2006 KW t800 isx15 CM870 power loss

[ahrenb]

Where to start? I searched through and didn't find anything that sounded similar to my issue so I'm here to share and maybe someone has an idea that can help out.

Our oldest truck in our fleet is a 2006 KW with the isx15 cm870. When she is running, she's a workhorse, the driver loves her.

A few months ago, it started dying intermittently. At any sort of time, happened under a load on the highway at speed, happened sitting at the red light in regular traffic. Truck would just shut down out of nowhere. Check engine light would pop on but the only code would be "Power lost with ignition on" I thought I had it traced down to some bad battery cut-off switches. Changed them out with new and replaced the jumper wires on the batteries and the thing ran great for a few weeks. Came in for a service and found the charge air was bad, along with a slew of other minor issues.

We sent it out to our other location to repair as they had more room and time. It came back with the "all clear" from our other location. It had been used by a different driver when it was there for about a week and he reported no issues. The very first day that my driver was in it, he got about a half hour out and called me and said, "I just lost all of my power and am sitting on the shoulder of the offramp. Wait, it just died." So I went down there, computer in hand, and the only code it offered me, "Power lost with ignition on"

When this happens, it has a really hard time starting. Just seems to crank forever. I monitored the fuel pressure at key-on/engine-off and the rail pressure was about 20psi, when I got it running, rail pressure was in the neighborhood of 225-240.

We towed it back on one of our trailers and I just got hooked up to it again today. Started right up. Seems to idle a little low, around 550-600, which makes it seem like its running really rough. I warmed her up to 175*F and performed a cylinder cutout test, performed an injector test, performed egr valve and turbo actuator test, performed a cylinder contribution test. Everything came back fine.

I have to admit I'm at a loss. I'm of this newer generation of mechanics and if the computer isn't telling me what's wrong, I have a hard time diagnosing the issue. Any help would be much appreciated.

-Ahren

[Zhidden]

When it dies wack the ecm with something a few times. Sounds like it's kicking the bucket.

They will do weird stuff when going out. Gauges going everywhere, running funny, random shutoff, random codes etc.

Obviously verify power to all pins is good and stable with good wiring.

[Rawze]

First of all, it should be more than 20 psi fuel pressure while cranking. It should be above 50-psi or more.

- The fuel shut-off solenoid, as it starts to go bad, is notorious for making the problem your describing.


- Next, it could also be the ecm if it is more than 8+ years old. Those ecm's are notorious for getting intermittent on the CM870 and CM871 engines. Like Zhidden mentioned about whacking the ecm, Here is more on that...
http://rawze.com/forums/showthread.php?t...0#pid12320

Also, if it is an older model KW... They have this issue too...
http://rawze.com/forums/showthread.php?t...05#pid3505

[ahrenb]

(05-17-2021 )Zhidden Wrote:  When it dies wack the ecm with something a few times. Sounds like it's kicking the bucket.

They will do weird stuff when going out. Gauges going everywhere, running funny, random shutoff, random codes etc.

Obviously verify power to all pins is good and stable with good wiring.

I did notice during my warm up period that the coolant gauge reads about 60 degrees colder than the ecm says it is per insite. Also the oil temp gauge doesn't read anything at all. I will run it for a while today and see if I can't get it to shut down again.

As far as what you replied Rawze, I will look in to this. I can't get a fuel pressure when cranking because of the lag in communication between the ecm and the laptop. I swear this truck "talks" to my laptop so much slower than any other truck in our fleet. The ecm, as far as I am aware is the factory ecm from 2006 so its definitely old.

[ahrenb]

Well, its been outside idling for about an hour now and it hasn't shut down. I tried the tapping of the ecm where Rawze described it in the post that he linked and it didn't affect anything. I am going to do some reading about the fuel shut-off solenoid and look in to that.

[ahrenb]

Took the truck for a 30 mile roundtrip road test. I had insite hooked up with engine and sensor parameters recording. No issues during the road test at all. Fuel Shutoff Valve stayed open the whole time, fuel pressure minimum was 253.6, maximum was 285.7.

The route included stop and go, highway speed, and pulled a 4.5% grade hill for a mile. Hauled a lowboy 3 axle behind me for weight.

The only things that really stand out is my battery voltage had a range of 13.3-13.75 which seems a little low to me but it didn't drop out.

I'm just stumped. I'll try adding the data monitor printout here.
  IMG_0001.pdf (Size: 72.76 KB / Downloads: 159)

[Waterloo]

This just screams ECM failure to me... Is the ECM the original one that came on the truck? It is rare for one to go much over one million miles or extended years.

[ahrenb]

Truck has approximately 650,000 on it. The badging on the ecm shows the same esn that the original truck information from Kenworth shows and I know it hasn't been replaced in my tenure here which goes back to 2014. Only issue I run in to is it being the oldest in the fleet, I don't have another ecm hanging around to swap out for testing.

Either way, dispatch pulled rank and are sending the truck out today, "Don't worry, its only local." so I will likely be called out on a roadcall today. Thanks dispatch /sarcasm.

[ahrenb]

Well, she ran for 2 weeks with no issues. As I was pulling in to work this morning, my driver called me and said, "It's doing it again." Luckily, he was still in the yard and I was able to go back and check it out without being on the side of the road.

When I turned the key over, the overhead warning lights were as follows: Check engine light blinking, water in fuel blinking, low coolant blinking. Low air was on solid, as was engine fan (but that one is always on solid, even though the fan works properly.)

So, I keyed the ignition off and back on a few times. After about 10 times, the lights didn't blink, and as the truck did its abs cycle, all of the lights that are meant to turn off did. I was able to start it and it fired up. Truck ran for about 30 seconds and then shut off with those lights blinking again.

So I shut the key off, hopped out and gently, but firmly, smacked the top of the ecm a few times with the handle of my hammer. Hopped back in and keyed it on, lights were on solid, then went out as they should, truck started right up no issue and kept running. I tried smacking the ecm when it was running to see if it would shut off but it didn't.

Calling to get a price on an ecm.