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Suggestion Take the venturie tube and def sensor off and clean them and while you’re at it blow out the egr cooler! Open the egr valve with ptt with enge running to blow out the crud !

check the air inlet system for rags bags and bird nests! Black smoke is a lack of air problem not fuel or Electrical! also I have seen where the little plastic rain cap on an MR can suck down maybe this is could be happening on the RD and cap off air to the engine check that or remove it see if the problem goes away! the other Possibility is the truck equipped with an air cutoff valve Oil PATCH truck or gas hauler ? The other thins to check for is the charge air hoses to the engine could be rotten and coming apart inside and are creating a flapper valve inside the hose where you can't see it! if any of the hoses look rotten change em!

Are you able to update with your PTT ? Maybe do an up date! and try again I find it odd that that recirc valve is going off I always thought it was engaged to heat the air ! humm! Onxy Macpro your up!

Yup good job! 🙏 so just as a note if you look at the pump you can see there is a multi fingered spring attached to the governor drive gear you should check that for evidence of wear ! That is an over run clutch if that shows evidence of a lot wear it needs to be addressed as if it gets to weak the engine can over speed and or run away if your not paying attention ! These were updated in later years to a flexible nylon rubberized affair coupler as they were more reliable! Also obviously a ANY wear in Any of those moving parts shafts and pins will contribute to surge in these pumps so you need to pay close attention to all wear parts ! Very well explained vid by the way!

good call Onyx ! Also do you have any exhaust leaks on the accordion tube ( common issue) or anywhere on the engine side of the of the system exhaust gaskets are another( common issue ) these things don't take kindly to exhaust leaks inspect that tube and gaskets closely ! Also check for broken bolts and cracking near the front of the intake Manifold! Just sayin!

So when the the compressor runs it puts some load on the engine! This helps hold the engine at a stable rpm! When the compressor unloads and the air drier purges operated by the governor on the compressor s the engine now has no work to do! So wear on governor parts linkages lets the rack float in the loose zone and varie rpm’s 50 or so rpm ! Just my thoughts on it! simple wear and tare!

Not guru how ever what is the fuel pressure during regen?I believe a stuck turbo can cause this issue as well!if any of the younger folk are around they may chime in on this!

Three things ! Loose yoke bolt, loose shift fork bolt! Now the hard one worn synchronizers !

No engine brake?

This here is a big red flag for me ! It ran like a top for about a day, then one of the springs broke on the aftermarket rebuilt injector. Within a few minutes of replacing the injector the knocking started.I agree parts cannon not the best! How ever if you can get it nailed down to a cyl Then swap injectors? Sounds like fuel knock to me but I'm not there !🙃

Any engine codes? Cam shaft replaced is it in time?

Might help to know which engine you have MP8 Or 7 ! Also can you duplicate the sound stationary ! MP8 These have a history of the idler gear coming loose and can cause a rattling knocking sound at the rear of the engine!

Yup it don't get better than this! Mack school on line!

If you got a sticky or lazy plunger it may help just something to try!

You may have sticky plunger in that pump it’s just something to try!

Any gap or slight moment on the beakover lever between the two pieces will cause a surge! Just saying! Also does the idle vary with the truck facing up hill or down if this is evident it could be general wear inside the pump! also there are two springs inside the governor that control speed a big and a small and if there is a small gap between them it can also surge! Those shims are behind the the round cap 4 bolts at the back of the pump! You say the pump pins ect were new was the pump rebuilt or just the governor part?

My DB is far from restored ! More like abused! Still starts and runs great 5500 of high abuse hours ! the new to me 580 will share the load now!

Yup that always baffled me! all the designs were the same for almost all but, the few got the fix! and a bandaid Boot ! Hummmmm! same old same old!

Nasty!

Sweet unit! relatively stock looking is the alt factory ? been thinking on doing an Alt on my Davey brown!

long ago in the V8 era We would save back out of warranty cam and lifters !I found out they were placing claims on engines that hadn't failed that were still under warranty so they could extend warranty to some guys that needed to get out of a jam! Noble in a way but still thievery on the dealers part! Stealing from the warranty program to have a happy customer ! Maybe kind of a win for everyone in a round about way!

I have a sugestion Maybe try runing some fuel conditioner like Howes or Standyne lubricity formula for a bit see if this changes your situation!

Possibly judging by the come back leaks ect just wam bam thank you man ! Didn’t check their work just horse shit! Done now attitude!

meanwhile the truck sits, insured, licensed, missing revenue, but the dealer gets paid. It's a F@$*ing joke. Yup bunch of turds! And escalate this higher up BS at its finest! Getter done!

There are shit loads stuff you need to clean and check after an egr cooler failure Venturi tube dp sensor boost sensor top of the dpf just to name a few was all that done first go around? Or were they just doing one thing at a time!A crack in the head still possible so is injector cups is it still bubbling? And if it’s warranty it’s their problem go higher up ! Long as you’re with in your warranty miles and time it should be on them! Just lasyness!