Hello all Jeepers, I encountered an usual start issue yesterday while offloading in the mountains of Colorado. At one stop, when I tried to start up my 2013 JK, the engine would start, and immediately would die. This operation went on through multiple tries. After trying holding the throttle down, the engine would keep cranking without the start. Finally, after about 15-20start tries, the engine started normally, it also performed as normal. My friend that was along with me has 2012 JK, and he had the same problem about an hour earlier. We did not have any problems before, nor after the episodes. Could it be a fuel delivery problem? We both had fueled up at our regular stations that morning. Temp. Was about 50 degrees, altitude about11,000 feet. We have been on this trail many times with no issues. Any ink or,at ion would be greatly appreciated. Thanks,

 

I would be curious to know what altitude the previous ignition cycle was prior to the hard start on the trail; and how far you drove to get to the trail?

 

Sorry for the delayed response, been busy. The day in question was a cool fall day, the temp. in mid 40's. The drive from town to trail start is 27 miles, a easy highway drive of 55-60 mph. The trail is fairly steep, no big obstacles or hard climbs, just rough rocks, about 6" to 12" dia. Altitude ranged from 8,000 ft at start, 6-7 miles in, is about 11,000 ft. Took about 2 hours to reach summit. The first start issue was about elevation 10,000, and the second at about 11,000 ft. W stopped along the trail at about 9,500 ft. just prior to the first start issue.The second start issue was about an hour later. We have done this trail many times in the past four years with no issues. There have been no issues since. All seems ok.
Thanks

 

I'm glad to hear its good now. FYI Chrysler uses a speed density OS with no maf sensor for actual airflow calculations, so it uses look up tables for calculated airflow.

When you turn the key on a baro reading is stored for air density calculations read off the MAP sensor.

Works well most of the time. In the early days of FI starting at low altitude the traveling to high altitude on the same ignition cycle could cause drivability issues since the baro reading was off. Some manufacturers added a baro sensor and others didn't, having a MAF helps because it can sense air density at different altitudes.

Some owners manuals would tell you to cycle the ignition after several thousand feet change to get a new baro reading.

Modern speed density OS' s handle altitude change well but sometimes a large change in altitude and adding different fuel can confuse the adaptive fuel trims.

 

I encountered this exact problem wheeling between Idaho Springs and Georgetown a couple of weeks ago. I still don't know what the issue was.