help with tuning after upgrading injectors

[materchan]

i went from my stock turbo injectors to mercedes 036 injectors. and when i plug in the required fuel in the MS constants it gives me 8ms for the required fuel. running 14.7afr. and when i started her up for the first time it hardly ran. i ended setting the required fuel down to 5.5 where it idled nicely. i upgraded the fuel pump too so the injectors are getting the required fuel. i havnt driven the car yet, but i will soon then i will get a log of whats happening. i thought all i needed to do was to change the required fuel and that would be it.

 

any help here would be great, thanks.

[trippintl0]

make sure the fuel pressure is normal, my fpr went bad (stock) and was giving about 58 psi of fuel instead of 36.

[mobythevan]

What I saw when I upgrade from stock injectors to 450cc injectors was that the required fuel value changed like it was suppose to, but the table around idle had to be re-tuned becasue the bigger injectors deliver too much fuel at idle because of their minimum open time. If you make it idle by messing with required fuel, then the rest of the VE table has to be re-tuned.

[materchan]

thanks, ill give that a try.

[z-ya]

Increase the required fuel (RF) number by the same percentage as the injector flow rate increase. This should get it started. Then fine tune the idle using the RF setting once the engine is warmed up. You may need to make changes to your VE table, but scaling the RF will get you close enough to start VE table tuning.

 

When I upgraded from 19lb to 26lb all I needed to change was the RF, the VE table was still close enough.

 

New_RF = Old_RF + Old_RF x ((new_flowrate - old_flowrate)/old_flowrate)

 

Pete