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2011 MP7 low power


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I’ve got a 2011 Mack with an MP7 in the shop with a rough idle, jumping between 600 and 650 RPM and low power. Truck has no fault codes. It’s gotten a new EGR pressure sensor, EGR valve, Fuel pressure relief valve, fuel filters. EGR cooler was clean when checked. Removed and checked for debris in fuel lines going to ECM cooling plate. Fuel pressure jumps around between 50 and 60 PSI at idle.
No air bubbles in return line going back to tank.

Any ideas?


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5 minutes ago, Joey Mack said:

are you having issues with the power steering as well?   jojo

Good call Joey, how many miles are on the truck, what kind of truck is it, and anything previously done to it before this started?

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I dont want to jump too far ahead, but I have fixed this issue a few times...    you reckon this has caused an issue, and the drive ends are worn out between the tandem pumps?  jojo


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It’s actually a 2012 not 2011. GU713 roll off truck, 296000 miles on it. Power steering works fine. I’m using Tech tool. I’ll pull the gear out and check it. The truck originally came in requesting a regen with no fault codes. That’s when I put the EGR valve on because it wouldn’t get up to temperature. It regened after that.

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  • 2 months later...

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