Boosting for no reason

[Lostfarmboy]

I am new to rawze.com. I just purchased a 2010 Pete 386 with a isx 871. I did the egr tune-up and set the overhead before putting it to work but now it is boosting to 20ish pounds when a small amount of throttle is applied at lower rpms. If I let off it then get into it again it doesn't do it. I'm confused.

[marek4792]

Sounds like your turbo, actuator, and/ or EGR valve could be hanging up and then closing too much. Does the truck feel under-powered for a moment then "wake up" after a few seconds of holding the pedal down?

[Lostfarmboy]

I haven't held the pedal for a few seconds. When it happens I can hear the turbo spooling up and can't really think of any good reason to let it keep happening.

[Lostfarmboy]

It kind of feels like somebody threw the anchor out.

[marek4792]

Are your sensors all new? IMAP, Exhaust Pressure, EGR Differential pressure sensors? I asked because I had a CM870 with the air powered VGT and it would build 35+lb's of boost with my foot barely on the pedal and then the next time would be okay. While the boost would spike under load, the engine would choke itself out and slow you down blowing a big cloud of black smoke behind you in the process. If you hold the pedal too long the turbo will "chuff" violently until you back off the pedal. Granted a CM870 is a different animal then the 871, but it definitely is turbo/egr related especially if it does it intermittently.

[Lostfarmboy]

I replaced the sensors as suggested for the egr tune. Usually it's comforting to know what you have. It doesn't seem to do this if the tevs are kept up but if they get down around 1200 it will do it every time I ease back into the pedal

[Lostfarmboy]

It's exactly like you said yours was minus the black smoke.

[marek4792]

(11-27-2018 )Lostfarmboy Wrote:  It's exactly like you said yours was minus the black smoke.

that's because the DPF is probably catching it, only way to check is to unclamp the pipe behind the turbo and move it aside and drive it around the block while riding the brake to simulate a load and see if it smokes like mad, replace the gasket to the pipe if you do this.. But either way you should get insite and an inline 5 off eBay for around $500 or so, so you can check for faults relating to turbo/ egr and you will need it to recalibrate the turbo and actuator if you end up replacing them..

[Lostfarmboy]

I have insite and inline 6 but there are no faults to chase. The turbo was replaced by the po within the last 6 months don't know about the actuator.