Let me say I know these engines have a bad rep..but I will stand here today and tell you this is my first issue with this truck and it's been the best truck I've owned so far ...just had to put that out there even though it's only 500k miles it hasn't had a single issue ...until now
So the problem now I will keep it short for you..truck builds boost about 40psi and then instantly drops off to 0 and bounces right back up to 30ish psi (bobtail) I have no codes and no other issues but I feel the loss of power ..it does have the updated acv but it's been on the truck since factory year is 2014...this issue happened every time and sometimes it will only hit 30 psi ...pinched off the waste gate ..no change checked for leaks ...nothing keep in mind it is hitting 40psi just drops as soon as then comes up 10psi lower I can't figure it out. Any help would be appreciated my next guess was air control valve but we know they are expensive and I don't want to throw parts at it.
Maxxforce 13 boost pressure issue
Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by tipto3, Jan 18, 2025.
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The manual does say the valve inside the turbo can be manually pushed opened by the boost pressure as a fail safe in case the ACV or actuator fails. I have never come across this, but I wonder if the return spring is weak or broken in the actuator making the push rod have reduced closing pressure on it and boost pressure itself is pushing open the waste gate valve to cause the boost dump?
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I am thinking the valve inside the turbo is getting pushed open. When you pinch the line at the actuator, air comes from the ACV, not the intake manifold. Once you pinch the line, the actuator is no longer able to dump boost. If you had a major boost leak, it would make loud pop or squeal noise, so I don't think that is it either. If the flap valve is getting pushed open inside the turbo, you need to hold it closed. Force the wastegate rod from moving by jamming it with vice grips or something to see if the boost drops or not. If it does, then something external is doing it and we can look again for a boost leak. If it holds pressure and boost, then I think the return spring in the actuator is weak or broken.
little cat 500 Thanks this. -
Heavyd Thanks this.
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