what should the 4 gauge be??rail or fuel pressure
 

trans temp ,egt, is a must now the boost I am not sure it is needed? if so why? now what do you think about the rail pressure or fule pressure if Iam right an 04 will not run with out lift fuel pressure so how could you get rail pressure?so witch 3 should you have and if 4 what 4 should they be?? for most of us thanks for any and all in put it willbe good to hear what have to say?

there was a post i bit ago i will see if i can find it but if i remember right you want to know your rail psi so i would go with that

Rail pressure is not needed in a daily driver it's more for tuning purposes. Fuel pressure is more important IMO since I've gone through two lift pumps and could have been diagnosed with the gauge before they went out. But I have a manual so I have both rail psi and fuel psi :D I'd got with tranny egt boost (let's you know how hard the motor is working) and fuel psi (even if u get the AirDog it's still useful to watch for lower fuel pressure due to filter restrictions)

Boost is a good diagnostic indicator. Many things going wrong will reflect in boost level. Fuel pressure both low and high (rail) side are important. I would do both, low side first. Good RP gauges are pricey.

None of the common rail dodges will run without a lift pump. Rail psi is how much pressure the cp3 is delivering to the rail and injectors. Highly modified trucks with performance injectors can and will "drain the rail" under full throttle and that can be diagnosed with the gauge. With the mods in my sig I've never had a problem draining the rail.

What about oil temps?
Oil temperature is a direct indicator of engine load, shows proper operating conditions.
If something goes wrong, you get an early warning by the temperature increase.


I don't want to miss it.