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maxima injectors at 90%duty at 8psi

1021 Views 6 Replies 4 Participants Last post by  MadBad
i just got done installing some maxima 300cc injectors and at 8psi im already over running them at 90-98% duty cycle and ive got my fpr set at 60psi. so is this just strange or is there something on the megasquirt program that i didnt know to change. im just confused as to why they would max out so easily. if anyone has any ideas or has had this problem help please cause im a noob at running megasquirt.
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um... 300cc isn't much. that's about what the milennia S injectors run. depending on how much enrichment you have, 90% duty cycle doesn't sound all that far off for 8psi.

also - where you source your gauge's vac/boost supply, vs your MS source from can make a difference.. pre IC can be 1-2 psi high.. too thin a source can read a bit low... etc.
it just seems weird that the stock 220cc injectors can max out at 5-6psi, and 300cc max out at around 8psi. i guess i just thot they would handle a bit more. so when i upgrade injectors can i just continue tuning off the ve table on megasquirt or is there anything else i need to change.
Yes, Mil S injectors are 270cc and I was maxing them 90% at about 7 PSI. Nothing really seems wrong.

You should never have to change the ve table when you change injectors (maybe slightly) The value you should be changing is the Required fuel under the engine constants menu.

Click the button and run the little calculator. at 300cc it should be around 9ms (I dont know the exact number because my batts are dead on my ms laptop)
your a genious! its amazing how things work right when you put in the correct settings. after changeing the injector size my duty cycles went down to about 80% at 8psi. thanks for the help!
no problem :tup:

edit - also your fuel pressure should be at 43 psi or so.
infinity j30t and q45 have 370cc injectors, they are a bunch at junkyards
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