RP Sensor scaling, CM849

So now that I have my mutant running, it's become apparent that the rail pressure is an issue.
I've coupled the 6.7 rail and lines to an 03 cylinder head and 03-04 injectors. Fleece 750 6.7 IP.

What I found initially was that the rail pressure maintains 26.4 until a significant throttle input, at which point it drops to 11k. I haven't researched the related DTC yet, but I'm guessing this is the strategy when rp has been unexpectedly/uncontrolled- high.

I thought I had addressed the scaling, but after reviewing the file I used, the 06 auto stock file used 180mPA as the top of the sensor range, and what appears to be 160mpa as the DTC threshold.

After digging, it looks like 21k was the max operating pressure for the CM849 engine.

So, I re-scaled the sensor to 200mPA.

My question is, where else do changes need to take place in order for this hardware combination to function? I'm assuming I will have to modify the threshold for the DTC at the least. I poked through some of the tables and parameters last night, but dozed off before I found anything that jumped out at me.

After logging the rail pressure and fca command and actual, a couple of us think the fuel delivery pressure is too high and is causing the IP to build excessive pressure. I'm going to check lift pump pressure this evening.

Did I say something wrong when I asked about the tuning? Or is it a matter of no-one hanging around that wants to talk about it?


FCA command was 0%, Desired was - 3.8%, current was 14.7mA.


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You're running a 200mpa sensor from the 6.7 correct? I'd have to buzz through a file to get the table numbers for you, but essentially just bump up the DTC limits, and look for other limiting tables that may cross reference air / coolant / fuel temp

JWhite said:

You're running a 200mpa sensor from the 6.7 correct? I'd have to buzz through a file to get the table numbers for you, but essentially just bump up the DTC limits, and look for other limiting tables that may cross reference air / coolant / fuel temp

Click to expand...

Yep, 200MPa. By bump up, am I right by using 200 as sensor range and 180 for the max operating pressure(DTC)?

Just got done checking supply pressure. 9.8psi at 2100rpm.
I'm going to swap FCA and see what happens.

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Do the early injectors handle pressure very good? I'd set the DTC limits just below what the sensor will read, 195mpa maybe. What's the max rail your tune calls for? Pressure means power, I'd utilize the capabilities you have

Just do what you feel is a safe limit above your table. Is this a competition setup, or a daily driver? Play truck?

DD/play.

I haven't modified any fuel tables on a stock file. I'm trying to keep this thing close to stock for breakin/shake-down.
I started another thread. I have some sort of hardware failure causing no control of the fca. I did some troubleshooting that to me, leads back to a failed driver in the ecm.

Thank you for your replies.

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Anyone able to find the thread about the ecm rebuilders that popped up about a month ago?

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06/07 5.9 Cummins ECM - Competition Diesel.Com - Bringing The BEST Together

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SIA has been the better outfit to fix ECMs that I have found.

Mark.

JWhite said:

Do the early injectors handle pressure very good? I'd set the DTC limits just below what the sensor will read, 195mpa maybe. What's the max rail your tune calls for? Pressure means power, I'd utilize the capabilities you have

Just do what you feel is a safe limit above your table. Is this a competition setup, or a daily driver? Play truck?

Click to expand...

I have been running mine at 28,500 for a couple seasons with a rail plug and havent had any issues yet. It made a pretty good difference in power, i dropped about 2 tenths going from 26,000, to 28,500.

I killed the **** out of this ecm last night. No rebuilding it now.

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Gonna bring this back up.
I rescaled the sensors to match the 08 sensors I used.

The 08 file scales boost and baro from ~40kPa to 354.7kPa

When I put that scale in my CM849 baro drops to 0 and boost climbs to 13, so that scale isn't going to work.

I wanted to see if someone could throw me a bone on what values to use.
I was thinking about probing the sensor and using the voltage data to scale from.

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I think I might have found my problem, I wasn't correcting the barometric pressure voltage axis to make 40.6kPa the floor.

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Anyone had an ecm flash cause dead-pedal?

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biggy238 said:

Anyone had an ecm flash cause dead-pedal?

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Click to expand...

On a gas truck. Would start and idle, that was it. I guess the file got corrupted somehow, copied my changes back over to the original base file and full flashed it.

I found out just a minute ago that it's a wiring issue that mysteriously popped up. I disconnected a harness to isolate the throttle and it's reading and throttling appropriately now.
I'll post back when I find the root cause.

For the record, I started working backwards undoing the changes I made to the file, and dropped back to the original file, and then to a stock manual file from another vehicle.



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