Fuel Flow

[thr3shold]

How is the fuel flow read out calculated in tunerstudio? I've been monitoring it and mentally calculating my mileage and it seems way off. The settings seem right, but obviously something somewhere is set up wrong. Thanks.

[LT401Vette]

Which reading are you looking at?
what firmware?

I believe there is a bug in the km/lt readout now.

[thr3shold]

TS v2.2.13 I'm talking about the Gallons/hr readout Trip/economy menu Fuel Flow - gaugeFuelFlowGallonHr

[LT401Vette]

Straight up Fuel Flow is pretty straight forward, it is calculated using net dutycycle (dutycycle less inj open time)
times rated fuel flow.

You can check to see if the tsNetDutyCycle1 OutputChannel is reading a sane value in the Real-Time display or assigning a gauge to it.

You didn't say what firmware you are using, but in 2.2.13 tsNetDutyCycle can be wrong if running sequential injection and number of squirts and alternating are not set properly.

[thr3shold]

I did, you missed it. Tuner Studio v 2.2.13. Now when you say rated injector fuel flow do you mean a single injector or rated fuel flow for all of the injectors? I do have alternating injection set up, but not sequential. I'm using a throttle body. That being said I'm not sure how you would set it up wrong, it seems pretty straight forward. Though leave it to me to find that one way.

[LT401Vette]

I did, you missed it. Tuner Studio v 2.2.13.

That is the TunerStudio version, not what firmware you are using..

If you are not sequential, it should be right.

The rated injector flow in the dialog:
Data Logging --> Performance and Economy Fields

would be for a single injector. That is multiplied by the number of injectors/cyl you have set in the Injector settings.

How is the miles/gal number looking?

[thr3shold]

My bad. firmware 2.905. The fuel flow says I should be getting 25ish, but I'm doing 18. I'm using a old laptop with no bluetooth to connect to the GPS and shadow dash doesn't have an option to display economy as far as I can tell.

[LT401Vette]

shadow dash doesn't have an option to display economy as far as I can tell.

Next release

What is your fuel pressure at compared to the rated pressure?
It has generally been quite accurate. I'm trying to think of anything that could be tripping it up, fp would for sure. I should probably add a place to enter running fp.

[thr3shold]

Yeah the fuel pressure is running high. 25 psi or so for injectors rated at 21. I was going to lower it today to see if that is the issue, I just don't see how that small amount is going to sway the mileage figures so much, but we'll see. I've had a lot of problems with this install so I wanted to check my assumptions regarding the software before I continue troubleshooting the hardware. Thanks.

[LT401Vette]

25 psi on injectors rated for 21 would mean it is actually flowing 9.1% more fuel.

You could increase the injector size by 9.1% and it should be correct..

But that 9.1% doesn't account for the variance you are seeing.

Also is it TB injection? Why is the pressure so low?

[thr3shold]

I'm using a holley pro-jection 2d set up and the replacement injectors are flow rated at 21psi (81.6 lbs/hr @ 21 psi) so that is what I was going to run.