Can someone clarify this section of the manual please?

allen22 · Post by **allen22** » Thu Jan 19, 2006 2:45 pm

Typically, the first time someone tries to start their engine with MegaSquirt, it starts after about 5 to 15 minutes of alternating various cranking pulse widths numbers to get started (on the Enrichments page), and REQ_FUEL to keep it from stalling (on the tuning page). It may take a bit of cranking, so you might need to keep a battery charger on hand.

Once you have it started and running, let it warm-up fully, and note the injector pulse width at idle. Then you can reset the REQ_FUEL value back to its original number. It is very easy to change without having to re-enter the VE numbers. In MegaTune, go to 'Tables/VE Table/Scale VE Table' and enter your original and new REQ_FUEL values, make sure the 'Reset Req_Fuel in Constants' box is checked and click on OK. This adjusts the VE table and resets the Req_Fuel.

If you have to adjust it to keep it from stalling won't you need to leave it that way so it doesn't stall the next time you start the engine?

thanks,
allen

Bernard Fife · Post by **Bernard Fife** » Thu Jan 19, 2006 2:52 pm

Allen,

No, the idea is that you can play with the req_fuel to get started (because it's easiest to change). Suppose this takes 5.0 milliseconds to idle with an original req_fuel of 15, but it takes a req_fuel of 20 to start (at a VE of 40%).

Once you get it so it will start and run, then you can reset the req_fuel AND adjust the VE table (which is what 'Tables/VE Table/Scale VE Table' does). This resets the req_fuel to 15, but increases the VE by 1.33x, to 53%.

So when MegaTune scales the VE table, it gives you the same pulse width (5.0) you had when running before, so the fuelling is the same, the req_fuel is correct, and the engine runs fine!

Lance.

allen22 · Post by **allen22** » Thu Jan 19, 2006 3:29 pm

I think I understand, thanks!

Also, in MegaTune 2.25b715beta I can't to to
'Tables/VE Table/Scale VE Table'

After I go to Tables/VE Table 1 it just pops up a VE table. Then I can select Tools/VE Specific/Reset Req Fuel. Is this correct?

This is with no ECU connected to the PC, just playing around with MegaTune for fun.

thanks again,
allen

Bernard Fife · Post by **Bernard Fife** » Thu Jan 19, 2006 4:03 pm

Allen,

Yes, this has moved slightly in newer version of MegaTune to 'Tables/VE Table 1/Tools/VE Specific/Reset ReqFuel'. Be sure to the 'Reset ReqFuel in Constants' box is checked.

You can play around with it by changing the req_fuel and noting how the VE table changes - then you can change it back, etc.

Lance.