steeler

You'll have to have tech tool to do a reset.

2008 MP7 start it up, runs ok but after it warms up a few minutes will start slowly developing a miss, then eventually all throw codes for #1 and #2 injectors with an fmi 5'. Kinda strange to me that this 2 injectors shut off at the exact same time.

New engine harness and tried a different ecu. Any other ideas besides replacing the 2 injectors?

Late to the party, but I was going to suggest the pump. I had one doing the same.

Glad you got it fixed!

Cracked head? If you have coolant exiting the turbo, more than likely you have coolant entering a cylinder. If not from the egr cooler, could be a head problem. Pull the oil pan and pressurize the cooling system and you should see where it's coming from. I've got an mp7 I'm rebuilding now for a leaking liner. It washed out one cylinder, but obviously I didn't have coolant in the exhaust.

On 1/28/2020 at 6:36 PM, tjc transport said:

"replaced temp sensor" there are two temp sensors. 

one on the side of the engine, and one on the back of the head at the firewall. 

The one on the side is for the temp gauge. The one in the rear is for the ecu, which controls the fan. I believe he only has the one temp sensor in the rear on an 05 though.

So the fan is only partially engaging? Do you have good air pressure to the solenoid?

Yes those compressors suck balls! 

Went ahead and did the egr cooler while the head was off, it was pretty clogged.

She's all fixed now. I hate that I pulled a damn head for an air compressor problem. Damn. Oh well I know for the next one.

Well, I ended up pulling the cups, didn't see anything so went on and pulled the head, sent it out to be checked. It all checked ok.

Put it back together, same problem! Turns out you can't eliminate the air compressor the way I've always done with older (real) macks. I removed the main air line from the compressor and problem goes away. Shoot air into the compressor at main air line and have bubbles in the coolant tank 

Air compressor replacement time, yay!

10 hours ago, fjh said:

Easier  stuff first rad cap ,  egr cooler !  Is it throwing up any  codes?

No codes. What I do with these is put a pressure tester on the coolant tank, fire it up and watch to see if the pressure builds. This one instantly started climbing, normally I don't see much pressure building until the coolant temp starts to come up.

At an idle the pressure steadily climbed to 10 psi in about 3 minutes. If I ran the rpms up it would build pressure even faster.

I've only seen this on an mp7 one other time which ended up being pitting in the head where the injector cup seats, letting compression into the cooling system. 

As far as the egr cooler, am I correct that there wouldn't even be 10 psi of pressure there at an idle? I know that it isn't leaking coolant anyway.

On 12/3/2019 at 10:58 AM, Rogerhays said:

I have a 07 Mack mp7 it will do this daily it starts and runs fine as the day goes on it will start missing I stop and shut the truck off and let it set for 2 minutes start it back up and will run fine the rest of the day. Just had an overhead done and it didn’t do it before then

All of the above advise applies here also. Very well could be that the harness is pinched between valve cover and oil valve, or bad terminals at injector.

Figure out which cylinder is the culprit first.

As far as the new harnesses having the high tension terminals, I've ran into both 04 and 07 emission new harnesses that do not have the new terminals. The last harness I changed out, I replaced the terminals before I put it on the engine. (After I confirmed it didn't have the good ones)

Common issue there, more than likely sliding clutch and gear are worn. I probably do 10 or more a year. While you at it, might as well change the syncro as well. 

No sir. Trying to finish up a couple other projects first.

Still trying to decide where to start. Pulling out cups? Pulling head? I checked the buildup of pressure with the air compressor pumping, and with it kicked out and there was no change, so I think I can rule that out.

6 hours ago, fjh said:

Egr cooler 

I don't think so in this case, it will build up to 10lbs of pressure just idling for about 3 minutes. Faster if it's idled up.

2009 mp7, what are you guys seeing as the most likely culprit for building pressure in the cooling system? This one is building quickly, literally spraying out of the overflow cap.

I know I'm probably looking at either head/gasket, injector cup or air compressor. Trying to decide which row to take here.

1 hour ago, 41chevy said:

Don't know if it will work in your application but I've cleaned solidly clogged EGR's by soaking them on Easy Off oven cleaner. Fill the port or tube fill it with the cleaner and stick verticl as you can in an.

I might just have to grab a can of that, thanks.

2 hours ago, c-mac said:

I've pulled the differential pressure sensor and used a small drill bit by hand to remove the carbon buildup in the two ports in the mounting bracket , when I figured I have cleared the mounting bracket I took a spray nozzle straw and pushed it into the venture

That's what I normally do on other applications, but this one has the ports making a 90 degree turn down inside the hole so I can't get anything to eat thru it.

I tried carb cleaner which I've had luck with in the past, but it didn't help. I just put it back together and told the customer that he will have to deal with the yellow light until the part comes in. We ordered it as unit down, which usually speeds up the process. Hopefully it won't take a month.

Exactly. I can't get anything in there to break it loose.

I sent you a message cmac.

These things are in back order till November. I've got one clogged badly. Any tricks? It looks like it can be taken apart, but I don't want to kill the truck.

On 9/3/2019 at 3:11 PM, c-mac said:

Yes it has a/c the new fan clutch is on at all times with the harness to the clutch disconnected. I’d really like to see the diagram if it shows wire number and numerical pin placement 

Sorry for the delay, crazy busy lately. I'll get that for you tomorrow!

Hopefully I can find it.

I know this is a little old, but have you fixed it? I assume the engine is an "AC" engine?

If so I have a diagram at the shop I can send you.

I agree with what these guys are telling you regarding the heater shutoff valve. Start with that.

Also, did you charge the system with the correct amount of refrigerant? If it is overcharged the higher rpm's can raise pressures too high reducing cooling.

8 minutes ago, Steve 97 said:

Ya we have one kit here just wasn’t sure if adding the oil lines would solve the problem 

I don't think I've ever successfully fixed one with just the kit, but have fixed many with kit and lines. Do both. Make sure you have the new style oil feed screws, and remove the little ball and spring from the bottom.

The kits usually had instructions in there.

We usually start with a rebuild kit and oil lines. Can you even get the rebuild kit anymore? I thought I heard they were no longer available, but I could be wrong there.

Be careful messing with the gov. 

The rule of thumb I always used when bumping them up was to screw the star wheel as far forward as it will go, then slide the plate forward about the thickness of a dime. That will make them pull stronger and dump more fuel sooner, without waiting for the boost to build.

I've never messed with the springs though.

Well I found the problem. Pin 16 on the control panel is a ground, I was getting just enough of a ground to operate everything but the compressor. So after running a new ground I have good power to the compressor, but the clutch is toast. Oh well at least it'll be working tomorrow!