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Andy
Andy, Truck Diagnostic Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 1571
Experience:  International trucks, International, Maxxforce and Cummins engines, diagnostic, electrical, Hvac and refrigeration repairs
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01 Peterbilt 379 w/IXS475 sometimes will surge under heavy

Customer Question

01 Peterbilt 379 w/IXS475 sometimes will surge under heavy load/hard pull/hot weather. Sometimes is the key word, and it must be the combination of those 3 factors for it to misbehave. I have a long list of items I have replaced, but the problem still exists. I"m a single truck owner/operator and can't afford $130.00 an hr. + dyno fees for a shop to attempt replicating the conditions, and I seriously doubt it would do it on a dyno anyway. Need advise, please!
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Andy replied 1 year ago.

Hi my name is ***** ***** i would like to try and help if i can ! Can we start with the engine serial number please ? * digit number on the ECM starts with a 7

Expert:  Andy replied 1 year ago.
Do you still need help ?
Customer: replied 1 year ago.
Engine Serial # ***** ***** am not presently by the truck, but I will attempt to find the ECM # ***** are requesting when I return to it tomorrow
Expert:  Andy replied 1 year ago.
I will find the troubleshooter for this symptom .
Expert:  Andy replied 1 year ago.
https://www.dropbox.com/s/wgcher7l1qsd4is/3666259-t067-tr.pdf?dl=0
Try this link and follow it as best as you can ! Let me know if you need something else.
Customer: replied 1 year ago.
Andy...also noticed today that problem seems to occur when engine oil gets hot. Cummins has advised me that Peterbilt gauges are notoriously inaccurate, and if my reading of 275-300 were accurate, the engine would have shut down. Even so, the gauge is getting close to 300 and at that point, the sporadic loss of power begins. When oil cools back to a displayed temp of 275-285, the engine runs normally. This is the only constant that I can find with the problem occurring. Open to suggestions.
Thanks
Expert:  Andy replied 1 year ago.
Please follow the link as best as possible .
Customer: replied 1 year ago.
Sorry, but the #'s on ECM are no longer legible/visible. Is it possible to work with the engine serial# ***** provided?
Customer: replied 1 year ago.
Well, I followed the link provided, and since I am the owner/driver, I do not own diagnostic software or have a the capability of 'plugging in'....
Customer: replied 1 year ago.
I'm sorry if I wasted your/my time. I thought this forum would assist someone in my situation based upon symptoms. It sounds like you are geared more for assisting actual technitians who are stumped. Is that a fair assumption?
Expert:  Andy replied 1 year ago.
It's ok ! No worries ! I am here to try and help whoever I can . It's what i like to do . If possible , we can use Skype to talk about this further if you want .
Customer: replied 1 year ago.
Had a local mechanic 'plug into' truck, and oil temp issue appears to be nothing more than an inaccurate guage. 40° off at 170° so next step is replacing fuel lines. Appropriate?
Expert:  Andy replied 1 year ago.

Which fuel lines do you want to replace ?

Customer: replied 1 year ago.
I guess I'll replace the lines spplying fuel to engine from fuel tanks along w/line from lift pump to fuel pump. Not sure how old they are (possibly 15 yrs) and I've been told they degrade/colapse inside. I've actually experienced this on other trucks
Expert:  Andy replied 1 year ago.

Ok That is a good possibility . Especially if they are braided hose

Customer: replied 1 year ago.
They are. Will get this done tomorrow and load the trailer. Having unusally cool weather here the next few days (Oklahoma) so the real test will be when the outside temp. exceeds 90 again. Will keep u posted. If problem still remains, I may be stuck with having it strapped to a dyno and trying to duplicate issue while being monitored. That's what I'm trying to avoid.....big $$
Expert:  Andy replied 1 year ago.

We can keep tackling it till the problem is resolved

Customer: replied 1 year ago.
OK. Thanks
Expert:  Andy replied 1 year ago.

Have a good evening !

Expert:  Andy replied 1 year ago.
Hi there ! Just looking for an update ! I see the question is still open . Do you need further assistance ! Let me know !
Please do not forget to rate my service to you ! Feedback is important and bonus is appreciated . Thank you .
Customer: replied 1 year ago.
I give up. Replaced all fuel lines. Did great for 24 hrs. As of 30 min ago, it's barely running. Praying for it to catch on fire
Expert:  Andy replied 1 year ago.
Ok so do we believe there is air getting into the suction side of the pump ?
Customer: replied 1 year ago.
Not a clue. Not going to risk stopping until I get to receiver 90 miles from here. Here's a clue.....rougher the road, rougher it runs
Customer: replied 1 year ago.
Max manifold pressure 18 and fluctuating wildly
Expert:  Andy replied 1 year ago.
Ok this definitely sounds like a wiring issue ! Because the rougher the road , the more wiring will bounce around ! You should try running it at a higher rpm in fast idle ,parked , and then wiggle the entire harness everywhere that you can see wiring while it is at a higher rpm and listen for any changes in sound from the engine while doing this . If there is change while you are wiggling in a specific area , then that will be where your problem is !
If that is all good , then perhaps we are looking at a faulty temp sensor somewhere giving the ECM the wrong info , therefore the ECM is calculating based on that info and either overfueling or underfueling. We need to try and do a cold soak check . This is done by leaving the truck alone for a few hours and let it cool down to ambient temp outside , then connecting with a scanner or software and a laptop (insite program preferrably ) and checking all the temperature sensors at that time . They should all be reading very close to ambient temperature in your are at that time . Also the pressure sensors should be reading zero psi . This is all checked with the key on and engine off .
Customer: replied 1 year ago.
It will have to go to shop. I've exhausted my capabilites, patience and resources on this thing. As soon as it's running, I'm getting rid of it. I can't use a truck that has let me down as much a s this one has.
Expert:  Andy replied 1 year ago.
Before giving up , I would please try setting the engine at 1500 rpm , and at least do the wiggle test while its running ! Going by what you just described , you will very likely find the problem this way .
Customer: replied 1 year ago.
Will let you know. Should be at delivery point in 1.5 hrs (if it makes it there)
Customer: replied 1 year ago.
This may sound far-fetched, but while inside getting coffee this morning, there was a lightning strike on the property. Possible this could have affected electronics? It sure knocked out everything at the store
Expert:  Andy replied 1 year ago.
Ok! Like I said ! Set rpm to about 1500 RPM , then open hood and grab harness and wiggle and twist it anywhere you see wiring particularly loose and not properly secure, especially over the valve cover ( common area for trouble in harness) wiggle and twist inch per inch at a time while listening to any changes in engine while running . Wherever it acts up while wiggling is where your problem will be . Also follow and shake the ECM clean power feed harness which starts from the batteries and goes all the way to the ECM . This is another common problem.
Expert:  Andy replied 1 year ago.
As far as the lightning , I am going to say no ! Not unless it hit it directly . The truck is all sitting on rubber so we should be good there .
Customer: replied 1 year ago.
Just wondering. Had a Freightliner with a close strike and lost ecm and most guages
Expert:  Andy replied 1 year ago.
Unless it had contact with the ground somehow I don't think it was related . I am told rubber insulates from lightning strikes unless directly struck by lightning . Check for codes to be sure .
Customer: replied 1 year ago.
Getting gray smoke as it is missing...normal?
Expert:  Andy replied 1 year ago.

Yes this would be raw unburnt fuel . Is this happening while wiggling harness ?

Expert:  Andy replied 1 year ago.

If you are seeing anything happening that changes while wiggling harnesses , anything at all , then that indicates that the problem is right where you are shaking the harness at that time .

Customer: replied 1 year ago.
I went to 1500 rpm and wiggled everything, and it didn't change. It's r i nning worse by the minute
Expert:  Andy replied 1 year ago.

Have you wiggled and inspected the clean power feed harness from the batteries ? This is the smaller harness leaving the batteries . That is where the ECM grabs its power

Customer: replied 1 year ago.
Nothing changes
Customer: replied 1 year ago.
Barely running.
Expert:  Andy replied 1 year ago.

I feel you're problem is related to the wiring somewhere for sure

Expert:  Andy replied 1 year ago.

Please turn the engine off , disconnect the smaller 4 pin connector on the ECM and check for damage .

Expert:  Andy replied 1 year ago.

I f no damage is found , please load the power and ground at that connector using a headlamp with both beams .

If light comes on bright and remains bright for 30 seconds lighting up both beams , then the circuits from the batteries are likely ok .

Customer: replied 1 year ago.
I have to nurse it 8 miles to be at destination and safely off road
Expert:  Andy replied 1 year ago.

Ok I have to run an errand! Be back in awhile !

Customer: replied 1 year ago.
Unloaded and headed over to the only fuel stop in this little town d o ic it doesn't restart, I'm not in the way
Expert:  Andy replied 1 year ago.

ok sound good ! I will check in once in a while for updates .

Customer: replied 1 year ago.
What exactly do I need to unplug?
Customer: replied 1 year ago.
Turned it off for 30 mins., started toward home. Better (for now) but still not right by any means
Customer: replied 1 year ago.
The farther I go, the worse it gets. Trying to limp it to OKC (225 miles)
Expert:  Andy replied 1 year ago.

Please give me the engine serial number

Expert:  Andy replied 1 year ago.

It is an 8 digit number on the valve cover label or on the ECM label .

Customer: replied 1 year ago.
14016438
Expert:  Andy replied 1 year ago.

Thanks

Expert:  Andy replied 1 year ago.

ok On this one , it will be the first connector closest to the front of the engine .

Customer: replied 1 year ago.
OK. It's likely going to force me to stop somewhere along the way. I will let u know when that happens. Would like to keep it rolling while I can
Expert:  Andy replied 1 year ago.

Once unplugged , you should load test using a small headlamp from pin 38 to pin 29 with the key on . This is your ignition power .

Expert:  Andy replied 1 year ago.

If you want to continue this using skype we can have an audio conversation and get through this .

Are you at a garage where you can work on this ?

Customer: replied 1 year ago.
No. I am in the middle of west Texas doing everything I can to limp this thing back to civilization
Expert:  Andy replied 1 year ago.

Ok then ! Try disconnecting and reseating this connector and all the power connectors for the ECM harness from the batteries to the ECM . Anything you see that comes apart along the way should be inspected and reseated . If you see any damage along the way , repair it as best as you can in the conditions you are in.

Customer: replied 1 year ago.
I will do that if/when I stop. Can't take ANY chances on this thing being stranded out here
Expert:  Andy replied 1 year ago.

Then you should probably continue til you get to a garage

Expert:  Andy replied 1 year ago.

I can't help you till you are ready to troubleshoot this.

Customer: replied 1 year ago.
Had to stop twice now. Each time, after turning the engine off for about 5 mins. When I st a rt it up with it runs great for afew miles, then starts surging again
Expert:  Andy replied 1 year ago.
Yup this is electrical for sure .
Customer: replied 1 year ago.
Agreed. Strange that it 'resets' so quickly. Switched it off/on 4 times now
Expert:  Andy replied 1 year ago.
but probably because the weak connection is getting worse .

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