What do you mean by a P1?

"This would be costly and very time consuming, cheaper to buy a P1 and be done with it, beats begging for a jump or walking when it is below zero."

I'm just trying to decide which is the better router, buy the Jeep upgrade kit, replace the glow plugs, controller and reprogram the computer, or just replace the glow plugs with Etecno. While it is unusual for it to get below 0 around where I live, it did get to -10 in the winter of 2010-2011, and I am not looking forward to being stuck.

What does the EPA have to do with glow plugs?

Since Glow Plugs are cycled on and off as the engine first starts up to improve combustion and reduce emissions of raw unburned fuel, Glow Plugs are considered an emission control device, not just a starting aid. Changing any part of the Glow Plugs from Ceramic to steel can create a new round of potential tests may have to be run. Since the EPA regulations are written by Idiot Lawyers who could not get a job any place else, instead of by Engineers who have a chance of knowing what they are doing, you have total stupidity.
The EPA is going after your Char Broiled Berger next, not just your glow plugs.

With out stepping too far over the line of Politics, I would support whom ever would fire, lay off, or retire most of the Federal Government Regulation Writers.

EPA=IDIOTS ON STEROIDS

The EPA does not give a Fecal (Polite way to say the S word) about Quality of parts like glow plugs. They just care about compliance with their Regulations right or wrong based upon established fact or Junk Science.

You guys are talking about two different operating modes.

1. EPA - the glow plugs are used at 20C coolant temps to help with combustion to minimize hydrocarbon emissions. They help assist with more complete combustion. During the emission cycle the glow plugs are used at about 55% duty cycle for roughly 120 seconds. Then they shut off. That is the extent of what is needed to meet government regulations.

2. At cold start -10 F and similar. Glow plugs go through a "pushing phase" (12 volts) for two seconds to bring them to peak temperature to aid in starts. They then have a high duty cycle around 75% to maintain temp for smooth running for about the first 4 minutes of running.

There is a lot of background engineering involved in optimizing glow plug operation for cold start including placement, protrusion in cylinder, temperature, etc. to make them function optimally.

Here is the gist: Ceramic glow plugs have a peak temp of around 1300 F and metallic glow plugs top out at 1050F. Ceramic glow plugs are designed to split twos hole of the injector spray nozzle, thus catching fragments of fuel atomization. Metallic glow plugs can handle "spray on", one injector hole spraying directly on the glow plug tip. The problem with spray on plugs is that they cause higher emissions when the glow plugs are not in use, so most manufacturers do not design in this manner any more.

Whether you use the 7 volt drop ins or the 5 volt mopar, the startabilty will be less optimized than the ceramic units by design. The cylinder head would need a redesign to be optimized.

We have tested all of these for the OEMs, for Bosch and Etecno. In the end, if in a very cold climate, we suggest cycling the glow plugs a couple times before cranking the engine if using metallics. It helps dramatically and is the best compromise based on the hardware limitations.