Mp Engine Code

[cxn613]

Our 2008 cxu mp 8 485 showed a code of mid 128, I forget the rest of the numbers. Looked it up in the book and ended up being #5 injector code. The motor was running rough, but still running. I erased the fault code using my steering column mounted switch. As soon as i did that, the lighting bolt went out and the motor smoothed out. Ran the truck the rest of the day with no problem. Right after I erased the code and started back down the interstate it started a regen right away. What could have been the cause of this fault code????? Thanks

[rhasler]

Our 2008 cxu mp 8 485 showed a code of mid 128, I forget the rest of the numbers. Looked it up in the book and ended up being #5 injector code. The motor was running rough, but still running. I erased the fault code using my steering column mounted switch. As soon as i did that, the lighting bolt went out and the motor smoothed out. Ran the truck the rest of the day with no problem. Right after I erased the code and started back down the interstate it started a regen right away. What could have been the cause of this fault code????? Thanks

Usually low fuel pressure caused by leaking injector cups, but it could be any of the exterior fuel items too.

[Mackpro]

Our 2008 cxu mp 8 485 showed a code of mid 128, I forget the rest of the numbers. Looked it up in the book and ended up being #5 injector code. The motor was running rough, but still running. I erased the fault code using my steering column mounted switch. As soon as i did that, the lighting bolt went out and the motor smoothed out. Ran the truck the rest of the day with no problem. Right after I erased the code and started back down the interstate it started a regen right away. What could have been the cause of this fault code????? Thanks

There is a Mack service bulletin on injector fault codes, dont see many injector failures but mostly the wiring harness connectors at the injectors loose connection. We install new connector ends and this seems to fix the malfunction code most of the time. However as Rasler said the injector cups can cause issues as well. Also check the fuel tank for gasoline! We have had 4 trucks in the last 2 months that had gas in the fuel tanks and 2 were MP's and caused injector codes.

[rhasler]

Also check the fuel tank for gasoline! We have had 4 trucks in the last 2 months that had gas in the fuel tanks and 2 were MP's and caused injector codes.

Was that a mixup at the pump by the fuel supplier or was it sabotage?

[cxn613]

There is a Mack service bulletin on injector fault codes, dont see many injector failures but mostly the wiring harness connectors at the injectors loose connection. We install new connector ends and this seems to fix the malfunction code most of the time. However as Rasler said the injector cups can cause issues as well. Also check the fuel tank for gasoline! We have had 4 trucks in the last 2 months that had gas in the fuel tanks and 2 were MP's and caused injector codes.

We have had the injector cups replaced twice. The first time they replaced the ones they thought was bad. The second time they said the other ones needed replaced that didn't get replaced the first time. That really wasn't a good enough "fix" for us, so we told them to replace them all at one time and we picked up what warranty didn't. What we experienced with that was after the truck would sit overnight, it would crank over more than usual before it would start. So hopefully its maybe just a connector issue.

[Mackpro]

We have had the injector cups replaced twice. The first time they replaced the ones they thought was bad. The second time they said the other ones needed replaced that didn't get replaced the first time. That really wasn't a good enough "fix" for us, so we told them to replace them all at one time and we picked up what warranty didn't. What we experienced with that was after the truck would sit overnight, it would crank over more than usual before it would start. So hopefully its maybe just a connector issue.

On the injector cup issue there are now stainless cups and new style injectors that come in a kit from Mack that will hopefully cure the cup issue. On the gasoline deal, all these trucks were dump trucks that were working in an area far from truckstops, these gas stations would have 4 pump handles on one stand, 3 grades of gas and then diesel. The diesel should have a black cover on the handle/nozzle but we found some stations would have green covers on the handles like the gasoline. The drivers just weren't paying attention.