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berrytrucking94 · 08-03-2019, **(Subject: CM870 Turbo Issue )**

Hey guys I hav an 06 six cm870 motor, tuned well by a member here. tried searching threads but couldn’t find any with the exact symptoms I’m having but I’m sure I missed a few

turbo acting very temperamental, mostly happens when under load. I’ll be pulling a hill for example and downshift but as I go to give it throttle it’ll spool normally for a few seconds and then sound like it’s spooling half assed and the egt will spike high very fast 1000-1100° within a few seconds.. Excess black smoke, loss of power. If I take it out of gear and let all boost drop then get it back into gear it’ll act normal for a short while until the next pull. Also does this if I hit the engine brake and ease back into the throttle..turbo just sounds wrong

Checked for boost leaks, truck still pushes 38-39psi no problem. Did actuator test and turbo speed test on insite multiple times and both passed. No leaks from air control valve, no oil in turbo and hardly any play in the wheel. No codes either

Any ideas/ suggestions are appreciated!

Lonestar10 · 08-03-2019, **(Subject: CM870 Turbo Issue )**

check for travel on the arm that moves the vgt i beleive put about its either 60 or 90PSI to it and i think the measurement is 12MM is how far the valve should move make sure it moves slowly it could be binding some then suddenly lurching closing to far.

Chamberpains · 08-04-2019, **(Subject: CM870 Turbo Issue )**

Does the boost drop out during these occasions? If it does, and since it affects both boost and jakes, then it points towards a faulty actuator control module intermittently dropping out. It will not throw a CEL. But before you spend the $$ on a $900 Holset module (DO NOT BUY REMAN FROM ANYONE. THEY ARE JUNK) make sure all your piping to the turbo is good, make sure the actuator doesn't leak any where in its travel, check the wiring and plug to the control module VERY thoroughly (quickserve has ohm specs and procedures) check and monitor you TPS voltages while this happens (if it drops during this then the problem is in that circuit), watch and monitor your IMAP, Exhaust pressure, barometric, and intake temp sensors. Im sure there is more...