Z_WAAAAAZ

So I'm moving onto the next stage of laying the framework for my '95 stock engine turbo build. I currently have a DW200 fuel pump and MS3x installed and I'm planning on installing FlowForce 640 injectors next. I'm not entirely sure what to set my deadtimes to in Tunerstudio, given the fuel pressure curve on my car that I'm about to explain.

In another thread a couple months ago, I expressed that after installing the DW200, my fuel pressure at idle was around 55psi, a decent bit above the ~35psi spec for idle fuel pressure. As it sits, the stock fuel pressure regulator can't bleed off any more fuel pressure at idle. Curly was kind enough to give me some guidance and said that I could simply tune around the high pressure at idle by leaning out my idle/low load cells in TunerStudio. I went in and played with my idle VE table and low load VE cells, then autotuned the rest of my fuel map (not much changed above ~40kpa) and got the car hitting my target AFRs across the board. To reiterate, the car is currently N/A, running stock injectors, sits at 55psi of fuel pressure at idle, bleeds down to factory spec fuel pressure once at low load (~35kpa), runs great across all operating loads/conditions, and currently hits all my AFR targets.

With this in mind, should I run the dead times listed for 3.0bar or 4.0 bar (43.5psi/58psi) or should I set the dead times to somewhere in between the two and experiment with what works best? FF640 dead time chart included for reference.

Thanks in advance to anyone who has some input!
-Zak

curly

iTrader: (25)

Idle isn't very important. You can idle anywhere from 12-15afr, 10-20 degrees, 650-1500rpm.

What's more important is higher load, when afrs are more important. At these loads, you won't be running at 55psi, you'll be around factory 43.5 (3 Bar), or slightly below if you're in any vacuum, so I would enter the 3 bar settings. As I mentioned (I think) in your fuel pressure thread, this is all a compromise of running a larger pump with a factory FPR. There's probably pros/cons of using either setting, but as far as I'm aware, if you're hitting your AFR targets, that's what's important.

Z_WAAAAAZ

Thanks for the input, Curly. I'll start with the 3 bar settings and go from there. Makes more sense to tune around the pressure that I'll be at for 80% of the time rather than vice versa.

Thanks again for the help. Stoked to be one step closer to getting this thing boosted!

Z_WAAAAAZ

This probably doesn't necessitate a response but I figured I'd follow up for closure. I input the 3 bar settings for dead times and ran with those. No problem. Car started and ran fine after some minor adjustments to fueling at idle (was running lean at first). Got the AFRs pretty close to where they needed to be after a half hour of autotuning on the road. Still gotta spend some more time on the VE table but that's no big deal.

TL;DR - 3 bar settings worked fine for a DW200-equipped car with stock FPR running 55psi fuel pressure at idle.

Onto the next project.

Thanks again Curly. Lemme know if you ever wind up in SoCal, I'll buy you a beer.

Jamikins

iTrader: (1)

I have ff640s and a dw200 pump. Idle matters for my 100% street driven car. I run the higher pressure voltage curve but found a dead time of 1.3 worked well for using ac and headlights simultaneously. I do run a 13 lb flywheel. Ymmv.

Z_WAAAAAZ

Huh alright, maybe I'll experiment a bit with the dead times/curves down the road. I still have a little more fine tuning to do on my VE table to get to a solid baseline. My idle is pretty solid right now but I'm running LED headlights and deleted AC so my idle loads won't be as high as yours. Got a 9lb flywheel in mine. I'm idling smoothly at around 14-15:1 but the idle intermittently hunts a little bit when warm.

Actually you got me thinking about a quirk I've been noticing. When the car is fully warmed up and I fully let off the throttle at cruising speeds, my AFR goes full lean immediately. It'll do this before the fuel cut overrun enables and the reading will go past 18:1 where the gauge won't read it.If I open the throttle even the slightest bit, the reading will climb back to ~15:1 where it should be. Won't do it while cold, AFRs stay around 14.5:1 in the same conditions with the throttle closed. Maybe I can alleviate that by playing with the dead times...