I suspect Mercedes owns the design specs while Bosch (and Doduco) just produced what MB spec'd. If so, it would be MB's fault, and Bosch simply doesn't care...
Dave, I think I would have to agree with you that Bosch doesn’t care. I wrote to Bosch in 2018 and 2020, and I didn’t get a response. As you say, no ROI.
Well, I did this improvement in an attempt to solve a repeating issue, and proved it working a couple of years ahead of the report made by Robert (
@robm.UK). However, I can't claim any rights on it and I am not hunting for big credits, but if Robert did pick up the idea from me it could be mentioned in the report. But I don't lose night sleep of this.
...
Arnt, I am sorry but I was not aware of any of your posts on the subject at the time I wrote and released the latest 2020-08-27 second edition of my CIS-e Misfire report.
When
@gerryvz made me aware of your posts on 500eboard a few months ago you will recall that I acknowledged you. But it also struck me that there had been little up-take or momentum from 500eboard.
This was probably because the idea of adding ventilation to a distributor has been around for as long as I can remember, and other Mercedes models like the M104 have slot vents around the clock and certainly at both the bottom and the top. So the concept in itself is not unique. No one here can make claim to owning this idea, so I think
@JC220 has got the wrong end of the stick.
I think you have to go back to the first page of my report, which explains the aims of my report: -
“
The purpose of this article is to ascertain the root causes of the misfiring in the CIS electronic ignition engine by measuring the physical properties of the air-vapour mixtures inside a running distributor, and through the use of psychrometric graphs and standard physics equations of enthalpy, analyse and manipulate the data collected to determine the most practicable solution to either minimise the risk of misfiring or find a permanent cure”.
What some folks probably don’t seem to appreciate is the intellectual and practical value of the report, and the fact that it is unique because it examines the root causes using novel approaches and bespoke computer modelling. This enables the size and number of vents to be reliably determined to minimise the risk of misfire in an M119 engine in most geographical locations by considering the effects and relationships of following parameters: -
Geographical location (humidity, altitude, ambient temperature)
Ventilation and effective volume of air.
Ventilation and diffusion.
Ventilation and dispersal of water vapour.
Cross flow ventilation.
Convection streams.
Effect of spinning rotor.
Effects of engine warming.
Effects of engine cooling.
Effects of variations in engine warming and cooling cycles.
Thermal gradients.
Rate of increase in temperature of the air inside the distributor cap.
Thermal inertia.
Partial and saturated vapour pressures;under varying conditions.
Moisture concentration of air inside the cap.
Dry and wet bulb temperatures.
Minimum dry bulb temperature to elicit condensation.
Dew point.
Temperature of air inside the cap.
Surface area of cap.
Density of air.
Specific heat of air.
Heating time.
Mass of air.
Effective mass of air.
Cross sectional area of existing ventilation.
Cross sectional area of proposed ventilation.
Engine RPM.
Angular velocity of camshaft.
Angular velocity of air due to rotation of the camshaft and rotor.
Enthalpy.
Heat flux.
Conductive heat energy.
Convective heat energy.
Change in temperature of air inside the distributor.
Change of temperature of surface of alloy recess.
Thermal losses.
Heat generation.
Heat diffusion.
Heat radiation off surfaces.
Heat energy of conduction through air.
Transfer of heat energy via convection.
Hygroscopic properties of synthetic and mineral fillers in the polymer.
The air volume and compactness of the design.
Imbalance in partial vapour pressures due to condensation and adsorption.
Vapour pressure equilibrium.
Vapour drive and diffusion.
Effects of high ambient relative humidity and engine cooling.
Molecular weights of water vapour, air and ozone.
Effects on rate of evaporation of condensed and adsorbed water.
Emission of blow-by of humid crankcase gases via the camshaft oil seal.
Effects of high ambient relative humidity and engine warm up.
Relationship between relative humidity and temperature of air inside the cap.
Condensation and dehumidification.
Camshaft seal, crankcase blow-by gases and gasoline fraction.
Alternative interventions - silicone / high temperature dielectric grease.
Effects of sealer sprays such as WD40.
Effect of HT voltage and temperature on silicone.
Production of silicone carbide.
Function of insulator cup.
Function of insulator rubber seal.
Function of existing vents.
Degradation of material properties over time.
Real time testing of physical properties of the air-vapour mixtures inside a running distributor.
Development of bespoke psychrometric functions and standard physics equations of enthalpy.
Detailed data analysis and interpretation.
I can run simulations to see if an M119 engine with EZL ignition and unmodified distributor caps would be susceptible to moisture related misfire in Nevada, Oregon, Florida, New South Wales, Donegal, Buckinghamshire, Lanarkshire, Oslo, Viken ... mostly any where in the world, so long as I know the ranges of ambient temperature, relative humidity and the altitude of the geographical location.
We all know Nevada is going to be low risk. It is just an example.
I can determine for each of these geographical areas the size and number of vents required to minimise misfire.
Some of the live data from my 500SL is included in the appendix to the report, but for running simulations I use a much larger database from a number of M119 engines to increase the accuracy and reliability of the results.
Regards
Rob
