N14 celect plus intake manifold pressure

[allen pardon]

I changed the sensor thinking it was bad but even after the new sensor was put in, nothing changed

 

[mekanik]

Process of elimination says ECM then.

 

[allen pardon]

That’s what I’m thinking. At least it has been running so I think it will make it til Christmas and I will take it out of the truck and get it tested. Thanks for the reply

 

[Truck Shop]

The NTC 475 Cummins with twin turbos and variable timing could pull 48 on boost. Detroit DDEC V would pull
50 psi on boost. But 40 is high depending on compression ratio and who knows what CPL the engine or turbo is.
The trouble with these electronic thread problems is getting all the correct info in exact order.
It's the usual dart shoot.

 

[63 caveman]

as long as we are throwing darts.....
I would look at the throttle position and switches for loose connections or intermitting connections (as well as fuel solenoid), I'm not sure that if the ecm is seeing the wrong boost pressure that it would cause back firing?

 

[allen pardon]

as long as we are throwing darts.....
I would look at the throttle position and switches for loose connections or intermitting connections (as well as fuel solenoid), I'm not sure that if the ecm is seeing the wrong boost pressure that it would cause back firing?

The fuel pedal and harness was replaced 2 years ago along with the fuel pump and I changed those because at certain times when I would make a turn I would loose throttle response but that did not fix the issue then. Like I mentioned in a previous post, just after Christmas I will pull the ecm and have it tested

 

[Pony]

Just out of left field, from a non mechanic, what's the chance your new manifold pressure sensor is no good?
Can you confirm its correct operation in any way?

 

[allen pardon]

I’m not sure if I can test it other than putting another one in. The one I took out was only 1 1/2 years old I think. This problem started after the rebuild and I’m just getting ideas as to what to check. I will be calling Cummins back tomorrow about this. They are open 24/7 for tech support but the guy I talked to today said he just knows general things and I should call back tomorrow.

 

[Birken Vogt]

How many wires does the sensor have? Frequently, you will have one wire grounded. One wire fed +5 volts or something. And the third wire returns the value to the computer. Apply shop air to the sensor at various pressures 0-50 psi and see what the third wire says. Should vary between ground and the +5 volts. However some sensors are pulse modulated instead. These are harder to troubleshoot. You need to find the troubleshooting procedure for your particular unit. Make sure the ground and +5v is present at the sensor. Then make sure the variable signal is making its way all the way back to the computer. After that you can condemn the computer.

 

[allen pardon]

How many wires does the sensor have? Frequently, you will have one wire grounded. One wire fed +5 volts or something. And the third wire returns the value to the computer. Apply shop air to the sensor at various pressures 0-50 psi and see what the third wire says. Should vary between ground and the +5 volts. However some sensors are pulse modulated instead. These are harder to troubleshoot. You need to find the troubleshooting procedure for your particular unit. Make sure the ground and +5v is present at the sensor. Then make sure the variable signal is making its way all the way back to the computer. After that you can condemn the computer.

I just done that today, I do have the 5v at the sensor but when I applied the air to the sensor, there was no change to the value from the ecm. I checked the continuity of all three wires and all tested good so that leaves me thinking that the ecm is stuck on stupid

 

[Birken Vogt]

Leave everything hooked up. Back probe the signal wire that goes into the ECM and verify that it is delivering a variable voltage to the ECM when you apply pressure to the sensor. Continuity checks are not good enough when this much money is on the line. You need to be 10)% sure the ECM is actually receiving the signal.

 

[Nige]

I'm with Birken. The only sure way to test out those 3-wire (ECM-supplied +, GND to ECM, and signal) sensors is to have them hooked up to the wiring harness and have a set of connectors for the DMM capable of back-probing the connector pins. I refer to them as spoons, maybe they have other names as well.

Without knowiing what pressure sensor this particular one is then it could be a PWM type that would require a DMM capable of measuring duty cycle in order to measure the sensor output signal.

 

[mekanik]

Just a thought. There is not a bent pin in the connector at the ECM?

 

[allen pardon]

I checked that and all pins seem straight and I also cleaned the harness and pins

 

[allen pardon]

Guys i want to thank all of you for your help.. It turns out that my diagnostic laptop was the faulty part on the boost pressure. I have boost pressure to from my sensor. but however i did finally found the whole problem with my performance issues. Turns out i lost #3 injector intermittent and was able to see that when i dropped the cylinders. i have done that test many times without it showing up bad. i pulled the injector today and will put the new one in tomorrow. i had new pass troughs put in during the rebuild but like i said, i used the old injectors which was only 2 years old and found that oil got pass the harness into the pass through which in turn shorted the injector out. when i install the new injector, i will let you know if my problem went away

 

[funwithfuel]

So, couple silly questions. First, have you verified that the wires for the boost sensor are in the correct cavities? You said you checked continuity, did you check for correct orientation and cross-bleed? Second question, do you have Jakes or C-brakes sitting on top? When were they last overhauled?

 

[allen pardon]

Yes actually I bought a scangaugrkr and the boost pressure shows just fine on it. That’s when I done the cylinder test again and found #3 dead. However while driving the cylinder comes and goes whenever it feels like it. I will be getting the new one tomorrow and putting it in.

 

[allen pardon]

So, couple silly questions. First, have you verified that the wires for the boost sensor are in the correct cavities? You said you checked continuity, did you check for correct orientation and cross-bleed? Second question, do you have Jakes or C-brakes sitting on top? When were they last overhauled?

The jakes was overhauled with the engine 3 months ago

 

[funwithfuel]

If the problem persists, i would plug the oil supply to the Jakes, and drive it around a few weeks. See if that leads to anything.

 

[funwithfuel]

The solenoid dictates injection volume, i don't think it could possibly cause a backfire. The injection is still mechanically actuated via cam and lever. Have you inspected the rocker box for a crack in the center section? Have you checked overhead adjustment for that cylinder? Finally, with the rockers loose, if you blow air in through the injector opening, can you hear air escape through intake or exhaust? If you never generated an error, i find it unlikely that the pass thru oil contamination is the root cause. The celect were very simple and logical. No fault, no problem ( at least electrically) that's why I feel you wanna look for mechanical faults or external influence.
Just my opinion, good luck and keep us posted, please.