My new 08 engine in my 07 JK. Ran about 3 miles before running rough. No codes thrown. Checked plug wire tightness. Took the plugs out...still looking good. Swapped the coil pack...same result. Crankshaft position sensor us strangely different from 07 to 08. Any immediate thoughts come to mind? Simple solution?

 

I had a simular issue. One of my plugs (E3) went bad even though it looked ok. Swapping it out solved the issue. That was the first time ever i've have a plug die on me

 

look hard at the crank position sensor....make sure it's attached securely and is not hitting over so often.

 

Is that the one that's directly above the water pump?


Checked the plugs and they all looked good...

 

I did just read about the recall on some '08 engines with the wrong spark plugs put in by the factory...nice...

 

Are they the orignal plugs? If so...... change them, I'm still running the orignal plugs because they are still on warinity but as soon as its up its gonna get different type. I've had my 09 in 3 times for rough running and they change plugs and it goes away for a bit but then comes back again. The plugs all looked good but they failed. This was only at idle, and it would backfire sometimes under load. but it was very driveable.
Did the 08 eng run smooth befor you pulled it? Did you make sure all the connectors are clean and tight? grounds?
If the crank position sensor was bad it would throw a code. If a sensor was bad it would show up on the computer.
How rough running is it? Rough at Idle? cruise? speeding up/load?

 

My Silverado crank position sensor was improperly installed on the truck new. It was spaced too close and would make the slightest contact at higher rpm's. A shuddering miss was the result, ever so often. NEVER SET A CODE. Don't depend on a code being set, some situations arise and will never set a code . If the sensor voltages are okay, a quick blurb won't show up as a miss.

 

That's the cam position sensor.

The crankshaft position sensor is on the bell housing, right side, for the automatic.
I assume for the 6 speed it's in the same location.

 

So it sounds like I checked the wrong one then...anyone have a pic of where the crankshaft position sensor is? Easiest to get to from the top or the bottom? Right side as you look at the engine or right as in passenger side?

 

Right and left for me is always as if sitting in the driver's seat facing forward.

The crank position sensor is visible from underneath, on the right side of the bell housing.