Long term stuble issue.

[Puscifer]

Hey guys. As over the past month I've managed to replace my clutch / pp / flywheel / master / slave, timing / pully's / ecu / plugs / wires / MAF.. I can go on but I'm sure you all get the point (especially if you've noticed my threads).

Issue I'm running into is the car wants to stumble past 34.9% throttle opening. I figured it was the MAF (had a trouble code) - Replaced the MAF, haven't had a chance to clear the code out because Advance Auto no longer clears codes due to liability. If I hold the throttle down and let it bog out (it will never die no matter how much air i let in) i can hear the turbo spool at 1500-2000rpms - i don't like to do that, but just going into massive detail. I have 550 RC injectors w/ a untuned SAFC2 considering i have no logger at the present. I do believe some of the settings in the safc monitor have been tinkered with and i don't know how to exactly 0 everything out because i don't know the original qualities. i've tested my TPS and ICS both read on par w/ haynes. Another quality i've noticed is i'm getting about 9mpg and you could probably get high from fuel smelling the dipstick.

Fuel pump? i dunno, argueing with myself over the fact that it's dumping way to much fuel into the system for a bad pump. i've never had a dying fuel pump overdump like this. mostly starve's to lean and eventually stops. Seemed more like a AFR problem to me. But, I can hear the click from the selonoid for the fuel pump when i turn the key over, just no prime up. *shrug* i'm at a loss. My timing is dead on as i just replaced the entire timing. down to the oil pump (omfg those things are expensive)

Any suggestions? i've busted my ass troubleshooting this thing for over a month. down to the last problem i hope.

Could this possible be a big ass vacuum leak? or boost leak? I've tried to locate some of the parts for the DIY tester but i can't seem to locate the proper materials. Feed me info if you can please. Thanks in advance!

 

[TwoLiterLaser]

You have 550's and an untuned SAFC. That is your problem. If you get that SAFC working correctly, then your fuel mileage will be better, you will not be washing out your oil with gasoline, and your car will run better.

Right now you are probably just dumping those 550's unchecked into the combustion chambers. This also explains why it will run decently below 35%, at 35% the 550's are probably injecting more fuel than the system needs and hence the stumble, bad gas mileage and washed-out oil.

 

[Puscifer]

The stock MAF can't adjust enough for the 550's? I could've swore i read elsewhere that it could along w/ the stock FPR w/ a 190lph FP. it's in the 255lph FP stage that the system would start to overflow? Maybe i'm wrong or got ahold of bad information. Saying that is what left me to believe the untuned (zeroed out) SAFC2 shouldn't have an effect on the system.

In any case. I got ahold of wrong information. Any idea where I could start w/o a data logger? As I said some of the setting aren't zeroed considering i don't know what the base value's were and there's no Mass Reset function that i've noticed in the SAFC2 module. Frustrating. Please don't take it as i was argueing you're advice. I'm just open minded and the best way to troubleshoot is to add multiple factors and rule out. I don't want to sit out there with the SAFC and tweek something i shouldn't then kaboom. I finally got my clutch broke in so that opens up a bit more for me as i can now hit WOT if i need to. Anyway. hit me back boss man. Thanks for the quick response.

*edit* sorry about the first paragraph son is tugging on my sleeve and i think i misunderstood ya. so just ignore it, i'll leave it up for laughs.

 

[kenamond]

The stock injectors are 450s, and you're running 550s. If you apply 43psi to one end of each and open them for the same period of time, the 550s will let more fuel through. The ECU thinks you have smaller injectors. It thinks you need to open the 450s for a certain period of time to let the right amount of fuel into the combustion chamber, but instead, the 550s let in 25% more. That makes you run pig rich, no power, stumble, etc.

The SAFC is there to lie to the ECU so that it thinks it's getting less air flow. ECU thinks less air flow, so it opens the injectors for a shorter period of time. Tune the SAFC to the correct lie, and you get the correct AFR.

I can't tell you the exact values, but I'm almost positive you could get good starting values for an SAFC and 550s by searching or asking (something is telling me it's about 15% for 550s and 25% for 660s - but certainly don't run off thinking that's right; I'm too old for you to trust my memory). Go look around for starting trims for 550s on an SAFC or start a new thread in the tuning section titled, "Good initial SAFC trims for 550s??".

But in the end, you're playing with fire without some way to tune. Consider a logger.

Edit: Another thing I forgot to mention is that the ECU at full throttle is not looking at your O2 sensor. Partial throttle it will do this (called closed loop feedback), but at full throttle, it blindly relies on the fuel and timing maps along with the knock sensor to pull timing. In other words, the ECU cannot automatically correct for larger injectors at full throttle.

 

[Puscifer]

Thanks a ton Kena. I'm really considering a logger atm. I've been eyeballing DSMLink but it's purdy expensive, well worth the investment i've read. Any cheap alternatives other than ebay? I hate ebay with a passion. Thanks.

Can't post in the tuning forum yet =\
read the big post started by ludachris but mainly covers safc-1, not the safc-2 dead on. left outside on my chain -=D

 

[ROOKIE1]

Authentic copies of link will run the same price . A 2g maf in a 1g will come close to the correct airflow for 550 . A 1g maf flows less than a 2g . That is what you have read .

 

[Puscifer]

Got it down, up to about 19mpg with a bouncing idle. very surprising, after i tuned the safc2 up a bit (it's still not perfect but progress) my boost gauge on the dash started working. I appreciate the help again guys!

 

[Turboeagletalon]

hey if this helps these are my settings
i have a walbro 255lph, 43 psi stock fuel regulator on a secong gen car. with rc 550 cc injectors i also have my ecu chipped from dsmchips.com

you'll have to excuse the crudeness of this. it's just to give you an idea but im getting like 35mpg and still pushing 320hp firm to the ground
i have my afc set at my low throttle at 30 % and my high throttle at 60%
low settings
1000 -15
1800 -10
2200 - 10
2800 -10
- - - -10
--- -10
4200 -5
5200 0
6000 +5
7000 0 red line

your high throttle settings should
http://www.roadraceengineering.com/newafcsetting.htm

i hope this helps at all. if not i tried