Replaced actuators.....now this...Need imput.

[preacherboy24]

After putting in reman injectors truck was running better but still seemed to have an intermittent miss. I decided to swap in some actuators I pulled apart, cleaned and checked a while back. Truck runs better but all of a sudden my boost is crazy. I can coast down a hill and be running 8lbs of boost. It never goes over 35lbs but when I kick on the Jake it goes to almost 20 and settles to 15. I know how this engine acts when you first crank it up after pulling actuators and I am thinking something happened to my turbo. Again....I can coast (no fuel to the engine) and be running 8lbs of boost. I have a mechanical gauge and it matches what my computer is saying. I have a cm870 and will prolly just go with an HX60 and reprogram the VG out of it since the actuator setup on an 870 is junk in my opinion.

[preacherboy24]

By the way my pyro (hose clamped sensor to manifold) isnt reading any different than before.

This is what I am boosting coasting down a hill with no fuel to the engine......

[Wiseman]

Before you jump to HX60 , I urge you to inspect your turbo . How it travels . Then visual on cage and ring . Although the actuator have a very strong spring , something is preventing the cage from returning back all the way . Then check the air controller below compressor . It will not cost you anything. But at least you gonna know where's the problem.
I think 15 at full engine brake is on the low side . Almost like cm570 . That leads me to think the cage doesn't travel what the controller said.

[Rawze]

I think there is a few procedures on quickserv for checking the proper travel of the turbo. I have never worked on CM870 but I am pretty sure there is a calibration procedure too.

I saw a Cm871 truck do something very similar one time. turns out it had jumped into high altitude mode permanently because of a bad sensor.

Also, it is never a bad idea when you replace a bunch of new parts that effect how the engine runs to get it tweaked/dialed in again and have the latest ECM updates done to your type of tune. Not be a bad idea to have perhaps gearhead or someone get a close look at it and give it an update it to the latest changes avail etc. -- just some thoughts any ways.

[Rig Wrench]

No vgt calibration for the 870. Just bolt on and go. I don't blame you for goin to hx60 if your turbo is bad. Good or bad programming, stock or otherwise, the air vgt don't seem to live as long a life as the electronic do. A long lasting one tends to be more the exception than the rule.
Insite does have a turbo travel test you can perform. You may need disassembly to find the issue though. This sounds like a possible imap sensor on the fritz though. had one play games on me a while back. Showed 5lbs of boost not even running, just with key on.
I believe properly tuned the hx60 will return as good if not better mileage than the air vgt, and if your looking to make big power, probly better off. I will be doing this swap on a 565 in a Pete before too long. I'll be sure to post results

[Unilevers]

if your gonna do it - hx60 is the way to go.

[Brock]

I don't see a issue........... any truck I've ever driven made boost while jaking.

[Wiseman]

(07-13-2016 )Unilevers Wrote:  if your gonna do it - hx60 is the way to go.

I rarely use pedal brakes. Mostly to keep truck standing still at traffic lights and such. All the rest is engine brake .
What's your opinion on HE551V vs. HX-60 on providing more boost during engine brake use in the range of up to 1650rpm ?
Its not like I'm gonna kill the engine if I let it revv up to 1800 rpm during engine braking, but it seems there's where the HX-60 will get up to par with HE551V when at 1550-1650rpm .
Seem like trade off ...
Ahhh.... And I forgot to mention something! ALTITUDE-density of air up in the mountains.
VGT should correct its position to compensate, and the fixed vane ...???

And again!!!! I'm talking strictly about engine braking! Not drivability compatibility between both!

Clarification:
The "brains" of CM870 and CM871 work on significantly different way from each other. So let's not mix cm871 here .

[Unilevers]

you will lose some jake power - there is no way around it.

with a proper manifold and a hx60 the 870 and 871 will peak up to about 28 psi during jaking - well this is not as high as a vgt will get it is close and is sufficient for most. that stupid Chinese holeset detroit turbo the other guys use will get like 8 psi max under jaking and will have next to no jakes.

im not saying everyone should do it but the hx60 is a nice turbo if you must go fixed vane - obviously the only way to do it is with the wastegate unplugged aswell.