MicroSquirt.com read only forum (Jan.15,2018)

All (and Bruce/Al/Lance if available),

I installed my Carb-to-EFI equipment earlier this week and durring a two-day hiatus from the project I have done so much reading of the Tuning Manual that my eye sockets are leaking blood. This has given me time to stew over the start-up procedure in the Tuning Manual and commit it to memory. If you guys have a chance can you please comment (or verify) the procedure below?

1) Generate VE map (or in this case Lance was kind enough to give me his VE map for his 408 smallblock chevy - which should be similar to the one I need to use for my highly modified 355 smallblock)

2) Set the constants and generate a theoretical REQ_FUEL value via the Megatune tool.

3) Open up the "Warm-up Wizard" (I am using Megatune 2.25 with MSnS-e ver. 024s9) and tinker with the cranking pulsewidths to bring the engine to life.

4) Once the engine gets to the point where it starts and then dies shortly afterward I should tinker with the REQ_FUEL value in the "Constants" page to keep it running. (Or rather alter the REQ_FUEL value beyond what was initially calculated via the tool).

5) Once running let the engine warm up to full temperature (~200 degF in my case).

6) Tinker with the VE table in the areas corresponding to idle and dial in the throttle stop and idle speed/mixture/MAP

6) Tinker with the Accel enrichments and/or Warmup enrichments (though being that the engine is already at temperature I would be more inclined to toy with the Accel enrichments first and then the Warmup enrichments after I let the engine cool down)

Does this sound correct for the time being?

Question 1: The tuning manual states that after the engine is started and warmed up I should take the initial REQ_FUEL value that Megatune calculated, and the REQ_FUEL value that the engine is currently running on, and then scale my VE map accordingly (via the "Reset ReqFuel" tool in "Fuel Table1+3 - VE Table 1 - Tools - VE Specific - Reset ReqFuel"). However, if I use Lance's VE map do I still need to scale the map? My understanding of the situation is that the scaling of the VE map is relative to the map generated in Megatune and therefore would not apply to an already "dialed in" map - in this case Lance's. Am I correct?

Question 2: (and I apologize if this question is in the wrong forum) The software I am currently using is Megatune 2.25 with MSnS-e 024s9 (fuel control only at this point by virtue of the 12x12 VE table). Can you please recommend the appropriate Megatune and MSnS-e versions that I should be using? I built my MSEFI computer in the later part of 2005 and have been tinkering with it since - so I am going to wipe everything off and start from scratch with the appropriate software versions. This is mainly just for peace of mind and to get everything on the right page. I also got a couple of errors from Megatune 2.25 that don't seem to effect anything per-say, but nonetheless would like to make sure that I am using a proven/matched software combo before I start on long-distance trials.

Any and all information would be greatly appreciated! ETA on the start-up is tomorrow @ 12:00pm.

Thanks again all!!

- Jesse

Grab the 029q2 version of the MS1/Extra software and latest 2.25 release of Megatune.
See http://megasquirt.sourceforge.net/extra/setup.html

Sounds like you've done your homework on startup procedure. Even though you have a close VE table, you will still need to do your own tuning to accomodate your own engine.

A note on entering the details - make sure you either tune while connected to Megasquirt, OR load in a default file (provided with 029q2) first and then later burn it to Megasquirt.
If instead you opened Megatune offline with the tables all zero you are going to have problems when you send that to the Megasquirt.

James

Thanks much!!!

You are right; I will need to do a little more tuning on the VE map after I get it running. My rationale is that since Lance's VE map is based around an engine a bit larger than mine (alebit from the same family of engines) the A/F ratios will be a bit rich. This is good since I would rather approach the optimal VE values from the rich side than start lean and shatter my forged pistons. (Hopefully the values won't be so rich that they confuse the hell out of Megatune. Do you happen to know to what extent Lance has modified his 408?)

Again, thank you for the input!

At low loads (like idle) you are extremely unlikely to damage the engine even with a very bad tune. Full throttle under load is when damage can occur.

Provided you take tuning in a stepwise manner and go easy on the throttle until it is safe you should be fine.

The "ReqFuel" should already compensate for displacement and injector differences. So I wouldn't necessarily expect your engine to run rich because you used Lance's table.

James

WOOO HOOOO!

After 3 years of research and 1 year of hoarding parts my MSEFI install is finally finished and running (beautifully I might add). It is night and day difference between the MSEFI unit and my old Holley 4-Barrel!

I would like to thank Al, Bruce, Lance, and all those who helped me in getting this project finished. THe MSEFI unit is a fine piece of engineering!!

And without further delay....here is the datalog of the unit as I was it was making its maiden 100 mile trip. (No, the datalog isn't over the entire 100 mile trip; just a fraction of it. But I swear, there is nothing like getting the EFI system running and then looking at the datalog of the performance afterward!)

Thanks again everyone for all the great support!!

- Jesse

Congrats, Jesse!