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Rawze · 01-24-2026, **(Subject: Cm870 low boost high egt )**

(01-23-2026 )Oilysnowman Wrote: ...
Quote:Those sensors do not need to be bypassed as part of a de-mandate.

RR looked into this issue for me, when he turned on those sensors we got egr codes.

turbo inlet and ambient sensors operating correctly should not be causing egr related faults if things were turned off properly related to the de-mandate.

Oilysnowman · 01-27-2026, **(Subject: Cm870 low boost high egt )**

(01-24-2026 )Rawze Wrote:
(01-23-2026 )Oilysnowman Wrote: ...
Quote:Those sensors do not need to be bypassed as part of a de-mandate.

RR looked into this issue for me, when he turned on those sensors we got egr codes.

turbo inlet and ambient sensors operating correctly should not be causing egr related faults if things were turned off properly related to the de-mandate.

I’ll talk to RR about that yet then. I connected to one of the other trucks that has RR tuning, and the sensors showed the same as mine. I hadn’t talked to him about his truck since the day he got his truck reprogrammed, and then it sounded like it was working perfectly, but he said his wanted to run warm, he had to put a shim in his actuator to keep it cool. I checked his codes while I was in there and there were quite a bit, so quite possible nothing to do with programming. I saw cylinder imbalance and fuel filter pressure imbalance so probably something else going on.
I had an injector go out, changed it truck works a little better, but still low boost, high egts, so I put a shim in my actuator as well, didn’t seem to make much of a difference. Seems almost like it’s tied to altitude, I was doing trips up north, it seemed the farther north I went, the worse it got. It was always colder there, so I assumed temperature, but yesterday it was warmer there then at home, but the truck still worked the same there and coming back it got colder but it was working better. I watched my altitude both ways, and the further north I went, the lower the altitude got. I was watching Insite and up north it kept getting air density derates. Didn’t watch for the derates further south, but the altitude was a lot higher and it was working very nice. Between my minimum and maximum altitude it seemed to be working fine as long as it was between 1450 rpm’s and 1550 rpm’s. Any lower or higher, boost went down, egts came up. Today another injector went out, found out about it when I shut the truck off, and it kept running on what sounded like one cylinder, it sounds fine at idle. Insite showed cylinder two failed cylinder performance test periodically only at very low rpm’s. Bubble test confirmed it, got big bubbles. I’ll be changing it tomorrow. Cylinder two and cylinder six both had injectors that were under a year old, but they both failed now. Is something causing them to go? I swapped timing and metering actuators and the problem stayed at cylinder two now, occasionally all three of the front ones showed fail, but mostly cylinder two, I assume it’s making the other two on the front bank fail occasionally?I also saw differential pressure without egr derate come on when activating my engine brake.almost new barometric pressure sensor that came with my engine wiring harness, and the reading on Insite matches my phone, and my other pressure sensors on a cold engine. Is there any programming that would affect air density?

Rawze

what are you calling high EGT's?.

Oilysnowman

(Yesterday )Rawze Wrote: what are you calling high EGT's?.

1000 Fahrenheit post turbo. Occasionally it shoots up fast to 1100 when I shift and that’s when it gets the pressure differential derate actually, then the the boost shoots up to 40 or just over and cools it down then the boost slowly drops back to 33 ish. It was some other derate just for egr that came on with the engine brake. Sorry got my wires crossed there.

Rawze

(Yesterday )Oilysnowman Wrote:
(Yesterday )Rawze Wrote: what are you calling high EGT's?.

1000 Fahrenheit post turbo. Occasionally it shoots up fast to 1100 when I shift and that’s when it gets the pressure differential derate actually, then the the boost shoots up to 40 or just over and cools it down then the boost slowly drops back to 33 ish. It was some other derate just for egr that came on with the engine brake. Sorry got my wires crossed there.

That EGT is not excessive, but the boost going above 37~ish is.

1050 - 1100 F (post turbo) is the upper end of acceptability for the ISX under max operating loads.

what you describe almost sounds more like the arm is hanging up?.. is wonky?. etc. - that could be the turbo itself.
related info: https://rawze.com/forums/showthread.php?...8#pid54418