hi all! i´m still fighting with my 396 that i built, and im close to give up... specs: 396, AFR 195comp.port heads, XFI 467 cam, single plane EFI the car idles ok, have power @ WOT, but, driveability, especially down low is not very great. when i´m driving with light load ( e.g. 2000rpm), i have no steady purr i found some lean spot when holding the to 2000 rpm in neutral, i have a Map of about 36kpa there, 43°SA, no knock, but...WbO2 shows AFR 16:1, datamaster shows BLM 115, Int. 124 the sound of the exhaust is a purring, and some popping, would say, about 1 short pop every 2 seconds..and i think, thats the same condition i experience under light load driving, except, the MAP is about 50 there... at idle (850rpm, 55kpa Map) i run 26.7°SA, BLM are 133, Int 129, WbO2 shows AFR 13.5 :1, also the smell at idle is horrible....would cats help here? i get my ostrich to work, this will ease the tuning, i have had to short the cable for the ecm to about the half, and now it works fine....so, i can emulate in real time.. i´m a bit lost at the moment, seems, i cannot get this damn thing running right.... if anybody wants to take a look at my .bin files or logs, please let me know, would be more than happy to send them.! thank you

So have you tried less timing at that RPM? I know that I have tried over 38 degrees at 2000-24000 rpms 35-45 kpa (my cruise range) and my engine didn't like anymore timing. It seems to like about 37* as the engine pulls smooth and the exhaust tone sounds great. What I did was keep 1800-2200 at 37 and then bumped 2300-2400 to 40 in the bin. That way I could see the difference in TPS as well as listen to the exhaust tone and see how much my MAP changed on that tune. I started to get that popping with the higher timing so I figured that was too much timing. BTW I am not using highway mode yet. In the stickies there are a few posts that would help you. First check the one on tuning an engine with a cam and then check out the one about O2 constants. I have my O2 constants lowered and while the smell is not completely gone it is much better then the stock settings.

Hi 84KYSS

unfortunately, i didn´t have so much time yesterday, but, this will be my next thing, i will try out..maybe, our heads are so efficient, that they need less timing.

so, you did have the same popping, i described, with higher timing numbers?

i have now up to 45° @ 2200rpm, 50kpa (cruise), maybe thats too much timing..i will feed my ostrich next weekend with a .bin with less timing.

i also have highway mode disabled.

i have spent a lot of time here, reading the stickies again and again, i printed articles in the size of two phone books, i have tried real a lot, taken logs, aso..maybe i´m just in the wrong direction.

to the o2 constants at idle...i have lowered them to 460mv lower, 506mv upper, 53mV Hysteresis, 480mv Fast R/L threshold...
my opinion, the smell comes from overlap, i ordered two high flow cats yesterday, HTH

another question..what is with the O2 parameters, slow O2 R/L vs MAP (upper-lower) threshold..what does they affect?

unfortunately, i have to wait for the end of the week to try again...!

i will let you know, what i found out..

thank you