else are ground connections?

Could something like this happen from a loose ground on the extra lights I've added?
Old 10-25-2012 | 07:07 PM
  #15  
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Default Similar issue with 2011 JK Unlimited

I have a 2011 JK Unlimited. When first purchased all was fine. Just after installing larger tires and not re-gearing (coincidence?) my JK would occasionally falter while beginning to move such as when the light turns green at an intersection and would/will invariably die regardless of the amount of throttle applied or none at all. Upon restart all is well. This has happened a couple of times when I was not in traffic and could experiment. When the faltering began I let it run and it sounded like it was only hitting on two cylinders and would continue to run for between five and ten seconds or so. Again, changing throttle amount had no discernible affect. I have discovered that it happens less frequently when the RPM's are higher when starting out. In traffic I immediately turn off the key and restart as that is the quickest way to get moving in traffic. I have taken it to the dealership a couple of times. The first time they updated the software. The second time they made other adjustments. It still occasionally does it. I will be re gearing in a couple of months so I am interested as to how it will react when it is not as strained at next to zero throttle.

Does this sound like what you are experiencing?

KG6SLC aka Eugene
Old 10-25-2012 | 07:15 PM
  #16  
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No, that doesn't sound anything like my issue. I hope the regearing fixes yours.
Old 11-07-2017 | 09:40 AM
  #17  
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Originally Posted by matt1171
I have a problem with my 08 JKU. When I hit a rough spot in the road - bad pavement, railroad tracks, transitions from road to bridge, etc., my engine RPMs will drop and then come back up. If I'm going slow enough, it will sometimes even die. If it's a really rough spot, my check engine light will come on and sometimes also the traction control light.

I have taken it to the dealer twice now. The first time they diagnosed it as the Crank shaft position sensor and replaced it. That seemed to fix the problem until about 5000 miles later and the problem came back. After 3 days in the shop they finally decided to replace the cam shaft position sensor because they couldn't think of anything else (at no charge). That didn't work. This problem seems to have my dealership stumped.

Any ideas?
This also sounds like a Crankshaft Sensor issue... here is my quote from another thread... hope it helps you.

I have a 2012 JKU. It would hesitate or hiccup on down shifting a few times during a normal drive. I drive about 50-60 miles a day to a from work, and is mixed highway and city. This would happen routinely and I couldn't nail it down. Then it did it and stalled completely... dead while rolling along at 30 mph or so... I drifted into a side driveway and attempted to start the car. It would turn over with the key, not start, and the engine would continue to turn over until i turned the key to full off. I finally unplugged the front unit (computer?) that is metal and has two large connectors going to it. Unplugging both for about 30 seconds and replugging them allowed it to work. Not wanting THAT to happen again I checked the forums and found one thing that seemed to work for most everyone... the CRANKSHAFT position sensor... not the camshaft. This part is about $16 and isn't tough to replace... videos online show it... passengers side of the engine, from underneath, one 10mm bolt, replace and done in like 10 minutes.
This seems to have brought new life to my beloved Jeep. Beautiful, precise shifting, no dropping of RPMs or hiccuping on a down shift, and Ive noticed better performance and MPGs are about 3 MPG higher than before (19 vs 16).
Because this is such a cheap part and easy to do yourself, I suggest it first.
Old 11-07-2017 | 11:47 AM
  #18  
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We had a guy in the club with almost the same issue, it ended up being the O2 sensor. He did the same as you and replaced the cam and crankshaft sensor with about the same results as you.
Old 11-07-2017 | 03:27 PM
  #19  
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I would def look into the crank position sensor and or cam position sensor.
Old 11-08-2017 | 04:03 AM
  #20  
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This might be off the mark, but your Battery is good, right ? By "good", I mean load tested, connectors removed, cleaned, reinstalled ( if you have the so called spring clamps, they break and loosen).
Also the fuel pump circuit, loose connectors, damaged wire in harness, check with multimeter ?
Since you had already replaced crank and cam sensors, figure back to Basics. Battery, grounds, harnesses.
Hope you get it Solved !


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