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Another EUP Problem

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What would you do?

1M2AG11C65M029481 2005 CV713

I paid to have HP increased last year from 350 to 400, truck is still a dog still and the motor acts like it has an old quadrajet carb, stumbles and then pulls out of it. 

Idles, starts and runs fine except when crowding it especially noticeable under load, but it pulls out of it.  I have change filters 3 days ago with no improvement. 

History of 8-6 FMI 8 & 8-5 FMI 8 nothin recent but until 2 days ago no active faults but has thrown 8-5 FMI 8 everyday

I checked for wiring issues and cleaned all terminals cleared code took about 30 minutes and the 8-5 FMI 8 popped back up.

I bought a Mack EUP and injector line and bolts today

What do I need to look for especially since it is one of the ones that is hard to get to


"I reject your reality and substitute my own."


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If they changed the horsepower it must be running the latest file? Surprised that didn’t help the smoke stumble issues. Did you tell them about the stumble issues?

if it’s the “hardest to get at” its probably #6. Mackpro once pointed it out, and I believe it to be true, the heat shield is the only thing saving 6 from repeat premature deaths. It’s the hot zone. Are your shields on?  Radiant heat exposure is a killer. Months back I grabbed an engine harness on our 2011 Liehberr and it shattered like glass. It became a big copper furball. I cut back into the heat shielded area and it was still soft and pliable. All exposed spots where radiance could absorb into the wiring were shot.

A number of guys in here have had harness issues in the harness branch that services the EUPs. Getting to be some old rubber on those wires and also exposed to heat if no covers. 

Edited by Mack Technician
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Heat shields are on, i disconnected the wires and cleaned the terminals driver said that on his last load the code disappeared and truck ran awesome and then it came back on when he fueled .  When he pulled it in it was on, he shut it off and a little while latter when I went to check the blink code it was cleared.

I think I may change the #6 with one of the others while I have everything apart so if it is heat related I don't have to do it again.  Or see if I can afford another one from Mack or just leave it and see what happens.

The mack dealer tech when I asked about the stumble said no active codes so everything is working good, asked about the hesitation he said it is supposed to have a hesitation because its an electrictronic engine I didn't argue as it didn't have any active faults and ran good other then that hesitation brought on by the acceleration under load.


"I reject your reality and substitute my own."


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  • 2 weeks later...

Years ago we had customers that had the same issues, mostly heavy duty oil field application. The truck felt like something was holding it back then it would start to pull ok or drop out in high upper rpm's. Our forman would call Mack tech support and explain issue, they would usually tell us to flash both eecu and vecu, DO NOT save customer parameters and program w/new datafiles. I would print out customer parameters and manually enter them back. I think it was called heavy haul file or something like that. Been a while and slept since then. 

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