c15 acert runs rough
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dwane

Waterloo, Canada

#1 Sep 20, 2012
I have an 04 c15 acert when I start up till it gets over 150 degrees it runs very rough coughs sppits and blows black smoke from 1200 to 1400 rpm after 150 degrees it goes away but still seems a little off anyone know what might be the prob?

“Cat & Cummins ECM programs”

Since: Jun 12

Marion, IN

#2 Sep 20, 2012
Is the check engine light coming on at all? Do you know when the last time this engine had the valves adjusted & the rocker arms inspected?
dwane

Waterloo, Canada

#3 Sep 20, 2012
Ken Mech wrote:
Is the check engine light coming on at all? Do you know when the last time this engine had the valves adjusted & the rocker arms inspected?
. No check engine light valve set done 20000 miles ago. Cylinder cut out tests were all good
Ken

Marion, IN

#4 Sep 21, 2012
I'm assuming that you've changed the air filter(s) sometime in the past 18 months? Air-flow restriction can cause those symptoms, but most likely your fuel pressure is too low.

We had an 04 MBN serial number Acert, and it would blow smoke @ startup, smooth out some when warmed up, then it would occasionally skip or miss going down the road. They sent the truck to Kenworth twice in one month BEFORE I started working in the shop & spent $1800! First thing I did was put a mechanical fuel pressure gauge on the fuel return line...only had 25 psi! I shimmed the spring inside the transfer pump with a 5 cent piece of brass...70 psi fuel pressure. After that the truck quit smoking, missing & was outpulling half the fleet :)

Don't let a dealer "charge" you to connect his computer, because the Cat ET program will not show the actual fuel pressure. The only way to accurately check it is a mechanical gauge. Don't let them sell you a new "fuel transfer pump", because Cat does sell an upgraded "spring kit", with a stiffer spring, and it's much cheaper. Good luck!
dwane

Waterloo, Canada

#5 Sep 22, 2012
Yes changed to fleet air filters in july. I had someone tell me that oil could be getting into the injector harnesses. Could that b a cause?

“Cat & Cummins ECM programs”

Since: Jun 12

Marion, IN

#6 Sep 22, 2012
dwane wrote:
Yes changed to fleet air filters in july. I had someone tell me that oil could be getting into the injector harnesses. Could that b a cause?
The injector & VVA/Jake harness wires are constantly covered with oil when the engine is running. If any of those wires "shorts out", or starts sending inconsistent voltage readings to the ECM, the check engine light will come on, and a code will be placed in the memory.

I really think your fuel pressure needs to be checked. If you want to try this, without checking the pressure first, it won't hurt anything...might even solve the problem!

You will need a brass ferule from a 1/8 inch brass union (the kind used on the small shifter air lines). On the very front of the engine, drivers side, is the fuel transfer pump. It will have two or three fuel lines connected to it, depending upon the return fuel set-up. On the side of this pump, facing you will be a 5/8 bolt. Remove this bolt, but do so slowly and keep it from "popping" out when you get it unscrewed. There will be a spring with a small metal rod running thru the middle of it. Remove the bolt, spring & rod. Inside the bolt head you will see that it's hollow inside the threads. Place the brass ferule inside the bolt head, with the hole inside the ferule facing upward. Set the spring inside the bolt head, resting it on the ferule. Place the metal rod inside the spring, then carefully re-install the bolt head to the pump, keeping the spring & rod in place while doing so. This will increase your fuel pressure by 40 to 50 psi. If it solves the problem, leave it alone. But if not, you can always easily remove it!
dwane

Waterloo, Canada

#7 Sep 23, 2012
Will this affect my fuel mileage?
Ken

Marion, IN

#8 Sep 25, 2012
dwane wrote:
Will this affect my fuel mileage?
Yes....you will get BETTER fuel mileage and walk up hills when you have the proper fuel pressure available to the injectors!
Joe

Burnaby, Canada

#9 Nov 29, 2012
Where do you check the fuel pressure. I am new to an assert. There is a quick connect by the fuel primer pump would this be it.

“Cat & Cummins ECM programs”

Since: Jun 12

Marion, IN

#10 Dec 1, 2012
Joe wrote:
Where do you check the fuel pressure. I am new to an assert. There is a quick connect by the fuel primer pump would this be it.
I check it at the fuel filter housing on the side of the engine. The return fuel line coming from the back of the head connects to this housing, right above the fuel pressure regulator. That regulator has a one-inch bolt head & screws in from the bottom right side of the filter housing as you face it, to help you identify it. They're easy to change yourself, if it ever fails. If you ever remove or replace it, don't overtighten it use 22 ft lbs torque.

Anyway, I unscrew the return line from the top of the filter housing, screw on a brass "T" then re-connect the return line to the top of my "T", then I connect the pressure gauge to the middle of the "T". This tells me the actual fuel pressure running thru the internal engine rail :)

I've only worked on MXS & older Cat's, they're 2004 & 2006 engines. Maybe yours has a "quick-connect" on the housing, that would be nice. I don't have any specific info on the NXS series engine...
arb

Saint Albans, VT

#11 Dec 18, 2012
i have a 2006 truck that sat overnight driver came in and the truc was just running straight black smoke hardly no throttle response or anything replaced harness and all the injectors its a lil better but nothing to ramp and rave about it a cat c15 acert with twin turbos
jay

Dedham, IA

#12 Jan 11, 2013
arb wrote:
i have a 2006 truck that sat overnight driver came in and the truc was just running straight black smoke hardly no throttle response or anything replaced harness and all the injectors its a lil better but nothing to ramp and rave about it a cat c15 acert with twin turbos
sounds like you may have a bad turbo
Kiel

United States

#13 Feb 20, 2013
I have a c 15 cat it just started smoking and running rough it almost feels like it is loading up any ideas
aaron bartemy

Saint Albans, VT

#14 Feb 20, 2013
the problem may be a bad ecm thats what i found to be bad on mine was loading up and no throttle response what so ever

“Cat & Cummins ECM programs”

Since: Jun 12

Marion, IN

#15 Feb 22, 2013
Kiel wrote:
I have a c 15 cat it just started smoking and running rough it almost feels like it is loading up any ideas
I would have the injectors tested before buying or replacing any parts.
Catman3406c16

Haslet, TX

#16 Feb 22, 2013
Kiel wrote:
I have a c 15 cat it just started smoking and running rough it almost feels like it is loading up any ideas
If it just started all of a sudden, it could be as simple as bad fuel. Did u just fuel up? Y/n. Does your truck have a fuel pressure gauge? Y/n if yes , what is press ? Is fuel airated , restricted or leaky fuel suction hose ? Extreme cold climate , water turned to ice in bottom of fuel tank , restricting flow ! This would be simple starting point !
marcus

Australia

#17 Sep 21, 2013
i drive a western star with a c15 acert in it , we,ve replaced injectors , all fuel lines filters , drained an cleaned the tanks . westrac perth have been trying to diagnose {guess} what the problem is for the last month to no avail . it has a miss an runs rough after sitting . i pick it up from workshop and it misses again within 100 km or so . could it be the transfer pump pressure or wiring harness in rocker cover at all

“Cat & Cummins ECM programs”

Since: Jun 12

Marion, IN

#18 Sep 22, 2013
marcus wrote:
i drive a western star with a c15 acert in it , we,ve replaced injectors , all fuel lines filters , drained an cleaned the tanks . westrac perth have been trying to diagnose {guess} what the problem is for the last month to no avail . it has a miss an runs rough after sitting . i pick it up from workshop and it misses again within 100 km or so . could it be the transfer pump pressure or wiring harness in rocker cover at all
Don't you just love the "parts changers" these dealerships employ? They should have checked the fuel pressure AND the transfer pump first!

When the wiring harness inside the head starts to fail, it will cause the "check engine" light to come on, and also store a "fault code" in the ECM. Good luck!
L Jahn

Wellington, Australia

#20 Oct 31, 2013
marcus wrote:
i drive a western star with a c15 acert in it , we,ve replaced injectors , all fuel lines filters , drained an cleaned the tanks . westrac perth have been trying to diagnose {guess} what the problem is for the last month to no avail . it has a miss an runs rough after sitting . i pick it up from workshop and it misses again within 100 km or so . could it be the transfer pump pressure or wiring harness in rocker cover at all
<Marcus, did you find the problem. My husband drives a Western Star 4864 and for the past month it runs very rough on first starting and then intermittently. Had Detroit run a check (of course nothing seems out of order)- my husband has checked fuel tank; did you find a resolution?\
whiplash2000

Butterfield, MO

#21 Nov 30, 2013
changed my boost pressure sensor fixed this problem

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