High Altitude Package

[Harley]

Just curious if anybody knows what the high and low altitude packages are exactly and what the difference is between them. Never heard of it until now and even the ppl at the jeep dealership had no clue

[Geonovast]

As far a I know, the only difference is the CPS and possibly the O2 sensor.

[Harley]

Yeah, thats how I found out about it when I had to get a CPS. They said they needed to know which package I had so I had to have a dealership run the VIN to find out. but even they couldnt tell me the difference or what exactly it was. Thats the first I ever heard of it.

[HOrnbrod]

The Hi Alt CPS (Renix only) has offset mounting holes that advance the ignition timing about 2*, and are used for mountainous locales to prevent pre-ignition. The standard and hi-alt CPS's have two different part numbers. They should have carried this over to the HOs.

[jimoshel]

To prevent pre- ignition you need to retard the spark. Not advance it. One of the service stations money makers years ago was stations advancing the timing on tourists cars coming to the mountains. with the subsequent warning to be sure and retard it when leaving. Advancing the spark, one degree per thousand feet, helped improve combustion in the thinner air. It says on the emissions label on the firewall whether you have the Hi Altitude package or not.

[kro10000]

To prevent pre- ignition you need to retard the spark. Not advance it. One of the service stations money makers years ago was stations advancing the timing on tourists cars coming to the mountains. with the subsequent warning to be sure and retard it when leaving. Advancing the spark, one degree per thousand feet, helped improve combustion in the thinner air. It says on the emissions label on the firewall whether you have the Hi Altitude package or not.

:agree:

[HOrnbrod]

To prevent pre- ignition you need to retard the spark. Not advance it.

 

I stand corrected.

[airspeed]

My truck was delivered new in Colorado Springs ~6500' and the emission tag under the hood states above and below 4000 feet. It is good to know I need a high altitude CPS. When I put a timing light on the engine it measures 14 degrees.