M1088a1 problems

[reb87]

I am having some issues with my m1088a1 with cat 3126. Several years ago the engine quit while I was driving it and it sat a couple years before I had a local mechanic look at it. He ended up putting a new computer and high pressure fuel pump in it. I am capable of working on stuff but modern electronic trouble shooting is out of my comfort zone. I am using this truck for farm and need it right now to get some grain hauled before harvest. After the mechanic put a new ecm and pump in my charging system quit working. I ended up putting a 24v alt on and used a 12v converter. That has worked well. The engine retard feature never worked after the new computer, the speedometer is reading exactly double the speed I am going(40 mph actual shows 80) the hi/lo idle switch doesn’t work. I asked the mechanic if he could program it to fix these issues and he seemed hesitant. I decided to live with it and have used it a couple years. Yesterday while hauling corn it was hesitating as I was driving. I changed both fuel filters and took another load in. It had good power but would occasionally lose power or stall when I tried to accelerate. It acted like it had a plugged fuel filter. I don’t understand anything about how to scan/programming, what equipment I need to do so etc. I’m wondering if I need to take it back to the mechanic to have it scanned, if so can someone post what he needs to do to program it to work with the retard and speedometer? Do I need to bit e the bullet and buy a programmer and learn how to use it? My other trucks are m915a1 and m920, m818. This truck’s electronics scare me, HELP.

 

[GeneralDisorder]

The "mechanic" put the wrong program on the ECM. These trucks use military specific ECM programming. Sounds like he doesn't have access to CAT SIS or doesn't understand that the ECM need to be programmed with the correct flash file per the engine serial number and then the military specific changes have to be made for the speedometer pulse per mile, etc.

In addition, your symtoms are most likely what I have termed "Transducer Rot" - all of these 3126 and C7 engines have failing transducers for the boost pressure, atmospheric pressure transducer, and HEUI injection pressure transducer (and oil pressure on the C7). They routinely fail on these trucks and should be replaced if they have not.

I can program the ECM for you - I program these for our community regularly. Turn-around is a couple days for shipping but if you have a new ECM we can flash a military program to it

 

[NDT]

Get your 915 going! 1000 times more reliable than 1088.

 

[reb87]

they are going, I just need the 1088a1 going also

 

[reb87]

Looks like I need sensors:
194-6722 atmospheric
194-6723 Boost
194-6726 Heui
Those numbers look right?

 

[hike]

I too knew nothing about vehicle electronics when we bought our M1078A1. @GeneralDisorder convinced me to buy electronic diagnostic kit. With a bit of trial and plenty of errors we have solved issues in our ABS, reprogrammed CTIS, diagnosed HEUI pump issues and learned how to better monitor the engine and transmission.

GeneralDisorder reprogrammed our ECM from 275hp to to 330hp and is a wealth of knowledge. I'd look into purchasing the diagnostics and obtaining the military softwares to check, test, and monitor the various systems. Once you start it begins to all come together removing the guess work—

 

[ckouba]

I too knew nothing about vehicle electronics when we bought our M1078A1. @GeneralDisorder convinced me to buy electronic diagnostic kit. With a bit of trial and plenty of errors we have solved issues in our ABS, reprogrammed CTIS, diagnosed HEUI pump issues and learned how to better monitor the engine and transmission.

+1

I'm as cheap as the next guy, but was very happy to have the diag kit and laptop when I had my HEUI issue. Is the kit + laptop expensive? Depends. In the one time I needed to use it on the road, it saved me on both the shop bill and waiting for time in their schedule to work me in. I went in with the data and talked with the mechanic. I may have spent a few hundred $'s getting set up, but in that one event, it paid for itself.

Having it around to monitor and diagnose as needed is also worth the price of admission, even if I don't do it much.

 

[Ronmar]

Yep, it is like having a basic scan tool on any other modern auto when it throws a check engine light or starts behaving erratically… without the reader, you have little idea what is going on…