MXS Hot Codes

I might be wrong but what I have understood they change intake cam timing. That is like VTEC in Honda and VANOS in BMW, it's used to get wider torque curve. Intake valves advanced is usually good for low rpm and retarded for high rpm. BUT, in these low NOX engines it might be used for something else that is not good for power or fuel mileage. All these new techniques except EGR,SCR and DPF could be used to make really big horsepower if you just could program the ECM the way you wanted.

 

You are correct about intake cam timing changing. They do have a different camshaft, but the intake actuator controls the closing of the intake valve, giving the closing timing control to the ecm. You can feel the actuators when they come on, and watch the hp drop a bit on the dyno.

 

I have a 550hp MXS (2006)yr. in a customers T800 kenworth running with the IVAs disabled,and he didnt notice an increase in hp,only thing he noticed is it doesnt smoke anymore (it had hot fuel settings).The IVAs keep the valves open longer the higher the load is on the engine the longer it keeps the valves open to reduce the compression down from 18:1,but they use the intake valves so that hot compressed air goes back into the intake,and that air actually slows the burn on combustion.I think IVAs are a good thing for performance,but would'nt it be better if they used the exhaust valves.Hot air in intake is bad.

 

I have an 2006 MSX 475 in a 07 Pete pulling a flatbed getting around 5 mpg. I've seen my mileage go all over the place from 4.5 to 6.2. The ECM lifetime mileage is 5.57. I know pulling a flat is not like pulling a van but I think it should do better than what its doing. The power is there for a stock MXS but I know that could be better also. Its done had 2 intake valve actuators replaced (#4 & 6)and getting ready to replace another one(#2(its comming and going). After putting the fuel temp wire on the power was better, put the boost wire on and didnt notice much differece other than the extra smoke and and my fuel soot level went from .02 to .04 in 10000 miles so I took that off. I have noticed the haver the load the better it runs if I'm not in a strong head wind, if I am you can forget fuel mileage.

By the way....A BIG THINK YOU to DDS, CaterpillarWrench and all the other Cat guro's on here.

 

Keeping intake valves open too long is called Millers cycle, it has some benefits but I dont remember what and if I remember right it is usually used in mechanical compressor equipped engines(like Roots blower). I think it's not Miller cycle they are after in these low NOX engines.

 

No,that is the sad thing,they are not after performance.The hot compressed air from the intake valve held open on compression stroke gets pulled into the next cylinder on intake stroke,and that hot compressed air does essentially the same thing as egr,it slows the burn in the cylinder,thereby lowering NOX.I am just trying to figure out if we can use all this technology for a GOOD reason.

 

If those mains were only a year old, and shot, I'd be looking for the reason! I'm not a mechanic, but that sounds VERY premature; severe service, Very severe service, or some sort of defect. And for the oil analysis not to pick up on that is puzzling also.

GOOD LUCK

 

Studied Wiki after writing last post, I think it is Miller cycle Cat is after.

In a typical spark ignition engine, the Miller cycle yields an additional benefit. The intake air is first compressed by the supercharger and then cooled by an intercooler. This lower intake charge temperature, combined with the lower compression of the intake stroke, yields a lower final charge temperature than would be obtained by simply increasing the compression of the piston. This allows ignition timing to be advanced beyond what is normally allowed before the onset of detonation, thus increasing the overall efficiency still further.
An additional advantage of the lower final charge temperature is that the emission of NOx in diesel engines is decreased, which is an important design parameter in large diesel engines on board ships and power plants.
To this end, successful production engines using this cycle have typically used variable valve timing to effectively switch off the Miller cycle in regions of operation where it does not offer an advantage.