Onyx610

You never said it was as soon as you turned the key on, if it was when it was running and the boot was leaking it would pry be because of the cold outside air and warm engine air mixing and throwing the sensor all over the map. That’s my guess anyway. fjh has a good reason for suggesting that, he really knows his stuff. Anyway sounds like a bad sensor to me. I’ll check the book tomorrow morning for a ohm test or something.  

Anything been done to the truck before these codes came up? Looks like from some quick looking around these are mostly fuel codes? One I see is for the fuel pressure relief valve, I would start there as that could be the cause for majority of these codes and the rough idle.  

10 hours ago, fjh said:

yup we just did one of these! get the sensor! make sure your inlet boot is sealing on the hood just something to try for the other code

Doesn’t Mack suggest checking this by applying grease to the boot and closing the hood, then lift it up and check the print?  

See what happens once the oil pressure sending unit is changed. With those two codes that would be the one to shut it down. Something must change with heat to make it happy. 

For part numbers 14-16 they have a quantity of 2. 

Let me know if this works, it should…highlighted is what I believe all you will need. 
 

Haha, thanks. Appreciate that, I actually learn ALOT from Joey Mack, Vmac3, Glennakerstwo, fjh, and a bunch more guys on here. I’ll see about getting that part number first thing Monday morning. 

Also, all of our trucks (RDs, CVs, and GUs.) came with the water filter/conditioner and red elc from the factory…🤷🏻‍♂️

I’ll check our parts books or Mack truck portal on Monday for the part number. If for some odd reason I can’t find it there, then ill have you give me your last six and I’ll call Bergeys Truck Center and get it from them. 

Also retarding the timing on a diesel makes it easier to start and advancing the timing makes it harder. Typically when it’s really advanced. 

Awesome, I appreciate the info as usual! Should you also hear 6 clicks instead of 4 then if it’s a tandem axle? 

They are 2000-2005. You are probably right. 

I have always wondered what the clicking noises are when you turn the key to accessory and can’t find any info on it. Usually about 4 clicks on the RDs. Two in the front and two in the back. On the CVs it’s all at once. Sounds like a bunch of starter solenoids. 

Correct, as with any transmission and clutch’s. Automatics are just a little more fragile with torque output. 

Any possibility it’s idling where it needs to be and the tach is just off? Or does it noticeably sound different?

I’d say yes, being it’s essentially a boost leak. Kind of like a wastegate. Plus it will change the air fuel ratio. Probably why the idle seems different. You could have a bad actuator. Run some tests and see what you come up with. Post back with what you find and I’m sure some of the guys on here will be able to get you going in the right direction. 

Older style MP8, don’t think much has changed. This has some good info though. 
 

Could be a combination of a faulty turbo/actuator and maybe a discharge recirculation valve? Maybe the DOC is plugged up too? Hopefully some of the guys with a lot more knowledge on this can help you out. 

EGR valve could be stuck open some and 7th injector could be dirty. We had one with a bad valve and it would fail regens and the dpf was face plugged. I was told one time from someone at  Bergeys truck centers that if you take the egr pipe off that goes into the intake and if you feel pulsing/exhaust your valve is open. Just have to figure out when it should be closed to do that test. 

That’s the air compressor governor. You can try tightening it, taking it off and putting some sealer on the threads, or replace the fitting. There are plenty of options. 

6 hours ago, fjh said:

Bro (Take the advice) posted  !  Not trying to be an ass here!  But were trying to help! you need  check the fuel pressure you need to have at min 60 psi prefer a little more how ever.........!

Just sayin! 

Also remove the elbow at the primary fuel filter from the tank and check for debris in it I have seen rags fuel conditioner lid inserts and rocks stuck in this elbow! several times! just some more things to look for! This will likely show up on the fuel pressure check as low pressure when you stomp on the throttle the pressure will drop off if there is a restriction or a loose gear , where normally it would increase some!

I’m not the one looking for advice. I posted about what could possibly be going on with the fuel pump….

Yes they are, in school someone forgot to put the rod bearings in it and ran it for a good 10 min through the rpms. Another time two liners dropped and as the crank came around each time it ate more and more until the liners were gone. There were a few more “mishaps” with that poor engine but it still runs to this day from what I hear….

The gear on the pump shaft could be fine at idle and lower rpm range, but once the rpms get higher and the shaft spins faster the gear could spinning on the shaft. Could be….

Nice! Hopefully something shows up so you don’t have to keep looking and can start putting it back together… 🤞🏻