VE numbers seem high at idle .

HI- With modelled fuel If the injector flow rate input into the ecu ( link G4+ ) is higher than what they actually flow will it make the VE numbers in the fuel map artificially high ? On my map I need numbers around 72 to idle . I can still get any A/F ratio I need but the high numbers are confusing . I have the engine on a stand so can only start - idle and free rev the engine so it has me thinking what the VE numbers will get to with the engine in the car and under load and boost . Thanks - Ken

Sounds like you will need to change your master pulse width to make your ve table more accurately reflect what it should be.

Hi - Im using modelled fuel mode not traditional mode . So the numbers in the fuel map represent ( or are supposed to ) the engines air flow not the time ( ms ) the injectors are open .

One more question - I have a fuel pressure sensor connected to a AN input - Is this all I have to do for the ECU to use the input and make fuel corrections based on fuel pressure ?

Hi - thought id try and answer my own question . I backed the whole fuel table down by 50% and the injector flow rate down by 50% and voila ! Same A/F ratio with half the VE number . Seems my 1200cc @ 400 kpa injectors in fact flow less than half the advertised flow rate ! GRRRRR ! Still don't know about the fuel pressure input though .

What injectors are they? Would be nice to know.

Also, you should be able to have your fuel pressure sensor running to an analog input. Im sure you already know, but you'll have to program in your voltage slope for the sensor to work properly. I usually use 150 psi sensors from ebay, usually about 30$. Most of them use the same slope. 0.5v=0 psi, 4.5v=150 psi (or whatever the peak reading of the sensor is)

I hope that helped you out.

That is one problem with a VE modelled fuel equation - It relies on all of the data for the engine and the injectors being 100% accurate for the VE numbers to have any chance of also being accurate. I've primarily been using ID injectors and found the supplied data gives sensible VE numbers. ID also provide a short pulse width adder table which can be copied directly into the G4 ECU.

As you've found out, if the injector flow is less than the ECU thinks it is you will need to raise the VE numbers to get your target AFR and all things being equal, reducing the injector flow data in the ECU will result in the AFR moving richer and vice versa.

With the fuel pressure you need to enter the base fuel pressure you're running and then enter the rated injector flow at that pressure. If you have a fuel pressure sensor connected as well then the ECU will take any change in fuel pressure into account in it's calculations.

Hi -Thanks for that - I do have a fuel pressure sensor hooked up and used a cal table to get it calibrated and reading the same as my test gauge so it should sweet - Ta .

Hi- I had a fuel injector flow tested by a fuel injector specialist - I gave him the info sheet I got so he could do a fair apples to apples test ( Full open for 1 minute @ 4 bar and yip not quiet 1200 ccs ......... 590! Doh ! So my guess at half the advertised flow rate wasn't bad . Ok so no names at the mo because he says he,ll replace them bla bla . I hope so . With the ve based fuel mode being more popular now I hope people will only deal with reputable companies and get what they pay for because its easy to tell when the fuel map numbers don't make sense - Even to a newby . Cheers .

The VE fuel model tends to show up issues very clearly that can be disguised easily in a injection time based model. I'm a big advocate of using quality injectors from a reputable supplier who can also provide all the required data so you can do your job properly and get the srt of results you're expecting.