Ctp713 Mp7

[Csg]

New to the group.  I bought a 2007 granite just over a year ago and have had an issue with a surge.  Mack dealer told me maybe the turbo after they replaced the actuator with no change.  I can’t see it’s the turbo.  Truck has a slight surge under a load.  It’s rather annoying and is costing me power and fuel I’m sure.  No codes,  I’ve been wondering if it could be egr related.  I’ve also noticed more recently that the oil temp seems to be a lot hotter.  Under a load pulling a hill it’ll easily see 240.  Normal driving with a load 225.  I’ve been trying to see if there is a way to easily disconnect or block off the egr.  Not having much luck.  Any help is appreciated 

[Joey Mack]

EGR is a good call, have you checked fuel pressure? when you say "Surge"  does it pull hard or lay down?

[Joey Mack]

I forgot to welcome you..... There is a boatload of knowledge here... keep in touch...    jojo

[Csg]

I have not check fuel pressure however it seems to do it at all different rpms and throttle positions.  Although at higher rpms it doesn’t seems to do it as much.  I use the word surge but it’s hard to describe.  When your under load,  and when I say load I don’t mean loaded I just mean when the engine is under a load.  You can hear the turbo spool and then not for a second and then spool and die again.  When it does this the rpms fluctuate about 150-200 per the gauge although sometimes it feels like more.  Almost as if you let off the petal some and get back in it.  I guess the turbo vanes could be acting up but I hate to spend that kind of money and cross my fingers.  

[Joey Mack]

are the fuel filters fresh?   What repairs have been done recently?  this may be basic stuff....  since there are no codes,  jojo

[Joey Mack]

i forgot to ask.... manual trans, or Allison?

[Csg]

It’s an Allison.  It seems to do it in any gear and just about at any rpm except real high ones 

[Phoenix disaster relief]

My 07 mp7 manual tran did the same thing until I reached the maxed speed like 78 and then it quit for the rest of the day I ran a boatload of additive/injector cleaner and it's been a while since its done it