CM871 Engine cycle...

[Hammerhead]

(12-22-2016 )Rawze Wrote:  

(12-22-2016 )Rock hound trucking Wrote:  i have the same trouble with my @m*m^2 any boost over 38 psi and i get a a vibraton back out of it and the vibration goes away . how can a guy fix it or what changes have to be made . i pull the mountians lots and like the extra power my pyro runs around 750 when pulling hard with high boost once a back out it it drops down just below 700

Lower the boost levels a bit. It sounds like your making too much boost for the power your making.

With winter temps the air is more dense. This translates into more boost pressure than summer time. If you drove an older truck with a standard fixed vane turbo and a boost gauge I'm sure you noticed that they would always make more boost in the winter, particularly on really cold days.
Watch your boost gauge on a good pull and make a mental note of the rpm range where your boost exceeds 38psi.
Pull the cal from your ECM, in the C_TCG_Min & Max table lower the numbers in the upper range of the table of the rpm range where you were exceeding 38psi by 2 is a good starting point. Then send the file back into the ECM, and make note of boost pressures again. Repeat if necessary. If you're only noticing it exceeding 38psi on really cold, -30 or more days, just feather the throttle on those days.
I've had to do this with winter as well.
*NOTE!!! This is with @M*M^2 that uses controlled VGT closing percentages, NOT a tune that uses the mass air flow and let's the ECM decide the VGT position. If you don't know which version you have, confirm it before doing what I have suggested!