Mp8 will not boost

[Mack317]

Have 2013 mp8 chu613.420k miles.been to 7 different shops with 6 different answers.feels like it’s slow on acceleration.pulls hills okay.but my main problem is when you come off full boost at 25-30 psi and drop to 16-20 psi it will not go back on boost. I have to let off pedal for a second and then it will go to full boost.has code for boost pressure. I replaced sensor.also has code for egr differential pressure.shop said it read .31. No smoke.sometimes starts in 1 second sometimes takes 5 seconds.when running empty with steady pedal it will boost 5 seconds then off 5 seconds like a switch is making it surge. Seam to me like electric  issue because it’s steady.

[Joey Mack]

Throttle position sensor??

[fjh]

7 hours ago, Mack317 said:

Have 2013 mp8 chu613.420k miles.been to 7 different shops with 6 different answers.feels like it’s slow on acceleration.pulls hills okay.but my main problem is when you come off full boost at 25-30 psi and drop to 16-20 psi it will not go back on boost. I have to let off pedal for a second and then it will go to full boost.has code for boost pressure. I replaced sensor.also has code for egr differential pressure.shop said it read .31. No smoke.sometimes starts in 1 second sometimes takes 5 seconds.when running empty with steady pedal it will boost 5 seconds then off 5 seconds like a switch is making it surge. Seam to me like electric  issue because it’s steady.

I replaced sensor.also has code for egr differential pressure

Did you clean out the venturie tube when you replaced the Sensor? if the ecu sees low egr flow it will open the EGR valve more and more and the boost will never build correctly also you may have a sticky EGR valve OR turbo! due to, to much soot from the diff sensor issue !

Just an observation!

[Mack317]

Shop did Boost sensor so don’t know if they cleaned it. Sounds like your onto something. Will try that next. Thanks 

[Mack317]

On 4/26/2023 at 7:47 AM, Joey Mack said:

Throttle position sensor??

Yea I thought that to. Volvo had a lot of problems bake in 2008 with those. But 8 year Mack mechanic said he never replaced one. May try that tho. Thanks