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Daniel Wilson
Daniel Wilson,
Category: Medium and Heavy Trucks
Satisfied Customers: 5437
Experience:  Owner at DJ Wilson
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2012 Peterbilt - 367 Mileage - 240,000 VIN - last 7 -

Customer Question

2012 Peterbilt - 367
Mileage - 240,000
VIN - last 7 - DD167506
ESN - 79560702
Cummins ISX15
Truck is experiencing stumble at 1100rpm - 1300rpm. Will smooth out above that or feels like it is smoother. No faults on dash. No exhaust smoke at all. PM performed. All filters replaced. All connectors across engine checked. Mass Airflow sensor cleaned and replaced. EGR removed and inspected only soot visible on any surface. Was not checked for operation. Repair involved removal of injectors to remove coolant/fuel that hydro locked the engine. 20oz coolant/fuel removed from all 6 cylinders before engine would crank all the way around. Engine hydro locked after it was parked after noticeable white/gray smoke from stack. Engine was shut off twice and restarted with same white/gray smoke observed. 3rd time tried to start and engine only turned over about 90 degrees and no further. Hand turned the engine over several times 360 degrees of rotation observing the same difficulties at same place on crank. Pulled EGR cross pipe to intake manifold and confirmed some coolant on floor of intake. Coolant reservoir was empty. No coolant on ground. EGR Cooler removed. All gaskets and O rings replaced.
Truck bobtail, driving around runs fine except in that rpm range. Very light throttle and it almost feels like a tire with a bubble in it, and at low speeds 15mph-20mph going up thru 1300rpm it is a very pronounced miss which lessons with heavy throttle. Was wondering if the injector wiring harness which has two wires to each of the injectors if they can be mixed in there installation? [white wire to left side of injector terminal and green wire to right side...] example there. Does that matter which goes to what side? Asking because I will check and remove valve cover to confirm. This engine doesn't have an injector cam. Coolant reservoir is full, no bubbles in it. Oil isn't contaminated. Did notice the dash readout on the current fuel MPG being at 11mpg bobtailing from shop getting muffler welded. bobtailing around since its reporting only 7 - 8mpg. I also saw a intermittent problem with the miss when I bobtailed to have the rear drive tires replaced over at the tire shop. I drove the truck at about 18mph and 1200rpm to 1300rpm in 6th gear and held it at that speed for about 1/2mile. Miss did go away and engine smoothed out a few times in bursts of about 3seconds but now it doesn't want to do that on another attempt to do it yesterday. Ill stop here.. I could keep writing forever...
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Daniel Wilson replied 1 year ago.

Hi Christopher, My name is***** you still loosing coolant and have white smoke or has all that been fixed and you just have a stumble? Any fault codes?

Customer: replied 1 year ago.
all that has been fixed not loosing coolant. regen is working fine. no smoke at all. just the stumble and no codes on dash
Expert:  Daniel Wilson replied 1 year ago.

thanks for the update. Monitor your fuel pressure and install a clear hose to see if there are any air bubbles indicating you are sucking in air. If it checks ok and the EGR system tests good, the turbo and actuator are good, the problem is likely a faulty injector with a mechanical problem or damaged injector o ring.

Expert:  Daniel Wilson replied 1 year ago.

Have them tested with Cummins Insite...

Customer: replied 1 year ago.
Install clear hose to monitor for air bubbles where?
Expert:  Daniel Wilson replied 1 year ago.

Between the tank and pump on the suction side..... Then also on the return

Customer: replied 1 year ago.
new injector o rings were installed along with new orings on the fuel crossfeed tubes. what I'm concerned about is if the injector wiring harness if the 2 wires going to each injector if they are supposed to be specifically installed on the injector. left post this color wire right post on injector this color? would reversal of the wires make any difference?
Expert:  Daniel Wilson replied 1 year ago.

The connectors only go one way unless someone played with the harness however it shouldn't matter which way. I do not believe they are marked either.

Customer: replied 1 year ago.
the isx 15 cm2250 doesn't have fuel and timing actuators? you know the 4 small square parts on drivers side of block with 2 controlling the first 3 injectors and the other 2 controlling the last 3 injectors.
Expert:  Daniel Wilson replied 1 year ago.

That is correct. The older ISX's have 2 fueling and 2 metering actuators with the fuel shut off in the middle. Your ISX15 does not have this setup. Where are you with this currently?

Customer: replied 1 year ago.
Still working out how to install clear hose to pump suction and return lines to check for bubbles. Will be looking at EGR valve today...
Customer: replied 1 year ago.
Also will an injector cutout test indicate which injector might be the problem or is that not such a reliably good indicator test?
Expert:  Daniel Wilson replied 1 year ago.

The ISX15 is common rail but I would have an injector test and a cylinder performance test done with Cummins Insite connected. Cummins Insite is the best troubleshooting tool to use on the ISX 15 as well as some specialty fuel system test tools for the fuel system but a large number of tests can be run through Insite. Do you have access to Insite?

Customer: replied 1 year ago.
I have debated getting the connectors and myself, but sadly no. A shop in town I use does and I talked with the tech that had it and have waited to see if I discovered something first then go to them with specific procedures to run on Insight that would hopefully confirm a diagnosis. I am currently cleaning the after treatment muffler. It was looking pretty good some blockage using piano wire down all the passages and blowing it out... So I don't have to worry if it's that....
Expert:  Daniel Wilson replied 1 year ago.

Tanks for the update. Most commonly it would be fuel related or EGR system related. Check for a soot or carboned up EGR system. Clean out the piping, etc. Then monitor fuel pressure and boost to see what they are both doing when this happens... If all ok and after the EGR cleanout I would do a regen and then see if the symptoms come back. If so I am leaning towards injector troubles.