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Thanks for posting your fix Bro!

I was that guy 45 years ago! That said your comment above applied to me up till the point The Big V got involved ! So the always will, don't count for me! My get up and go got up and went after that! We had a good product up to that point in time ! But now its just a main stream POS Like everything else ! Ya they had there issues but they addressed them for the most part! Thankfully I have retired as of Jan 31 2022 ! Hanging it up after almost 50 years !Started with Mack in 1972 back when they were still building real trucks and were a bit forward thinking kept things relatively simple and straight forward ! Everyone said back then! Wouldn't by a Mack because you were stuck buying your parts thru them which was partly true back then BUT WAY WORSE these days! For All the Company's building the throw away trucks and equipment of this era !The generation of waste! This is how we are saving the environment! Oh well ! Sorry just rambling Cause I have the time! 😁

Also want to add here! be sure the muffler you buy is Made for a single exhaust truck 4inch or 5 inch ! There is a difference in dual and single ! We got burned once by making a dual into a single and not changing mufflers ! School of hard knocks came into play here! Just sayin

these all depend on how def you are! 😁

Bro we are truck guys here However most of this junk operates in a similar fashion Can you locate the def dosing valve it will likly be mounted in front of the after treat box? if you can remove it and check for crystal formation this would identify an issue with that injectors spray Or an exhaust leak near it also There is a possibility the def pump has failed! Again there maybe some one on the site here that is familiar with the cat way of doing things so keep checking back here!

Yup why does it start out in 4th? cause they programed it like that! It can be programed to start in 2nd but they don't! Once the truck is rolling empty or loaded the trans ecu can take a full gear or half gear what ever is needed! Slipping the clutch is not necessary but they do it! This has pissed me off since they started pushing this trany down our throats ! Why not make the trans do its job! Thats why its there!

Is it even plugged in ? Its possible they took the air cleaner off to access an reseal the EUP and didnt plug it back in done that a few times my self! Any one ever have this issue and anyone know the part number? I cant find it in Fleet Impact buts it is mounted in the intake tube and they didn't want to give me the part number for some reason. That there is no surprize the impact program is A POS ! Need to be a rocket scientist at times to operate it!

Usually this is a wiring issue as Jojo has mentioned in Our area there is Brine/ salt on the roads this time of year and it gets in to EVERTHING ,But rule out the techy end with the tech tool make sure the any codes are un related your up dates are up to date For WHAT EVER reason this makes a difference sometimes as these people keep changing stuff! Then start tareing into harness issues ! just sayin!

Totaly agree jojo ! However the way these are programed to fail the clutch early ! If your not watching these will start out in 4th gear every time ! Slipping the clutch for the first 20 feet before totally engaging! If ALL the trucks were programed to start out in 2nd there would be half the clutch wear! getting them past that magical 750 mark MAYBE how ever clutch wear is not a warrantable item so its beneficial to mack/ volvo to to program this way so why change it! A 8-10 thousand dollar clutch job is beneficial to them ! At 250000 - 300000!😡

Jojo ! This is very doable on a REAR if you got the equipment ! We have a parts washer ! This cuts the time immensely! Blo the diff to bits peal off the bearings Wash em inspect the case halfs and gears determine the parts u need ! And This is the key , GOOD PARTS people pull and deliver your parts to your bench start reassembly 6 hours to build it end to end sitting on a pallet! If you know your doing a gear set to start the parts guys can pull your bearings and gear bits for you to get you started on reassembly by the time your done stetting the top end, you can build the diff portion in an hour! If they got there shit together ! It Takes cooperation and team work but it can be done!

Your better off doing what you do ! Trying to justify someone else's actions when something goes sideways is hard to do if they make a mistake on your behalf ! And unfortunately mistakes happen as you know! No body is perfect what we do is not exact science !When you think about it, We are like vets of machinery! all different Types of animal's in our business !

The old adige ! It's hard to get good help these days! was never so prevalent as it is today! People that care are few and far between!

Bro this happend's lots at our place too! Difference thou is we don't got a tool budget if its something we run across we need we will build it if the tool looks to overly priced by the volvo /mack criminals! There are also things you can do on MP engines to find leaks that are NOT In the manual ! On an MP8 if you you got a squeal/ leak simply force a regen on it ,this will usually build enough pressure on the exhaust and intake side once its making the noise, run warm water over the manifold/turbo and egr cooler plumbing joints this usually will uncover what your looking for as a sound change when the water hits the effected area! Just shit you learn over the years you know how it goes!And usually its the school of hard Knocks that you learn from ! The above MP8 story there was learned late on a Saturday afternoon at going home time after a EGR Cooler change! 😡

yup any thing up to 40 psi depending on what your looking for!

You done Good!

jojo we built a setup for boost checking these engine two flat plates capping the exhaust and the inlet ! We also had to plug this valve off after testing it to see where it was blowing off at.remove it and put a pipe plug in its place then pressure up the exhaust and intake system to check it all for leaks this test was ultimate for leak checking Absolute coverage as far as leaks went!You can even check the turbo drain tube for blow by which was a fairly common issue on these and some AI turbos!

Not saying this is the problem however these engines are or should be equip with an over boost valve and tube ! That valve may be sticking open! Its the 1 inch tube on the back of the intake horn on the engine the tube attaches to the exhaust pipe! this valve is apparently set to lift off at 25 psi if it is sticking this could cause an intermittent boost scenario. see stax comment

Just to add a little to Joes advice all good suggestions! However! If the engine is not suffering from performance issues or throwing up engine codes other than an intermittent annoyance miss .I personally would not chase this! Only because I have done this before with no success . However if you do pursue it and you find success Please post it here! I believe it has something to do with programing ,the engine ecu is trying to make up for a cylinder imbalance in my opinion! Now that being said ! you could up root all the eups or the one you suspect and check the springs to be sure they are not broken do the swap if you want! but remember that the cal codes need to follow the eups as you swap them!

Yup Good call bro !Joey IS THE MAN!

10 psi

So before jumping to far ahead here the 7th injector is likley coolant cooled on that truck check that before condemning the thing! also the egr is controlled by the dpf on the egr tube if its polluted with coolant It will command the valve open if the cooler is restricted! Being deleted we don't know what they have done to this programing! Remove the egr hose front of the EGR cooler first cause its easy If it is soaked you have your answer ! Then check the injector, if the cooler is OK!

SWEET Looking unit! RDSX?

This here is the most odd post for me ! We have in our yard a fire truck converted into a food truck ! It is almost identical in spec! The engine in the unit we have had a leaky liner and took out the bearings by being run with water in the base a real shame The guy bought it for 15000 4 years ago if that gives you an idea for its worth! Unfortunately He put 15000 in grilles and cooking equipment into it then the motor createred !

I got to think you need to do the air in fuel test after the engine is warm I would lean to cups as you are thinking there( How ever) there can be other issues as mentioned sticking VGT when warm , EGR Valve commanded open due to low EGR Flow readings . This engine being deleted we have no idea what the program is doing in that area? Try unplugging the EGR valve and see if this changes your situation!

yup i must agree 38 psi is way to aggressive to much fuel ! Its Either tuned up or something is a miss in the governor! I have seen the fuel stops fall off on the ambac pumps which would cause this little engine to perform like a race car! A turned up e6 will self destruct in short order by breaking main bolts or cracking the block at Number 4-5 main if left like this! I Guess pulling the pump is highly recommended with that view on it!