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Weird boost problem in high RPMs

abracadabra

Member
Joined
Jun 1, 2025
Messages
9
I have a 2008 UD 1400 with the Hino engine that keeps decreasing boost after revving past 2500 RPM. The CEL appears, the boost disappears, and it drives like trash until I kill the ignition and restart. For a short time it's gonna run smooth, then it repeats unprecedentedly or what. I want this issue resolved soon... I know my bike is old but I don't deserve the stress coz I'm old too. LOL.
 
Sounds like a boost leak or failing turbo sensor, it could be MAP or VGT actuator, you can scan for codes first. You're not too old for smooth power, man. Let's fix it!
 
What have you checked so far, any scan tool readings or signs of a faulty MAP sensor, EGR valve, or turbo actuator acting up when the boost drops?
 
it could be MAP or VGT actuator,
I agree, those two are classic culprits for that exact issue on a diesel. and yeah, before anything else, OP has to get the DTC codes pulled. That Check Engine Light isn't just for show, it's telling us exactly why it's going into limp mode. That's gonna be the first best clue
 
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