Truecountry Posted July 27, 2022 Share Posted July 27, 2022 186000 miles on a gu813 mp8 and i have had mack come out to help me with this troubled dog ...we cleaned 7th injector and replaced air valve at def pump regen went ok took for ever to get above 840 to 900 degrees ..all codes left that were on ...next day same doggie isnt happy i call mack tech and he said open up dpf filter and with a piece of mig welding wire see how far you can stick it in and what you see ....well it went 11 1/2 inch in any hole i placed it in random but i noticed a reddish tint in exhaust side of filter this is the big filter bottom half ....so i turned it that side down and used compressed air to blow to a white rag and its all dark red power ....i called him back he said injector cups ...now not to say he is wrong but its s good running truck no problems till now but couldnt egr cooler do this also and how can i test this before i go any farther ? also top half of filter was stopped up wire wouldnt go 1 inch in so i sent that to be cleaned with lower half ...yes we use red antifreeze so it coolant getting in filter maybe Quote Link to comment https://www.bigmacktrucks.com/topic/70179-2012-gu813-mp8-regen-problems-and-filter/ Share on other sites More sharing options...
Onyx610 Posted July 27, 2022 Share Posted July 27, 2022 (edited) Egr valve could be sticking open causing more soot, as it’s a boost leak and it causes a loss of heat which would affect regen. You will need PTT to really look and see what’s going on and do tests. I believe a way to check without is take a hose off the egr piping on the driver side before it goes into the intake manifold. If you feel exhaust coming through when it shouldn’t be like on a cold engine/at idle, it’s open….they do get jammed up so it’s a good possibility and they are operated by the computer to a solenoid with oil pressure. If it’s the cooler you can just take the inlet pipe off the cooler and look for wetness/sludge. Edited July 27, 2022 by Onyx610 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70179-2012-gu813-mp8-regen-problems-and-filter/#findComment-504462 Share on other sites More sharing options...
Onyx610 Posted July 27, 2022 Share Posted July 27, 2022 You could also do a combustion gas test on the cooling system too if you wanted. Quote Link to comment https://www.bigmacktrucks.com/topic/70179-2012-gu813-mp8-regen-problems-and-filter/#findComment-504465 Share on other sites More sharing options...
Mackpro Posted July 27, 2022 Share Posted July 27, 2022 If your regen temps are getting super high like 950-1000 degrees and kicking the regen out then I would definitely be looking at injector cups being the problem. Just last Friday I had a 2015 MP8 that would not complete a regen and had high spot codes. During the regen I could see fuel pressure start to drop and temps shoot up . Number 5 and 6 cups blown , the injector sealing surfaces were pitted so I replaced both cups and injectors. Driver never mentioned hard starting but after failed regens the truck spun over a few seconds before starting 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70179-2012-gu813-mp8-regen-problems-and-filter/#findComment-504466 Share on other sites More sharing options...
Mackpro Posted July 27, 2022 Share Posted July 27, 2022 As Onyx610 said , probably EGR system related /low boost Quote Link to comment https://www.bigmacktrucks.com/topic/70179-2012-gu813-mp8-regen-problems-and-filter/#findComment-504468 Share on other sites More sharing options...
Onyx610 Posted July 27, 2022 Share Posted July 27, 2022 Do some tests tomorrow and let us know. Not too many MP guys on here but the few that are really know their stuff. MackPro name says it all. He truly is…we look forward to helping you with this. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70179-2012-gu813-mp8-regen-problems-and-filter/#findComment-504469 Share on other sites More sharing options...
fjh Posted July 27, 2022 Share Posted July 27, 2022 10 hours ago, Onyx610 said: Do some tests tomorrow and let us know. Not too many MP guys on here but the few that are really know their stuff. MackPro name says it all. He truly is…we look forward to helping you with this. Yup this is where experience and paying attention to detail comes in ! = ( Mack pro) Not just assuming and throwing parts at shit! Watch and access what's going on start with the quick ,cheap and easy stuff! Follow his lead! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70179-2012-gu813-mp8-regen-problems-and-filter/#findComment-504516 Share on other sites More sharing options...
Truecountry Posted August 27, 2022 Author Share Posted August 27, 2022 ok guys i had to leave it alone for a few weeks had other more important equipment to work on but i did get a chance to test a few things but its still not right ... i had my bosch computer updated with new software nothing like macks ...but i noticed a test for def pump so i ran it metering valve stayed high 97 percent ....def pressure zero ...i have a sister truck to this one so i went did same test on that and 130ish on pressure and metering valve was going lower as pressure built up ...so i got def pump and it did right pressures and metering ...did filter reset and system rest .. regen like it should but would not let me do scr regen but all codes were inactive driver runs truck all day stop to get fuel shuts truck off and starts it after fueling and engine light on checked code and dosing system data valid but below normal working range ....egr valve cleaned ..down stream nox changed out values were good but also had a inactive nox code fault in the nox monitoring system i got new one same thing again it regens in about 35 to 40 mins 899 to 940ish and will drive 7 hours before hiccup and engine light only Quote Link to comment https://www.bigmacktrucks.com/topic/70179-2012-gu813-mp8-regen-problems-and-filter/#findComment-507616 Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.