samnavy

iTrader: (7)

I'd been running 1.8's w/no restrictor in the boost line to my Begi AFPR with the adjustment needle backed all the way out, getting me the lowest fuel pressure I could, which was right aroun 100psi. The car was a rocket.

In anticipation of NE Dyno-Day, I've installed the small plastic restrictor and the green-top 305's. I went for a short but spirited drive. The problem is that I can't see the fuel pressure gauge as it's in the engine bay. I'm going to get some fittings and hose so I can run it through the cowl so I can see it through the windshield. But in the meantime...

It feels choppy in the lower gears, like it's hesitating a little. I've lost most of my "oomph" in 4th and 5th, like I'm dragging an anchor. It's not stumbling so much as just rough. There's no knock... in fact, I've never heard this car knock... ever. But what I'm describing is classic rich symptoms, right?

For you AFPR guys, how much is fuel pressure effected by each turn on the adjustment needle.

I also cleaned and painted my fuel rail while it was out.

t25miata

Do you need a fuel pressure riser with 305s? I run 8-9 PSI with the stock fuel pump and 305s and get no ping, in fact, it is rich like you describe...

t25miata

So, my question is, what boost do you run?

samnavy

iTrader: (7)

Hmmm... that's interesting. Spiking to 11psi at around 4500rpm, then dropping off to 9-9.5 by redline. I just took another look at the directions for the Begi 2025 AFPR and I'm doing everything right.

I have backed out the needle valve as far as it will go and I'm still getting the sluggish response above about 5psi. It pulls mostly like normal up to around 5psi... but with any more boost, no more power. It starts to stutter and if anything, loses power. This happens in every gear. It just defies my knowledge of how this thing works that with the valve fully open I would have too much pressure.

I really need to be able to see the fuel pressure while driving. Maybe that's a Sunday project. I was thinking of just turning up the boost a little. More air will lean it out.

Any thoughts?

Ben

iTrader: (33)

Are you running the BEGi supplied check valve off the needle valve? It's very restrictive and doesn't allow a good bleed off.

I am running a dual check valve system comprised of the BEGi supplied check after a Autozone supplied check valve with a built in T.

Below pic and graph are older, from back when I was running 1.8 265s. You can see that I could not bleed enough still at higher RPM. Perhaps teh 305s are just too large, but first try removing or moding your CV.

samnavy

iTrader: (7)

Hmmm... never thought of that... never heard of that.
OK, that's another project for tomorrow.

In anticipation of MSpnp, I'm investing shortly in an LC1, might get it this week, but probably not be installed prior to NEDD. I can always throw the 1.8's back in and remove the restrictor.

Braineack

iTrader: (62)

lean will feel like it cant go anywhere, like there is absolutely no engine....you'll feel it hesititate like you're hitting a rev limiter.

rich, will feel like the car is boggy and almost farty out the tail pipes...it will go, but it will drive, but it will feel like a tank.

Mechazawa

I ditched the begi check valve long ago. I use a brake booster check valve from a Toyota, frankly even that won't be enough at higher boost. I am considering going to a duel bleed valve arrangement.

Braineack

iTrader: (62)

Let's see if I can't convince him to go Megasquirt next weekend in DE.

samnavy

iTrader: (7)

^You're not gonna have to try very hard. I've ditched the idea of LM1 altogether for LC1. I've got all these leftorver DSM parts that are going on DSMTrader today, plus what I can probably get for my current fuel/spark stuff will pay for it.
I'm still a chicken... just gonna wait for a few other people to work all the bugs out first and then I'm in.

*Bright light!*
Gonna go for a drive on the 305's (on the way to Advance for a check-valve) with the restrictor removed... see if that changes anything.

Mach929

iTrader: (3)

the other day i installed my rx7 afm and set my emanage correction to 0, took about 10 minutes to get it to run perfect, smoother than it's been since i took out the stock injectors. Got idle right where i wanted it with the internal spring but was getting a rich cruise, backed the adjustment screw out about half way now it's perfect.

Braineack

iTrader: (62)

yeah exactly what I did, offset the cost completely. It wasn't even that bad getting it setup. I had wiring issue's due to DIY's instructions, but once it was wired up, it was pretty much turn-key. Take a look at these pulls...gives you an idea of how good it can control the AFR.

samnavy

iTrader: (7)

I removed the restrictor and MY POWER IS BACK! So whaddya know, it looks like I was running lean. I bought a new check valve to add to the extisting Begi one, but before installing I have a ???

The check valve is supposed to slowly bleed the air out of the top of the AFPR, keeping the fuel pressure from skyrocketing during higher boost, right? However, I just found out that my problem was that I was running lean, because removing the restrictor (raising my fuel pressure back up) brought my power back. Won't adding the second check valve bleed off pressure at an increased rate and reduce fuel pressure again, causing me to run lean again?

The way I understand it (and I've gotta trust Corky here), is that (with my relatively low 10psi boost) the Begi 2025 AFPR is supposed to be used WITH the restrictor and WITH their supplied check valve. And that with my Walbro 190hp should be able to adjust between like 60-130psi at whatever boost. Without the restrictor I was unable to tune lower than 90psi, which my 1.8 injectors like very much at 10psi. With the restrictor, I haven't been able to verify my fuel pressure, but even at its max rate of rise, I was running too lean as it turns out, so well less than 90psi.

I am currently running the same setting (no restrictor and needle valve full out for 90psi fuel pressure at 10psi boost) with my 305's and I notice no change in the power delivery. Going from my 254cc tan-top 1.8's to my green-top 305's made ZERO change in how the car feels at 10psi.

So, what will adding the second check valve now do for me? My feeling is that it will bleed off enough boost inside the AFPR that I won't get the full 90psi I was seeing and I'll run lean again... then I'll have to turn the needle in and raise the Fuel Pressure until my power comes back? I sure as hell don't want to run WITH the restrictor and WITH the second valve, right?

Damn, I really need wideband! WIDEOPENTUNING, DID YOU GET MY PM???

Braineack

iTrader: (62)

we'll have that fuel pressure gauge you sent me up there to verify pressures if need be.

SamS

iTrader: (2)

WOT sold me the wideband instead, sorry bro. :gay:

Ben

iTrader: (33)

Before double check valve, 265cc tan tops & walbro




After double check valve, 265cc tan tops & walbro



You can see that either way, it's rich after 6k rpm with the 265s, but at least it's on the charts rich with the extra bleed, where without it was richer than the wb can read. Your 305s are going to be even worse.

FHS

iTrader: (2)

Check the tailpipe and area immediatly around it. If you're running rich, you'll see black soot caked on the rear bumper. Hell, when I'm running rich, I can see black smoke pouring from the my tailpipe in the rearview.

samnavy

iTrader: (7)

^We're well past that. I already discovered in post #13 that I was running lean. And w/o a cat, I always have black soot.

Brain, I've got a FP gauge installed, it's just down on my dual feed line so I can't see it while driving, but visible when on the dyno. I've got to add a section of hose so I can peek is out from under the cowl so I can watch it while driving.

Ben, that graph totally stumps what I thought I new about turbo'ing this car. I'm not smart enough to do the math in Brain's FAQ, but I've got a lot more room here to turn up the boost, and it seems nowhere near needing 305's. What key piece of knowledge am I missing?

I'm gonna swap back in the 1.8's, install the check valve, and leave the restrictor out. I'll save the 305's as my initial injectors for MS.

Braineack

iTrader: (62)

FWIW, I couldn't make a lot of boost on my tan tops.






verus 11psi on 305s:

Ben

iTrader: (33)

The formulas come from RCEng. And they are super conservative in relation to quantity of fuel per power, especially considering that they have to leave a huge margin for "real" dynos (while we all use cheater dynos) and overall safety. I've never checked, but I wonder if their higher flowing injectors come at a higher price than lower flowing ones? Also, when you're doing the math, everyone recommneds not exceeding 80% injector duty cycle, but from looking at EMU datalogs, I've seen the stock ecu run the injectors at 93-94%. Considering that they're at 100+ psi fuel pressure at >90% DC, consider them to be static open.

It's my humble opinion that any injector larger than the 1.8s should not be ran without some sort of piggy that can both add and remove injector DC. There are many running 300-320 cc injectors with a piggy and NO FMU.

Not a bad plan. Right now (since the dp upgrade) I'm running the stock 1.6 injectors, walbro, BEGi FMU, no restrictor, and double checks, and have plenty of fuel for 7 psi (diy ball and spring MBC). I'm still appx 11:1 through boost, and it's got to be making 170-180 at the wheels. That's with the 205cc blue tops. I did *not* have enough fuel for a 15psi spike settling to 10 psi no matter how much FP I ran though (Forge MBC on its lowest setting).

I have some NB 1.8 "thin body" injectors I got from Skip Cannon here waiting. If the MS guys don't respond to my email tomorrow, I'm going to put them in and see what I can do. I'd expect to be able to run them to 12-13 psi, hopefully 220-230 rwhp or so. I'm not going over that just because I don't have real timing control, but Tom got them to just under 250 rwhp.