I have had my performax gauges installed for about a month now. Very happy with them by the way. Just wondering about my rail pressure. While sitting at idle or driving my gauges is constantly jumping +-500-1000 psi. Is this normal??? Or is this gauge suppose to read steady like all my other gauges? At idle it never drops below 6000 or so. Just wondering if maybe I had a tiny leaking injector or something. The truck has 91000 miles on it with original injectors. Thanks in advance.

 

I don't know if the performax gauges are mechanical or electrical. I have electrical (Quadzilla). I see about that same type of fluctuation. But it really depends on the situation. At idle I see between 6100 - 7100psi.

 

The true pressure should not fluctuate that much.If it were my truck I would hook up a scanner and compare the actual pressure VS the comanded pressure and compare that to what your gauge is showing

 

The performax rail pressure gauge is very responsive. It will pick up the smallest change in rail pressure. My 05 does exactly what you are describing.

Paul

 

just installed same performax gauge and mine does it too

 

The real pressure does fluctuate that much. When I first had my Pricol RP gauge I was amazed how much it moved at idle, and unlike the performax gauge the Pricol has an "averaging" logic built in. Since the RP gauges don't have their signal processed thru the ECM the output is very very fast, much like an analog boost gauge vs reading it thru the OBDII port, its just much faster.

I would suggest you do some more research before telling a guy his truck is messed up, when it doesn't have an issue.

Simple things like alternator, a/c, steering, etc loads make huge changes in the rail pressure since the fuel flow is slow and the rpms aren't there to make rapid changes thru the FCA.

 

If I remember correctly, in the service manual for my '05, it states that rail pressure at idle should be 6500psi +/-500psi. You gauge seems fine. I also have a Quad commander unit and it does the same thing & read similarly. You're fine.