I have a new rail pressure guage on my 06 and ive had a little problem. Soon after install i started to get a little stumble at idle. It got a little worse then today im driving my mom to Oakland Airport and the thing dies on me twice. (in East Oakland and i only had one gun with me)

i limped it to the terminal, kicked mom out and drove to a gas station. I had set a code for railpressure sensor and suspected the problem was a connection. I popped the hood and took the wire out of the sensor and reinstalled the stock harness and no more problem. Ran great after that.

Whiile the stumble/stalling was going on it sounded like it was running on about two holes. The guage read 26000 at idle, no way it could be that high.

Got back to Winspeed in Martinez,called Quad and they said try some di-electric grease. I did and re installed quad wirring, same problem. I started to wiggle the harness and it is the female side of the quad wirring connector. Seemed to be very loose and flexible.. any way sending it back to Quad in the morning. Not bashing, just want others to be aware if thier trucks start acting the same.

 

did you check all your connections? I called them to check on the two ground terminals. the smaller one is for fuel pressure. they said just zip tie it up out the way

 

Did i check all the connections?, yea of course, i posted that i found the connection that was causing the problem. I have the fuel pressure as well so the smaller one was actually hooked up and working it was only the rail pressure that was a problem.

 

If you unplug ( or have a bad connection ) at the rail sensor, the cp3 maxes out the fuel pressure. Yeah, 26000 is very possible for the cp3 to produce, but more than likely it was reading irregularly. When rail pressure is that high, the new CR engine sound worse than an old 12V ! Knocking loudly, but they shouldn't run rough.

 

You just have to make sure the stock connector is seated tightly in the molded side of the connector. Worse case scenario run a zip tie around them.

Look at the plug and make sure all the pins look good and nothing is too short. We can get you a new wiring harness but, the plugs are the same. The plugs are also the same as all our modules.

 

Qzilla, I was able to reproduce the problem by pushing the stock connector into the molded connector and by squezing it slightly. I looked at the pins on both sides and could not see anything that looked bad. I tried to ziptie them together but it still was not connecting well. Either too tight or too loose.

it was as if the molded, male side of the tee harness was to pliable. It was not holding its shape when plugged in. The plastic itself seemed very soft and rubber like.

I love the guage so hopefully a new harness will work. I shipped it back this morning.

 

It sure sounded like it was dropping clyinders or running out of fuel. Never heard a diesel 12v/24v/CR sound like that before.

 

Mine did the same thing. I unplugged it and plugged it back in and it ran fine. Seems like the connection can be tempermental. When it is not a good connection, the truck "chugs" like a v-8 with a huge cam and pegs 26k on the gauge. Love the gauge, just had to work the connections and apply plenty of di-electric.

 

We tried everything we could think of, zip ties, stuffed a little paper into it to hold it tighter, di-electric, I connected and re connected it several times. I could not get it to run for more than 5 mins without a problem.

 

I had the same issue with my truck. The dealer ended up putting a new rail press sensor in, but they blamed the resistance from the Commander's wire tap. I haven't hooked my rail press back up, because I'm afraid it will do it again. I never really monitored rail press anyway. I got a P0192 code when it happened (low rail press). Your right, the truck sounds like it's going to come apart! Other than that issue, I love my Commander, and I don't mean to bash Quad, because they have always taken good care of me. I just don't have the rail press feature now...

 

mine did the same thing as yours. i havent contacted quad yet, so im not going to complain, but its a pain. i just plugged it back into itself so it doesnt get the plugs all dirty, but i couldnt drive with it doing that. and the fp reading is very inaccurate. it never leaves 9-10 psi no matter what i do to it with the smarty or stock. neat little gadget, but im going to see if i can send it back for a refund

brett

im getting the fp reading from the bottom of the fuel filter housing since the jake's vacuum pump is in the way for the cp3s banjo bolt

 

I would not say it is inaccurate at all. Do you have something else that would say that your fuel pressure is dropping?

They don't all just drop like a rock when you give it throttle. That is why some trucks can make 500 rwhp on a stock fuel system and some cannot make 400 rwhp without a pusher pump.

 

im blaming it more on the location than anything. i do not believe that my stock fuel system is keeping a steady 10 psi flow when i am lugging the motor and literally blacking out lanes of traffic with thick smoke. am i doing any damage to the gauge by plugging it back into itself. it reads a steady 360ish reading

brett

 

Rusty, I had my F.P. sending unit on the CP3 and it reads at about 6-7 at idle and 9-10 cruising. At WOT it stays at or above 9.

The Rail pressure was reading about 7500+- 1000 at idle and 16K-19K at cruise (50-65% load) and 22K+ at WOT.

 

Well please let us know what happens when you do hook it back up. Id be curious it still does it with the sensor.