| Cm870 drivability woes |
| 03-23-2026, (Subject: Cm870 drivability woes ) Post: #1 | |||
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| Cm870 drivability woes Hi, newbie to the forum here just looking for a second opinion on this cm870 I’ve been trying to sort out Backstory: Cummins recon cm870 cpl8518 565hp was dropped in this truck 3000h ago, since then it had a whole pile of work done on it including a head, injectors and fuel/timing actuators and somewhere along the way the egr had fell off also I’ve got the mechanical side sorted out, it had another injector with a bad metering check valve and opposite bank timing actuator. But it still has some quirks to it that I believe are just tuning related now. At idle most of the time it will command very low turbo speed and start to haze, then for no good reason or when the idle is elevated it will kick up the turbo to ~20k and purr along nicely. During shifts there is usually a lag, almost like a dead spot when you get back on the throttle. Driver says it lacks power from what it had before the butt sniffer fell off If anyone (rawze?) would be interested in taking a peek at the cal just to confirm my suspicions that would be great. I’m by no means a tuner but I can find my way around the software well enough that I’ve done some tinkering on my own stuff that hasn’t blown up, I’m just not comfortable making the call on someone else’s engine. Also what I’m seeing is not at all the way I’ve been taught and self learned how to make the butt sniffer go away What I’m seeing in the file that really sticks out to me: -mass charge flow tables flat line to “2” in the lower quadrants -density fuel limit just spikes at 1500rpm and flat lines -post injection removed -fair bit of timing added in places | |||
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| Messages In This Thread |
Cm870 drivability woes - DrDave - 03-23-2026 RE: Cm870 drivability woes - tree98 - 03-23-2026, RE: Cm870 drivability woes - DrDave - 03-23-2026, RE: Cm870 drivability woes - Rawze - 03-23-2026, RE: Cm870 drivability woes - DrDave - 03-23-2026, RE: Cm870 drivability woes - Rawze - 03-23-2026, |
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