Loss of boost

[Rawze]

(08-18-2016 )Pr0fit Wrote:  2007 ISX when I accelerate turbo kicks out cooling fan kicks in , could it be turbo actuator controller ? It intermittent problem ! Thanks in advance for your comments !

I have heard of this before on CM870 trucks (EGR but no DPF). The symptom has no fault codes either...

I don't own one of those trucks, but I have had it described to me before by someone who had this happen to them ... Here is how I understood it ...

On some trucks with CM870 engines, BOTH the turbocharger Actuator (Air operated) AND the Engine fan are fed from the same air supply line ...

What is happening is that the air supply circuit that feeds the turbocharger and the engine fan is on the same tap from the supply. If the turbo actuator (air operated) develops a large leak, then it bleeds the air down from this line and the engine fan kicks on instead, because the air pressure in the line drops below 90 PSI. Also, on some trucks, there is a small in-line filter that feeds this circuit that can get clogged and cause the same effect. -- Either way, it is the fact that you are loosing air pressure in the circuit that causes it.

I have also heard stories of this happening where one air tank can cause it if it does not stay above 105 PSI like it should.

It could be anything that causes the circuit not to have enough air in it... Cracked line, Bad turbo actuator or controller, bad supply to the air tank that feeds it, leaky fitting, etc.etc.etc.