Low boost, higher egt's

[Rawze]

(04-05-2016 )simon999 Wrote:  I was at cummins dealer today and they show me new turbo without actuator. I moved vg ring gear it moves same travel like mine turbo. So I guess that my turbo is good. But is diifferent design than in 'turbo inspection video'

I have done dozens of CM871 turbo's and it ALWAYS goes to the half a hole position on all of them. I have seen a few that did not do this form new, and they were bad from new.


On the newer CM2250 and 2350 engines, and their turbo's, I cannot tell you for sure yet. I have not had one apart yet, but i do know that The new turbo will also usually come with a plastic piece that will show you travel range.

[simon999]

I installed another actuator , tested turbo travel range with plastic gauge was together with actuator. Im still getting same 20psi boost max and high egt`s. Today I monitored insite and 'exhaust gas pressure' shows 30inHg (0.88v)while engine is Off. Is it suppose to be like this??? What pressure suppose to be while idling or driving?
Now when engine is at idle it shows about 32-33inhg at 650rpm , 35inhg at 1000rpm, 39inhg at 1400rpm. I tried with another older exhaust backpressure sensor but its same thing.Also when driving if push pedal and boost goes more than 10psi insite shows 'engine torque mode' changes from 'accelerator' to 'torque limit' mode.

[Rawze]

(04-14-2016 )simon999 Wrote:  I installed another actuator , tested turbo travel range with plastic gauge was together with actuator. Im still getting same 20psi boost max and high egt`s. Today I monitored insite and 'exhaust gas pressure' shows 30inHg (0.88v)while engine is Off. Is it suppose to be like this??? What pressure suppose to be while idling or driving?
Now when engine is at idle it shows about 32-33inhg at 650rpm , 35inhg at 1000rpm, 39inhg at 1400rpm. I tried with another older exhaust backpressure sensor but its same thing.Also when driving if push pedal and boost goes more than 10psi insite shows 'engine torque mode' changes from 'accelerator' to 'torque limit' mode.

disconnect the exhaust pipe just before the DOc (first can) and take it for a test spin to see if you get more boost. If so, then it is likely a clogged can or exhaust pipe somewhere.

[simon999]

I disconnected small pipe(was clean) from exhaust manifold going to exhaust pressure sensor housing and then checked with insite(engine off) It was showing same 30inhg 0.88V. Then I took sensor out of housing and left connector on it , checked insite (engine off) it was same 30inhg (which is ~15psi)!!! Then I took connector off and checked insite, now shows 0ingh-0v. I am thinking this is bad sensor? or bad harness?

[simon999]

(04-14-2016 )Rawze Wrote:  

(04-14-2016 )simon999 Wrote:  I installed another actuator , tested turbo travel range with plastic gauge was together with actuator. Im still getting same 20psi boost max and high egt`s. Today I monitored insite and 'exhaust gas pressure' shows 30inHg (0.88v)while engine is Off. Is it suppose to be like this??? What pressure suppose to be while idling or driving?
Now when engine is at idle it shows about 32-33inhg at 650rpm , 35inhg at 1000rpm, 39inhg at 1400rpm. I tried with another older exhaust backpressure sensor but its same thing.Also when driving if push pedal and boost goes more than 10psi insite shows 'engine torque mode' changes from 'accelerator' to 'torque limit' mode.

disconnect the exhaust pipe just before the DOc (first can) and take it for a test spin to see if you get more boost. If so, then it is likely a clogged can or exhaust pipe somewhere.

Thanks will try

[Rawze]

The exhaust pressure sensor reads the atmosphere pressure. it should read close to 15 psi, or the psi at whatever elevation you are at.

[ntadiesel]

The manifold back pressure sensor reads from absolute zero so if you're close to sea level you have to take away 14.7psi from whatever insite reads

[gearhead]

You said that it has @m*m^2 on a 2350? have you tryed comparing the manifold pressure of the ecm to your gauge (if you have anouther gauge) to see if sensor is reading right. Also i have seen turbo speed sensors go bad and cause this. Unplug the turbo speed sensor and take multimeter and ohm it see if it has resistance.Even if ecm shows turbo speed it could be showing calculated value. Also is your turbo compressor inlet temp sensor reading corectly? Five main things if @m*m^2 is done turbo speed sensor, exhaust backpressure, manifold pressure sensor, Turbo or actuator and turbo inlet temp sensor reading wrong.If no @m*m^2 I would need a list a hole page long and still probably not explain it all.

[simon999]

So I climbed under truck and gently hit multiple times with hammer to def decomposition tube. I started to drive my boost climbed. When we did #m%m^2 we forgot def pipe that has screen in it. That screen probably clogged.