Found an interesting read tonight. I use ROM 90550001 and there are some tables defined as the title of this post. There are about 6-7 of them, one for "starting" and the rest for "running". The article explains "wall wetting" essentially how a portion of the fuel that the injectors supply stick to surfaces such as the valves, manifold, etc.. then the fuel evaporates and re-enters the cylinder later on. conditions called snap(fast) lean/rich can occur from wall wetting and there is a function called X-TAU in most ecus to factor the amount of fuel that sticks and generate a compensation, even engine temperature is a factor due to faster evaporation rate. Im certain that the tables im talking about are compensations for this scenario. I never found much information about them and never knew what there purpose was. The article is from Megasquirt and is very information if anyone wants to check it out. Just thought id get some other opinions on the relation and your guys thoughts about it, none the less i thought it was interesting and wanted to share it. LINK - http://www.megamanual.com/ms2/xtau.htm

 

Thank you for sharing your findings about the tables related to "wall wetting" in ROM 90550001 and the concept of fuel sticking to surfaces. Wall wetting and its impact on fuel delivery and combustion are indeed important considerations in engine tuning.

The function you mentioned, X-TAU, is likely a compensatory factor that takes into account the amount of fuel that sticks to surfaces, such as valves and manifolds, during certain conditions. These compensations aim to ensure proper fuel delivery and prevent conditions like snap lean/rich that can occur when the fuel that has stuck re-enters the cylinder.

It's interesting to learn about these considerations and how they can affect engine performance. Exploring resources and articles like the one you mentioned from Megasquirt can provide valuable insights into the intricacies of engine tuning and fuel management.

If you have specific questions or want to discuss further details about these tables or engine tuning concepts, feel free to ask, and I'll do my best to assist you!

 

Thank you, im always on the hunt for more knowledge and I like to learn and keep an open mind. I just find this stuff interesting. I always wondered what those tables were for and it kinda just hit me as i was reading thru that article. X-TAU was to my understanding a matematical equation where each of the letters meant a different variable of wall wetting and used in a equation together they made a number that could be used in another equation to compensate for wall wetting in a ECU table per say. This is what you mean by factor right? my math is not that good. Mostly I have had a hard time with remembering the equations. All i know about factors is that if you have ten numbers of something, whatever it may be, you can add all ten together and divide by ten, this gives you a factor for that data. dont know what to do with the factor after that but it would be nice to know how to apply this in tuning.