thatv35guy

iTrader: (1)

So, I just fixed my fuel pressure issue (after installing a CJM Stage 1 RFS, DW 1000cc injectors, and Walbro 485 fuel pump, I couldn’t get the fuel pressure at idle below 60 psi; drilling out the swirl jet to .100” (#38 drill bit) seemed to have solved the issue) but after I lowered the fuel pressure from 61 psi to 51 psi the car’s running much richer (AFR’s in the 9’s-10’s)… when I increase the fuel pressure the car starts to lean out where it needs to be…

Any thoughts? I’d figure it’d be the opposite...

str8dum1

iTrader: (11)

Are you adjusting the fuel pressure setting in the software each time you adjust your regulator.

thatv35guy

iTrader: (1)

No… What? I havn’t changed anything on the software since I was able to lower the fuel pressure… can you elaborate?

phunk2

are you sure it wasnt in cold start when you first started it, and by the time you raised pressure the engine was warming up and leaving cold start and going into closed loop?

thatv35guy

iTrader: (1)

I don’t think so… I tried raising and lowering the fuel pressure when the engine was at normal operating temperature and I had the same result.

phunk2

Well... its an EMS/logging related issue, that is for certain.

Because lower fuel pressure will obviously result in less fuel then higher fuel pressure at the same injector pulsewidth, no way around that. So the injector duty cycle has to be changing as you change fuel pressure for it be able to go in the opposite direction.

Either your EMS has a fuel pressure sensor and some type of compensation table based on it that is working backwords, or your closed loop fueling is acting goofy, or your wideband sensor isnt reading correctly. Or perhaps there is an exhaust leak giving you incorrect A/F readings.

Also, you talking about just idle only or the entire powerband? Are you running the vacuum line or no vacuum line on the regulator? Are you setting the pressure at idle with vacuum line connected, or are you setting base pressure with no vacuum line on the regulator?

thatv35guy

iTrader: (1)

Yeah, I think you’re right. I’m just going to try to make the adjustments that Rich mentioned about and try to get the AFR to a reasonable level and then I’ll just get the car out to ProEFI this week.

Edit: On a side note, I also finished hardwiring the fuel pump at the same time…

phunk2

If you set the regulator to 52psi with no vacuum line, it will run exactly how it did before the fuel system, minus possibly a little richer towards redline if the previous tune had a fuel pressure drop on top.

Then you can connect the vacuum line and adjust pressure when on the dyno to tune it.

phunk2

The hard wiring fuel pump wont effect the A/F as the pressure in the rails is the result of the entire fuel delivery system combined. What the injectors do with that pressure is up to the EMS!

str8dum1

iTrader: (11)

Ok so you want to start from the beginning.

Unhook vacuum from the FPR. Loosen the FPR to determine what is the lowest FPR you can run. If its under 38psi, set the regulator to 43.5psi. Otherwise, set the FPR to 5psi higher than the lowest psi you can control.

Then input that fuel pressure value into "primary base fuel pressure"

Reconnect the vacuum line.

You also need to change the "fuel system type" to "return" not returnless like you have selected.

Anytime you change the FPR at the regulator, you need to repeat all the above steps, so that the software is calibrated for the actual FP its expecting. Injector pulsewidth is fuel pressure compensated, so you gotta have your tables right.


Assuming your VE map was good before changing injectors, you can adjust your "injector offset" to reach your idle AFR targets. IE, you find that you are richer or leaner, you can adjust that offset up or down to get your AFR back on target.

you should not have to mess with your VE table if it was dialed in properly.

***also, is that a screen shot from your actual map? Where are injector 4,5,6 outputs?????