s2000Junky

Duty cycle is the spray pulse width/duration of the injector. So the % is only the residual of your ecu settings, in other words there is no cap like fuel pressure. Fuel pressure will determine how much fuel gets injected into that pulse width, which would also add fuel, but mechanically rather then digitally. So if your tapped out on fuel pressure because of an undersized pump, yet are only seeing 75% duty cycle in your logs because of your fuel table settings, then clearly adding more fuel in the program setting is what's needed.

In an extreme case for example, you might have an injector that is capable of running at 100psi and 100% duty, but if your fuel pump cant deliver the amount of flow strength to pressurize your system to meet those demands then your tune will do exactly what's its doing in this case, which is to lean out once that threshold is met. To allow more fuel to the engine, backing off the pressure and increasing the duration aka pulse width of the injector is how you do that. Fuel pressure increase should only be used after the injector pulse width is maximized to reasonable headroom levels for changes in running conditions to where the ecu may need to up the pulse width for enrichment. Generally 80% duty is the target. But not a rule, and if your on the cusp of fuel delivery, balancing a slightly higher duty and or fuel pressure to bring you back to nominal levels is fine, if the alternative is investing in a whole new fuel system to where that investment may not have been really needed. Learn to maximize what you have before you go spending more money is my wave of thought. The right size fuel pump is important. I would not run less then a 340 in my experience pushing well past 400whp and ID1000. ID1000 are great injectors which will run good on really high pressures, but you got to be able to get the fuel to them first.

liquid_helix136

Soooooo

I was putting a towel over the pump to muffle the noise tonight (while the car was running) and as soon as I hit one of the wires back there, the pump lost connection somewhere and the car died. At first I was like "oh f@#k" so I checked all the connections, hoped for the best and fired the car up. Everything was fine, I wiggled all the wires, tugged on some connections, everything seems fine now. Weird.

So I drive home and the AFRs are all kinda rich. So I decide to give it a 3rd gear pull... Normally it is in the low 12s then leans out to high 13s, well now its in the mid 11s and goes into the 10s at redline..

Sooo seems like everything is fine now. The pump is a lot queter now too, there must have been a bad connection causing the fuel pump to stress, making it less efficient or something. I'm gonna redo all the wiring to prevent anything weird from occurring again.

Those damn confounding variables. Yay for towels.

liquid_helix136

Drove the shit out of the car tonight. Omg its amazing. The tune is so good, afrs are perfect, car has great power everywhere. This is how it should have come from the factory. Its amazing to truly feel satisfied with the tune, drive the hell out of it and it feel amazing.

s2000Junky

Right on What about your timing issue now? I new it was likely something related to pump delivery, based on your symptom. Hopefully its not the pump itself, you never know with those walboro 255's.

There used to be Chinese knock offs floating around out there which had inferior plastic innards, not sure if thats still a problem these days. I wont ever run one again myself since the advent of the quiet and higher capacity 340 series pumps from the newer companies that came on market over the last 5 years or so. Ive been running the same FB340 in my car for about 5 years when I was boosted and now back to NA. Im actually in the middle of performing the sos re wiring for it since im tapping out on the fuel pressure i need NA with stock injectors. Im not getting all the pump can offer with inferior old factory wiring. I need it more now that I no longer have the ability to increase injector duty.

DaGou

Well glad Liquid got his shit together and fixed his inferior wiring, lol no really, glad you running great again. I would feel bad knowing that you spent the time and the money on the FST and you were no better off then when you started.

S2000Junky, please do not think I am being argumentative I am just trying to get a better understanding. There is one thing you state above that loses me(not hard to do).

"So if your tapped out on fuel pressure because of an undersized pump, yet are only seeing 75% duty cycle in your logs because of your fuel table settings, then clearly adding more fuel in the program setting is what's needed."

Using Liquid's experience here; He was tapped out, he added more fuel to his table and was still tapped out. Why don't the injectors compensate and stay open longer to add more fuel? Simply put what prevented the duty cycle from increasing higher than 75%?

liquid_helix136

I think me purchasing the walbro 255 was an oversight frankly. I saw they offered the AEM 340 with the FST and for whatever reason ruled it out. I knew the 255 would deliver plenty of fuel, and I guess I assumed it being enclosed in a tank, it wouldnt be too loud. I'm retrospect I definitey should have done the 340 pump. I've still got the 340 aeromotive in the main tank, but its now effectively doing nothing but pumping fuel to the FST. Hopefully neither pumps burn out and I have happy boosting.
Last thing I need to do is order a rear tray (mines missing) and maybe a bit of dynamat to put on the underside of the tray to hopefully quiet down the cabin a bit.

liquid_helix136

As for the timing issue, I'm gonna take some datalogs and see if it's still retarding ignition with the fuel being in range now.

s2000Junky

In other words, im saying to add injector duty rather then fuel pressure. I think his thinking was that too much duty is bad, when in fact you can run 100% if you had to. But you will be hard pressed to get 100psi to an injector and have a good atomize fuel at all rpm ranges and duty requirements smoothly. The way I understood what he did, was he backed off the injector duty and then increased the fuel pressure to try and remedy the lean condition. When that effectively put more strain/duty on the suspected tapped out pump to deliver fuel, where as increasing duty cycle on the injector and backing off the fuel pressure would have been the more sound course of action to remedy the problem. But thats all based on the premise that the pump is getting proper voltage and delivering a consistent flow that can supply the injectors to begin with, which sounds like it wasn't. Either way the pump wasn't able to supply the injectors for the demand. But increasing the pulse width on the injector puts far less demand on the pump then asking an increase of pressure from it.

If your getting proper voltage on both a 255 and a 340 so they can in theory both deliver their rated flow rate at say 95psi for example. The 340 is going to deliver more flow capacity at the same pressure. Which means it can supply fuel to a larger injector, when/IF called upon by engine demands/fuel table program settings for injector pulse width.

There are actually mathematical calculations to properly size your fuel system ie; injector size, fuel pump size and fuel pressure to run, for an engine build expecting to make X amount of hp. Doesn't matter how many pistons the car has or what its displacement is. X amount of hp production means it consumes x amount of air/cfm and therefore requires a exact ratio of fuel delivery to mix with that air for a proper safe fuel ratio.

s2000Junky

Good, be curious to see if your proper fueling rectified that or not, or if you have something unrelated going on. I suspect the timing retard seen was in reaction to lack of fuel the ecu was seeing, and some form of corrective measure was being either cued in intentionally through program settings, or reactionary through your engine detonating from running too lean. I can only speculate, since I dont have access to all your tuning parameters either you or your previous tuner have in place. If the timing retard is related to the fuel starvation, I hope it was preemptive threshold setting rather then post response form actual detonation being read.

liquid_helix136

I found the problem with the electrical. It wasn't any of the wiring we did on install, it was actually the Radium Engineering supplied pinned harness to power the whole unit. The pins weren't making the best contact with the unit, if I moved the harness a certain direction, the pump would lose power and the car would die entirely. I repinned the connector, plugged it in and all is well now.

The timing actually ended up being an oversight in the tune for my soft rev limiter Since Hondata uses a mix of the 4 surrounding cells when applying fuel / ignition tables, at higher rpms, half the cells would hit my soft limiter setting, which is -12* of timing, causing the timing to creep down as the rpms got closer and closer to 8500. I added some load points in between my limiter and my ignition settings so that wont happen anymore. Timing holds strong untill the last 50-100 rpms which is how I want it.