Cm 871 boost pressure

[Valley11]

I have a 2010 cm871 seems no matter how easy I try to speed up it wants to boost up to 30psi up to 37ish. Even to hold highway speed boost stays around 30psi. It was demandated first by someone not on this sight then fixed up demandate by someone on this sight. The truck seems to run good seems to be high boost according to other posts people say they can keep boost under 20psi.

[Waterloo]

Sounds like you have issues... Leaks, bad CAC, or... When was the last time you hosed out the CAC? How many miles on the motor? Have you gone around the CAC and checked for any leaks? Replaced the boots, and clamps?

The Turbo Actuator, do you have an Inline reader and Insite software? You will need that if you are going to keep this truck.

If you are over or around 800,000 miles, it is more than likely time to replace the CAC... But, my best guess, is the programming, and any damage done with the bad tune... I'm thinking the turbo actuator. But, we need an Inline reader and the software to properly diagnose. My gut "feeling", but others will chime in and hopefully sort this mess out.

[Signature620]

I restricted or leaking CAC would cause low boost, not high boost.

I would start by checking what operating mode the engine is in and check that sensors like intake manifold pressure, barometric pressure, accelerator, etc are reading correctly.

Was it over boosting the whole time or has this only recently started happening?

[Valley11]

It has under 500,000 km on it still. Farm truck pulls super b grain trailers I don’t drive it that often usually someone else but I did this past week and noticed boost seems like might be little high very responsive as soon as give little pedal right to 30 psi boost. Yes I have insite I did not have it hooked up while driving to watch anything tho

[Chamberpains]

Your demandate may also need to adjusted if its that touchy. Ive been working with Mommaburt on mine for months of testing and trying. The current one I have in now is exactly what you describe and I'll be contacting him to adjust a little of this touchyness out. It may be worth contacting whoever did your tune and let them know your concerns. If they are truly one of the recommended people on here, then they can easily and safely tweak things.

[Rawze]

Trucks with big square front ends can be a bit touchy to set correctly with regards to the turbo. Unlike an aero truck with a more predictable flow rates on the intake, there is little to no restrictions in those 4"+ piped front ends and hi-flow exhaust systems. This makes them a bit more touchy, especially if whoever did the adjusting on it is unable to test drive it themselves to get it dialed in. To put this into perspective, from what I have seen, It becomes about 1 in 30 trucks or so (large front end trucks only) that usually need additional tweaking on the turbo to dial it in just right for a particular application. This is solely due to how touchy they are with their larger CAC, intake, and exhaust compared to the typical aero truck.

The trouble comes by way of the person doing the adjusting on it. If they can't test drive it themselves because they are "remotely" making a program for it, then they are not able to see exactly what is going on when it goes down the roads. You have to tell them accurately what it is doing and make them aware of these things so that adjustments can be made.

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Over-boosting can be downright harmful to an engine if set too high ...

If you get on it as hard as you can, what will the boost crest at?. How high can you make the boost go if you really try hard and at what RPM ranges?. Can you get it above 39 psi?

You also need to consider that you drive a truck with a big square front end. Most these ppl on the forum here drive aero trucks and below 80,000 lbs. What you see may in fact be normal for your operations if your heavy like that all the time + it fighting the wind.

PM whoever did the programming on it ... maybe give then a ring ... tell them what the details are .... and I am sure they will be more than happy to adjust on it. There is not a single person on this forum who is able to adjust on it, that would not go out of their way to ensure things are as correct as they can be... but they have to also know what's going on in detail, or they will never know what needs to be corrected.

[Chamberpains]

Just as maybe some help for the guys that do remote tune, I've had Mommaburt live monitor a test drive through Insite and TeamViewer. I use the USB or wifi connection on my phone and tether the internet to my laptop. I also have a 2nd phone to keep direct voice communication with him so he can ask questions or requests of things for me to do while on the test drive.

Tether your phone to the laptop and borrow someone else's phone if need be. This give the remote tuner a live look at whats happening.

[Valley11]

Thank you wondering if this is normal boost pressure. Boost pressure will stop at 38-39. I will try to get in contact with Uni and see if some adjustment is needed