steeler Posted March 11 Share Posted March 11 Hey all, I normally don't run into something like this that isn't fairly easy to diagnose... But I'm working on a 2018 mp8 that needs parked regen daily. Originally came in shop with whacky exhaust temps during regen. Dpf filter was junk. Replaced filter and new 1 box. Exhaust temps during regen look great, soot drops to 0, but rises quickly during the day. I replaced the Dpf diff pressure sensor and all temp sensors during this process. Engine runs great. Vgt sweep is good, egr cooler not leaking. No exhaust or boost leaks. A little stumped! Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/ Share on other sites More sharing options...
fjh Posted March 11 Share Posted March 11 Egr diff sensor ? Venturi ports clogged? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571152 Share on other sites More sharing options...
steeler Posted March 11 Author Share Posted March 11 3 hours ago, fjh said: Egr diff sensor ? Venturi ports clogged? I did check ports and they are clear. Customer wants to go ahead and throw a set of injectors at it. I'm skeptical... I've seen bag injectors cause funky regents, but I haven't seen them cause frequent regen. Not on a mack anyway. I did run into that with a Cummins. Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571160 Share on other sites More sharing options...
fjh Posted March 11 Share Posted March 11 44 minutes ago, steeler said: I did check ports and they are clear. Customer wants to go ahead and throw a set of injectors at it. I'm skeptical... I've seen bag injectors cause funky regents, but I haven't seen them cause frequent regen. Not on a mack anyway. I did run into that with a Cummins. Fuel pressure at 7th? Just throwing it out there! Not a guru by any stretch! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571164 Share on other sites More sharing options...
steeler Posted March 12 Author Share Posted March 12 11 hours ago, fjh said: Fuel pressure at 7th? Just throwing it out there! Not a guru by any stretch! And I appreciate you! After treatment fuel pressure is 65. All the numbers during regen look great, but something is causing it to soot up pretty quick while driving. Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571188 Share on other sites More sharing options...
fjh Posted March 12 Share Posted March 12 Thanks ! I try ! Did you physically check the turbo rack by feel! Could be sticky ! learn data reset? Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571204 Share on other sites More sharing options...
fjh Posted March 14 Share Posted March 14 Steeler if you find the fix post it! Hopefully the parts canon shooting injectors at it is the fix! it can be so many things with these dam emissions engines! 🙄 Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571330 Share on other sites More sharing options...
The Heinz Posted March 14 Share Posted March 14 (edited) Is the 7th injector/AHI nozzle sooted up or the right one? A 2018 should have the high-flow nozzle, modern part number 23937771. If that checks out, there wouldn't be much else causing it other than injectors or a hung open EGR valve. Edited March 14 by The Heinz 2 Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571353 Share on other sites More sharing options...
fjh Posted March 15 Share Posted March 15 18 hours ago, The Heinz said: Is the 7th injector/AHI nozzle sooted up or the right one? A 2018 should have the high-flow nozzle, modern part number 23937771. If that checks out, there wouldn't be much else causing it other than injectors or a hung open EGR valve. You would with think An open EGR there would be power issues! Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571404 Share on other sites More sharing options...
steeler Posted March 18 Author Share Posted March 18 Well, injectors were a parts Canon whiff! Took it for a 40 mile test drive and went from 0% soot to 73%. Checked to make sure aftertreatment fuel was actually shutting off to 7th injector, which it is. No egr codes but ran egr test and appears to be closing 100% Pulled turbo outlet, didnt appear to have excessive smoke, 1 little puff of black when you first mashed the throttle, then clear. I drove it with turbo outlet off and did not see any smoke trailing behind. I'm beginning to wonder about the Dpf filter. We put a recored one in it from a company that cleans/recores here locally. So it's not an oem new filter. BUT, I'd be looking at the parts cannon again for 3 grand to try an oem filter. Just not sure what to toss next. Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571626 Share on other sites More sharing options...
The Heinz Posted March 18 Share Posted March 18 Did you replace the PM sensor already? I'm not sure if that's your problem, or how to actually diagnose it. I know that they usually throw a code when they fail. Part number for that should be 24307015 if you want to research it. Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571627 Share on other sites More sharing options...
steeler Posted March 18 Author Share Posted March 18 17 minutes ago, The Heinz said: Did you replace the PM sensor already? I'm not sure if that's your problem, or how to actually diagnose it. I know that they usually throw a code when they fail. Part number for that should be 24307015 if you want to research it. I did not replace the pm sensor. The problem is more of the Dpf differential pressure rising to fast from either clogging at a very fast rate, or a filter problem. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571628 Share on other sites More sharing options...
fjh Posted March 19 Share Posted March 19 Good luck bro ! I'm tapped ! All the cheap and easy amo has been used the rest is expensive and you already started down that road! keep us posted! I ask this thou ! Does the DPf Look face Plugged did you actually run some wire down the comb ?? Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571654 Share on other sites More sharing options...
steeler Posted March 20 Author Share Posted March 20 On 3/19/2025 at 10:37 AM, fjh said: Good luck bro ! I'm tapped ! All the cheap and easy amo has been used the rest is expensive and you already started down that road! keep us posted! I ask this thou ! Does the DPf Look face Plugged did you actually run some wire down the comb ?? It does not look plugged as I would normally see with an engine issue. I can shine I light right thru the doc and the Dpf isn't black on the face. After I replaced the Dpf, truck came back 3 days later with the frequent regen so we sent the Dpf out to have it checked and they said it was clogged, although I couldn't see anything visually. I'm throwing an oem Dpf on it now, just to see if the truck doesn't like aftermarket. I've run into that with Cummins a few times where the truck wouldn't like aftermarket, but worked perfect with oem. Never seen it with Mack/Volvo though. Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571689 Share on other sites More sharing options...
fjh Posted March 20 Share Posted March 20 Well hope it does the trick ! next amo is a turbo! If it’s not full stroking it could cause the issue! Either way Volvo wins! 20 grand down the crapper! Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571696 Share on other sites More sharing options...
steeler Posted March 20 Author Share Posted March 20 Ok, went with oem filter, test drove same route as before. Probably 50 miles. Soot level with oem filter went from 5 to 31 after drive. With aftermarket filter I went from 0 soot to 77...... Big difference Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571705 Share on other sites More sharing options...
fjh Posted March 20 Share Posted March 20 Still sooting up quick don’t you think!? That said bob tail ain’t working it! See what a day or twos work does for it! Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571721 Share on other sites More sharing options...
steeler Posted March 20 Author Share Posted March 20 Yeah, going to release it to the customer and let them run it and see what we've got. I'll post the result in a few days! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571728 Share on other sites More sharing options...
Joey Mack Posted March 20 Share Posted March 20 I feel your pain...good luck. Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571730 Share on other sites More sharing options...
fjh Posted March 21 Share Posted March 21 Yup hopefully the canon was aimed at the right spot this time! Sooooo hard to find this shit some times! Once you’re down to canon fire it’s not easy you got to draw the right straw! Fingers crossed bro! I’m with Joey! Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571737 Share on other sites More sharing options...
The Heinz Posted March 21 Share Posted March 21 I haven't heard of a system causing that much trouble, that's rough. Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-571770 Share on other sites More sharing options...
Popular Post steeler Posted Wednesday at 03:19 AM Author Popular Post Share Posted Wednesday at 03:19 AM On 3/21/2025 at 5:08 PM, The Heinz said: I haven't heard of a system causing that much trouble, that's rough. Lol if it can happen, it'll happen to me! Had an mp today that would only run for 10 seconds then shut off, losing communication from engine ecu. Turned out it was a leaking freeze plug in the turbo, behind the vgt actuator. Coolant had leaked in between turbo and actuator, getting inside actuator and shorting out, causing the ecu to go dead. That was a first for me. As far as my original post, I don't want to jinx myself but 2 days in and so far the truck is doing fine. Fingers crossed that it just didn't like the aftermarket Dpf! 3 Quote Link to comment https://www.bigmacktrucks.com/topic/75271-frequent-regen-issue/#findComment-572055 Share on other sites More sharing options...
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