Isx cm870 boost in and out

[Chamberpains]

Absolutely check that low mount VGT controller. Does this problem happen with the high Jake brakes also? Intermittently not boosting high enough?

The simplest easiest way to check controller function is If you have access to a known good VGT controller off another unit. Swap yours for it for a week and see if the problems go away. Other than that its basically process of elimination. If everything else is good than the controller is one of the last and a bit pricey things to eliminate. If you do have to replace it, don't go to fleebay and some half ass reman site. Buy OEM Holset only. The rest are absolutely garbage. I went through 2 crap remans before going Holset genuine.