Jump to content
HybridZ

Sam280Z

Members
 View Profile  See their activity

  • Posts

    395

  • Joined

  • Last visited

  • Days Won

    4

 Content Type 

Posts posted by Sam280Z

    Ms3x install

    in MegaSquirt

    Posted

     

     

    Just because you've never heard it before doesn't mean it isn't true.

    Agreed. This is why I asked for sources.

     

     

     

    The information is out there.  MS Forums if you dig deep enough,  and Forums like HP Academy, and EFI University.
    Search harder

    I've searched pretty hard and have found no confirmation of a "fudge factor" or any other claims of inaccuracy in the PW calculation, intentional or otherwise, in the calculations.

     

     

     

    You don't see any " Fudge Factor " because it's built into the software code algorithims. MS admits this themselves if you look deep enough.  I posted the PW calculator from HalTec in another thread. PW calculators have been around for decades and there are lots of accurate ones to be found online
    In my experience, Megasquirt algorithms perform "as advertised." That is, they produce results in accordance with their documentation. There are no hidden "fudge factors" to protect users from their naivety or inexperience. An overly rich condition can damage an engine just as an overly lean.
     
    I think I see the disconnect. The PW generator example you give is calculating PWs for running engine conditions. Megasquirt uses the ideal gas law to do that. (The spreadsheet you show may use the ideal gas law as well, but the formulas are hidden and password protected, so I can't easily tell.)
     
    The TunerStudio Req_Fuel generator calculates the PW (time) required to deliver a quantity of fuel to produce a stoichiometric mixture in one cylinder' volume of air at a standard atmospheric condition (1000kPa @ ~70degF IIRC).   This number is then adjusted by the megasquirt algorithm based on the amount of air the tune tells it is going into the engine (expressed as VE, or the percentage of a perfectly filled cylinder under standard conditions - looked up from the VE table) and the ideal gas law which adjusts for temperature and pressure. Again, no fudge factors, just science. 
     

     

    BTW, MS and TS are fine for what they are. A learning tool. And the price point is good. But it's a DIY experimental science project.

    I might agree with you somewhat on a MS1, but this thread is about MS3, which while relatively inexpensive, is quite capable.

    Ms3x install

    in MegaSquirt

    Posted

    But in reality, the TS Req_Fuel calculation is not accurate. Neither are the TS VE Tables. They are rough approximations... very rough approximations. That is the problem. The Req-Fuel calculations are a good 25% higher than other PW calculators estimate. This is covered in the advanced forums many times over. 

     

    MS and TS even admit to this if you search hard enough. 

     

    I find it's really annoying that they do that. It's a common complaint with Tuner studio. 

     

    I've never heard this before.

     

    Which advanced forums? Can you provide a link?

     

    I've searched and read the MSextra site religiously for the past 8 years and have never seen any mention of these issues.

     

    The Req_Fuel algorithm that TS uses is here: http://www.megamanual.com/v22manual/mfuel.htm

    I don't see any "fudge factor". What do the other PW calculators use?

     

    One thing I do know is that if you want to get a good VE table, it is critical that you have a good understanding of your injectors. You must have the correct deadtimes and voltage correction as well as the correct flow rate. (If you have exceptionally large injectors, you will need to calculate the small pw correction curve as well.) This requires testing your actual injectors with your injector drivers. That's why TS and MS provide the test modes. https://www.youtube.com/watch?v=lJgi8l-2XG4

    Ms3x install

    in MegaSquirt

    Posted

    Reqfuel is the pulse width required to provide a stoich mixture at 100% VE. It is determined by the flow rate of the injectors and the displacement of the engine. Getting it correct is essential if you ever want to change injectors and don't want to have to retune everything.

     

    VE is the proportion of air, relative to the total displacement, that is entering the engine under the defined MAP and RPM.

     

    With incorporate AFR on and a correct VE table, the fueling algorithm will essentially calculate the pw for a stoich mixture and then adjust the pw for the desired AFR. This allows you to adjust the desired AFRs without changing the parameters defining the engine characteristics.

    Ms3x install

    in MegaSquirt

    Posted · Edited by Sam280Z

    You're wiring them to the 3x injector drivers? They can fire batch or sequential.

     

    I highly recommend testing the injectors to get thier actual flow and dead time (/voltage curve). Knowing this for your injectors will make it alot easier to tune.

     

    Use the test modes in Tuner Studio

    L28 DEATH rattle!

    in Nissan L6 Forum

    Posted

    Check for slack in the timing chain. I have seen one engine that had a weird rattle similar to what you described. Turned out to be a busted keyway in the crank allowing the timing gear to slap back and forth.

    Twin cam head for the L6 from Derek at Datsunworks

    in Nissan L6 Forum

    Posted

    Not exactly $390 diff. With the pro, you also get the real time clock ($65), knock module ($85), and a registered copy of tunerstudio ($60). That's just $180 for a weatherproof product with better connectors and the additional products pre-installed (no additional work). The only downside for me is the internal sd card. Downloading logs can be time consuming.

×
×
  • Create New...