04-30-2023, 07:19 PM
Steve,
Sometimes a small crack can cause an intake of air rather than a noisy leak. It depends on the flow and scavenging effect. The area between the DPF and SCR is insulated by design because of the need to keep the exhaust gasses hot. Too bad there is no sensor here to monitor the temp. Maybe a probe could be placed against the pipe, with the insulation on top. My gut still tells me the problem is here somewhere.
I would be suprised if the ECM by itself is causing heavy overdosing. Maybe something is telling the ECM that the emissions are off somehow. Maybe something to check would be the EGR. Maybe a restriction or cracked EGR itself. I don't think you had a check engine light but there may be codes that show sensor feedback that would tell the ECM to add more DEF.
In any event, the pipe between the DPF and SCR needs to be clear of DEF crystals or there will be a tendancy for additional crystals to form.
You are a super capable guy and you'll soon fix the problem you've been "blessed" with.
Sometimes a small crack can cause an intake of air rather than a noisy leak. It depends on the flow and scavenging effect. The area between the DPF and SCR is insulated by design because of the need to keep the exhaust gasses hot. Too bad there is no sensor here to monitor the temp. Maybe a probe could be placed against the pipe, with the insulation on top. My gut still tells me the problem is here somewhere.
I would be suprised if the ECM by itself is causing heavy overdosing. Maybe something is telling the ECM that the emissions are off somehow. Maybe something to check would be the EGR. Maybe a restriction or cracked EGR itself. I don't think you had a check engine light but there may be codes that show sensor feedback that would tell the ECM to add more DEF.
In any event, the pipe between the DPF and SCR needs to be clear of DEF crystals or there will be a tendancy for additional crystals to form.
You are a super capable guy and you'll soon fix the problem you've been "blessed" with.
Bob & Dottie
Newell 1261 & Jeep Grand Cherokee fulltimers
Past Teton Reliance 45' 5th wheel
Custom Volvo VNL780 tow vehicle
2014 Smart car