mamurra2

Has anyone gotten this combination to work? I'm fine at low load stuff, ~14.7:1 @ idle and cruise. But when I go to WOT my a/f's are bouncing between off the scale rich and ~10.5:1. Right now I'm at -50% across on the high table of the S-AFC...can't pull any more out...
I've tried repositioning the MAF, found and fixed all vac/boost leaks, reset ecu, amount of boost doesn't matter, switched back to stock MAF (worse)...
Theoretically the afc should have plenty of range to control the 550's with the V8 MAF, my afc values just don't make sense...any insight is definately appreciated.

Thanks,
Marshall

aliga

iTrader: (147)

it seems like your afc may not be wired correctly or is not functioning properly???


as a test, with the car running: if you add or remove fuel at idle, do you see a change in the wideband?

mamurra2

yup, should've mentioned that it was tuned fine previously on the stock injectors, problem has arisen since I installed the 550's the other day

Lex Luthor

Are the 550's the same impedance as the previous injectors?

mamurra2

yeah, within a couple tenths of an ohm

thanks

T51R

sorry to jack your thread marshal. but hey john.. long time no talk...
how are you doing... how is your car.. PM me or call me sometimes

mamurra2

I switched my maf from blow-through to suck-through and did some more pulls, it's a little better top end (~11.5:1) but it still does the full rich bog when i first go WOT prior to 4500rpm. If I floor it @ or after 45 then it's ok...

I guess it's worth mentioning that I pulled all but the necessary vacuum lines out while I had the intake manifold off. Pretty much all just emissions stuff = unnecessary. Pressure tested after for leaks, none.

Really don't want to downsize injectors, haha I'll run two afc's in series before I go down to 440's ;-)
Any other thoughts (besides tsukasa's) are appreciated.

T51R

run my 1000cc be done with it...
hey you spell my name right.. that is whats wrong with it

wmulli

Ya know, the V8 MAF only flows about 25% more air than the stock MAF. Since the stock injectors are 330cc's, the MAF should only be good for 440cc injectors (330 x 1.25% = 412cc). I think you need to consider a VPC, or even better, do without the MAF by going standalone and using a pressure sensor

rscott

try playing with what throttle percentage it switches between low and high tables. It might be that theyre either too far apart so that when youre between low and high, youre getting an average of the maps. That might be why at low rpm youre getting the bog. What are they set at now?

mamurra2

wmulli - i have an afc...50% either way...

rscott - they're at 20% and 75%, but my high and low table values are so similar that there isn't much interpolation between...I'll try tightening them up a bit, see what happens.

I pulled the claibration screw out of the MAF so it's letting more unmetered air in, it leaned it a bit more and it's now tuned decently above 4000 rpm, still have under 4000 wot full rich bog though, I'm learning how to drive around it...

for future searchers (recap)

Denso 550cc, S-AFC, V8 MAF (calibration screw completely out, pulling through - was richer when running blow-through)

Low table/High Table:
1000 -30% / -40%
2000 -40% / -45%
3000 -50% / -50%
3500 -50% / -50%
4000 -50% / -48%
4500 -50% / -47%
5500 -45% / -46%
6500 -40% / -45%

A/F average = 11.7:1 @ 10-13psi

Car is staring to feel pretty good now, auto tranny is hating life
Going to the track tonight, best time previously was 9.1 @ 80mph, really wouldn't mind hitting 85mph tonight.

Thanks for the replies. Marshall.