01 E7 popping after idling

[mechmagcn]

Hey all, long time since I've been around here.

 A friend called with problems. 01 E7 460 after idling will pop through the exhaust  when taking off from a stop. Sputters and occasionally backfires. This happens through 4th or 5th gear and then clears up. It won't do it again until it idles for some time, usually while getting loaded.

 Another friend, a rather good mechanic has pulled his hair out trying to figure this one out. 

 My thoughts were low fuel pressure or sucking air, but he has pretty much ruled those out. Fuel lines have been changed, timing sensors checked, fuel pump changed, injectors tested bad and replaced, engine wiring harness had some wear so replaced, he even bought one E-up and swapped holes to see if that was it. I'm sure there's a few other things that he's tried that I'm forgetting. 

I'm a retired truck and heavy equipment mechanic that used to work on this truck, but seldom turn wrenches anymore. Just trying to get some insight into this problem. 

 I never was one to throw parts at a problem and hope something would stick. I'm afraid the mechanic working on it has given up and that's what is happening now.

 I hope someone has seen this and can help a broke down old mechanic out. Thanks all.

[Joey Mack]

several things come to mind,      valve adjustment??      Engine brake (if equipped) hanging up??   

[mechmagcn]

Thanks for the response. Valve adjustment checked, no engine brake. 

[fjh]

Long shot here!  what model of truck is it? Ch CV ? If its a CV Go to the primary fuel filter and remove the elbow from the primary side of the fuel filter Several times  We have found debris in that elbow  ,we recently had one with a piece of a rag in there lines were all clear ! The indicator for this was similar symptoms checked with a gauge wacky fuel pressure ! the fuel transfer pump gear can come loose on the shaft as well also ! Just a couple of real odd places to look! There is a possibility you have a displaced H ring and a lifter hanging up or a sticky valve stem You would have  likely have seen a bent push rod while doing your valve set thou! Note this unit we had also had an engine brake so accompanied by the the popping was blu white smoke it had electrical issues as well there, so its difficult to predict if this is your issue or not!  

 

Good luck

Edited June 2, 2021 by fjh

[Vmac3]

The primary and secondary fuel pressures should be checked first. 4inhg on the suction side and around 70 psi on the secondary side. I also had several units where the guide pin for the EUP roller broke off and caused an engine miss. 

V

 

[Joey Mack]

Has this engine been over-revved? I know..... Dumb Q because no driver will admit it, however, a bent valve can do this.. of course we need to look at the simple things first.   I use an inferred temp. gun often to help point to a bad cylinder.  It's not fool proof, but if you see a large difference in cyl. temps on the exhaust manifold, high or low,, you can find the cyl. to look closely at..  yes 3+4 will be hotter, but .... anyway... you get it... jojo

[theakerstwo]

Dont forget that these engine can get a bad injector that will hang in full fuel with out the injector harness connected.They can sound like a miss but will be over fueling that cyl.You can loosen that line and make it sound better but in reality its missing.The temp gun can tell you alot.The engines that i found this on would only do it when their hot.On engine i had would still try to run with the turned off.This dont sound to be the trouble but dont forget.

[wilbur]

Does it only do it when its hot and humid out?  Mine did the same and they put a new file in it called a Smoke file, but the mileage got so bad I had them put the old file back in it

 

[mechmagcn]

Sorry guys, been too busy to check back in. 

 As I said, I'm not the one doing the actual work, just trying to help a friend and former customer. 

The truck is a CH613.

The truck will not do this just revving the engine, it only does it when taking off and usually clears up by the time you hit the high side.  With this said, not sure how much an ir thermo would help. 

All fuel lines have been checked, the elbow in question has been pulled and resealed. E-ups have been pulled and a reman swapped hole to hole with no change. 

 From the looks of it I'm going to have to come out of retirement and get my hands dirty to figure this one out. 

Thanks for the replies, I'll be sure to let everyone know what we find.

Edited June 7, 2021 by mechmagcn

[Joey Mack]

Come out of retirement.......  It's a different world in the shops now.... Too many laptops and not enough diagnostics with, eye's, ear's, hand's, smell, and of course.... good Old Know-How......   Jojo

[theakerstwo]

1 hour ago, Joey Mack said:

Come out of retirement.......  It's a different world in the shops now.... Too many laptops and not enough diagnostics with, eye's, ear's, hand's, smell, and of course.... good Old Know-How......   Jojo

Joey back when i was still working a man brings his older freightliner in the shop for a problem but the tech that draws the job did not know the cab had been changed to a from a newer truck.The tech had over a hour standing there looking at his laptop that was connected to a dead diag plug that was dead and not connected to anything.I was not there but some say he got around to raising the hood to find a old cummins under there.

[Joey Mack]

Good story Glenn... 4 years ago.... I watched my co-worker, A Mack Tech......  pull the laptop up to the truck, to see why the ....  headlights didn't work....   🙃

[mechmagcn]

Really wish I could come out of retirement, the money was so much better when I was self-employed. But a broken down body and severe arthritis from being a field mechanic for 30 years keeps me stuck at a desk job now, watching others keep up maintenance in a small State Park.

Damned kids now days don't have a clue on how to troubleshoot, plug the laptop in and start throwing parts at it.

[mrsmackpaul]

Is it possible for oil to be building up in the exhaust somehow when sitting just idling, and then with the heat from the exhaust it ignites when under load

Not a lot of heat is generated out the exhaust until it is under load and might take few seconds to make enough heat to ignite 

I really have no idea at all

 

Paul

[fjh]

12 hours ago, Joey Mack said:

Come out of retirement.......  It's a different world in the shops now.... Too many laptops and not enough diagnostics with, eye's, ear's, hand's, smell, and of course.... good Old Know-How......   Jojo

Joe Unfortunately the diagnostics on todays units  Rely on computers  almost totally!  Because they took all of our other senses away, no smoke to read , nothing to smell the normal  noises we are mostly used to are all  covered up by the after treatment Garb! Your blind!   you are forced to believe what the screen tells ya! You can rely on past experience and the computer screen with this stuff And some times it comes down to parts Cannoning because your at wits end With dollar store sensors ect ! Guessing game!

[Joey Mack]

I know......  You are correct...  I just correctly diagnosed a noise in an 04 aset, last week..  I told the owner (who is also a good mechanic) that the noise was likely a bad lifter. told him to drop the pan and look up....... #1 exh. lobe is junk..... I pulled the cam yesterday.  No laptop needed for this one... anyway, I hate it for the owner's of these truck's, who have so much downtime lately, due to poor diagnostics, parts cannoning, and lack of MECHANICAL knowledge... Ok, I'm done now....  I look forward to learn what fixes this issue... Jojo

[mechmagcn]

Hey guys, just stopping by for an update. Turns out that he had another identical truck start doing the same thing, just not quite as bad.

They buy fuel in bulk, 6-8 thousand gallons at a time. Fuel ran low at the yard, so the driver of the worst truck started getting fuel at a nearby truck stop and the problem went away within a day. Same thing with the other truck when they filled it at the truck stop. Took about 4-5 days for the supplier to fill the tanks at the yard and within two days both trucks are popping again. I've told them to locate a lab to check the fuel. 

He called last night and said one of his contract trucks had started doing the same thing after getting a tank of fuel from his pumps. 

Any ideas on this? Bad fuel mixture? Low or high cetane?

My wife works for another logging contractor and said he bought 15,000 gallons of fuel last week at a lower price because it was left over winter blend, any possibility that this is the fuel problem that my friend is having?