Okay here it goes.....
In the early 90s Mack released its first version of their electronics called VMAC (Vehicle Management and Control). The first generation was called VMAC1. The fuel system was a partial authority system where it had 2modules. 1 module was called the FIC (fuel Injection control module) and the other was the vmac module. Each module had their own functions, the fic controlled fueling to the pump and the vmac module controlled vehicle electronics. They both communicated via j1587 datalines. Both modules where located on the passenger side kick panel. The injection pump as JoJo mentioned was built by Robert Bosch. The FIC sent commands to the pump for fueling. There were a couple of electronic components, a rack actuator, rack position sensor and a timing event marker sensor. As JoJo mentioned the pins on the pump would get loose and had to be replaced. In the front on the pump was the timing mechanism, Mack called it the econovance. This was controlled by a actuator that allowed for oil pressure to actuate the econovance. This worked by two helical gears that would allow for advance and retarded timing. This engine was a breakthrough for Mack because now you can have specific customer data programming, better fueling and fault diagnostics.Vmac2 was the same where it was still a partial authority fuel system but with the use of 1 module. This allowed more programming features. In my opinion this was the best Mack engine ever built, 2 million was no problem for this little 12litre engine. These engine produced more hp than what was advertised. I have dynoed several of these and they produced 20% more than what was advertised. These push rod engines had two peice pistons, that werefull floating. The engine brakes were nothing to write home too. They used Jacob's engine brake and an exhaust brake that Mack called a stealth brake. Itwas an airactuatedexhaust brake that sounded like the engine was being muffled. Lifters were a flat tapped.
The new emissions standard came out in 1998 (I believe) which called for a reduction NOx and particulates. Mack introduced Vmac3, it was still an E7 engine but the engine blockwas reworked to allow for a new fuel system redesign. Mack used Robert Bosch components to make up their fuel system. They used the infamous EUP (Electronic Unit Pump) system, it is still considered to be a pump line nozzle system but each cylinder had their own individual pump that was mounted in the engine. So any cylinder to cylinder variation canbe corrected at anytime, where as the partial authority it cannot. These pumps were driven by the engine camshaft, so you can imagine how heavy this camwould be. The injectors were pretty much the same, they sat in the cylinder head in between the valves. So you may ask why did they come up with this fuel system? Well the reason is the partial authority pumps were only able to produce around 20 thousand psi of injection pressures. The eup fuel system brought it closer to 30 thousand. This is a big deal for deisel engines because when diesel fuel is injected, it is injected as a mist and not vapor. So the smaller the fuel droplet the less time is needed to compress the fuel to reach its injection pressure, inject it, heat it, turn it into a vapor and oxidize the fuel in which combustion occurs. Getting away from the science, the engine itself was the same, it was still a 12litre with a lacklustre engine brake. It was still a push rod engine with the same piston design, except the bowl of the piston was a little different. Lifters were steel rollers, then they switched to ceramic rollers with spring loaded push rods. No egr yet. The electronics gave way to a full authority fuel system, the engine ecu was mounted on the right side under the eupsand under a heat shield. Later on they moved it to the left side mounted on the intake. Mack called this engine LSR (Left side redesign).
Vmac3 had two modules the engine ecu and the vehicle ecu. The vehicle ecu was mounted on the passenger side kick panel. They both communicated via the datalinks, j1587/1708 and j1939. These are a set of languages and physical characteristics of the modules. JoJo mentioned the issues with valve trains and engine brakes with several updates they released. In 2002 mack introduced the CCRS engine Contantly Controlled Rate Shaping System). The fuel system was anle to produce a pilot injection before main injection. This allowed for lower particulates and NOx emissions. This is why these engines have a different camshaft compared to its earlier version. Mack started to loose their fame as a built proof engine, but what customers didn't realize that the grass was not greener on the other side. Most manufactures started to transition to egr/vgt engines. By late 2003 the end came for the non egr engine.
The EPA mandated for further reductions in emissions for 2004 model year. This time they especially targeted NOx, and there you have it the egr was installed on the E7 Etech engine.
ASET AC and ASET IEGR engines were introduced late 2003. Theengine was still the same e7 12 litre engine. But now they changed the camshaft, piston bowl design, turbocharger, more electronics egr system and a better engine brake. Well at least some good came out of this with their engine brakes. Really strong and enough to put you tight agianst the seat belt. The iegr engine did not have all the mumbo jumbo compared to the external egr. The iegr was fitted into offroad/construction vehicles, simply for space. The iegr used an extra bump on the exhaust lobe to push exhaust gases into the intake during the intake stroke, so the exhaust valve would open during the intake stroke. This is not new technology, Honda used this in some of their cars. Anyway the issue with these engines are they always had exhaust gasses being dumped in the cylinder and this caused a lot of grief in the beginning. Sludging of engine oil, worn rocker shafts worn pistons and liners and blow by. So Mack introduced software updates to change the fueling. Anyway no need to discuss about the external egr engine. I'm sure everyone knows about this abortion of an engine. The engine itself was good, it's just what was attached to it caused all the grief.
Sorry for the long winded post but I was walking down memorylane on this one. These engine taught me so much and it taught me how much I really did not appreciatethe original Etech engine. Looking back the Etech was an excellent engine. I'm sure I missed out on a lot of things here but thanks for allowing me to share.
V
Edited by Vmac3
