carls1982z

I read here once i think of turning dfco off until you get your blm in line.--as im getting surge on decell between about 1600 rpm down to 1000. - is this true, and how the heck do ya do it. -lol.---- im tuner pro and 7747 ecm.

RBob

iTrader: (1)

Easiest method of turning off DFCO is to max out the temperature enable threshold. If that isn't in the ECU/XDF file, set either the RPM or the MPG values to maximum (2 values each).

RBob.

Ronny

iTrader: (1)

could your VE tables be lean there? consider adding some fuel in those cells. if i recall i saw no CL correction below 30 map in my .bin. i set the threshold for BLM to 21 so that i saw corrections at 25.

carls1982z

yea maybe, ?? --- i had read here to turn dfco off in order to get lower rpm/map ve in line then turn back on ? - how true this is ???????

RBob

iTrader: (1)

Yes, should disable DFCO when working the VE tables in. Don't forget about EGR, CCP, and highway mode.

RBob.

carls1982z

ok, heres what i see in tuner pro with my 7747 ecm.---DFCO IAC DECAY COEF, -----DFCO UPPER MAP,THRES, AND LOWER MAP,--DFCO UPPER RPM THRES AND LOWER , ---DFCO MAP, THRES [O/L],--DFCO RPM THRES[O/L],-----------AND my egr is set at temp on, 0.00[thats where i was told to keep it] [i thought it would should be at highest setting ?]--------what is ccp, and highway mode.

RBob

iTrader: (1)

Try setting these two entries to 6375 RPM:

--DFCO UPPER RPM THRES AND LOWER

That should disable it.

CCP, charcoal cannister purge
highway mode in the 7747 adds timing

An EGR temperature enable hex value (actual BIN value) of 0 is maximum temperature (151C).

RBob.

carls1982z

THANKS THERE, RBOB

carls1982z

i found and turned off the dfco, but see and feel no diff, but i loged blm and werent bad.-- i richened the whole lower map/rpm area to see if it helped my off gas surge and will let u no.---car loves the richer fuel added ? blm were at 115 in wide aver in wnaldl.- compared to 123,- ill have to get off my lazy ..., and check with my wide ban, that i still havent used.---Do you think i should ignore what wnaldl says and aim for 115 untill i check it with wide ban ??------refresh me here to, - if say my blm is 120, and int says 127, is this saying its just trying to get it closer to 128 ?? and int is just a short term adj.

RBob

iTrader: (1)

There are a number of items that cause surge on decel.

Proportional gains too high
ECM switching in & out of async fueling mode
VE tables too small for engine combination

Without decent data logging best you can do is to eliminate each and see if it does the trick. Lower the prop gains at low airflows and see if that helps. IIRC the '7747 has a method of doing an open loop decel mode. If you can figure out how to do that, it completely eliminates prop gains during decel.

ECM using async fueling mode: set the high/low transition points to 0 msec. That will eliminate the ECM going into async fueling mode.

VE tables too small. If the engine is cammed this can be an issue. There just isn't enough granularity in the VE tables for engine that don't have an even, smooth VE over load & speed.

RBob.

carls1982z

heres what i see in tuner pro with 7747 ecm on the async.---min asych, bpw[null[0.00]and [null]686.25,----- max async bpw,[null]45.75, and[ null]274.50. is this what im suppose to put all to 0 ?? ---and the other i see is, async fuel multi, vs rpm.

RBob

iTrader: (1)

Don't believe it is any of those. Try these:

Minimum BPW Hyst Value
Minimum BPW

They will be at addresses $2D6 & $2D8

The names above came from one of the more popular ECU files for the '7747.

RBob.

carls1982z

rob, heres what i see with my 7747 ecm and tunerpro.--- close as i can find what you stated is. [2D5] CHOKE COOLANT HOT/COLD, -- AND --[02DE] MIN ASYNC BPW. AND it has two null readings,[0.00] and [686.25]----------when you say the ones you posted came from the more popular files, you mean ?? xdf ??---THANKS

carls1982z

ROB, DID YA SEE LAST POST OF WHAT I FOUND

carls1982z

Refesher of what i got as im out of ideas.---Veh has off gas surge [no load] from approx 2000, rpm and down,--also when it goes closed loop at idle [in park] its erattic and is unsteady [up -down] about 300, rpm.[seems to be at no load ??]-------Now wnaldl shows my BLM OF 122 in gear at idle, and big drop to 115, as im into gear.----Now i hook up my wide ban [ZEITRONIC ZT-2], FOR THE FIRST TIME AND see, that in gear my afr is from 14.7 too 15.5, and is up and down very fast.--AND in park, its from 14.7 too 17.00, and up and down very fast.------Kind of lost of what to change or check, and any help would be very great guys.---Seems to me that something in my bin when it goes closed loop is telling it to go to lean, ??????---AND if its important when veh is cold [below 120c] veh is way to rich.

RBob

iTrader: (1)

It isn't any of those. The ones I listed are from the 747-mine.ecu file. Most likely there is a copy of it as an XDF. Otherwise just import it.

RBob.

carls1982z

I HAVE THAT 7747 DOWNLOADED IN MY DOCUMENTS,[ GOT IT FROM TUNERPRO SIGHT.----BEEN USING A 7747 XDF,DEF FILE ??- I HAD SENT O ME.-----IMPORT IT ????:"? [NOT GOOD WITH PC]--YOU MEAN I JUST OPEN IT,? -- I DID THAT THEN IT SAYS THERE IS NO XDF AT UPPER CORNER OF TUNER PRO.-----COULD U EXPLAIN BETTER FOR US [ME] IDIOTS

carls1982z

Hey, rbob. i figured it out and i got thos two address now--- So when i open to edit them ,they both have [TWO] null settings -each one has a 0.00 at one and also readings in the other[null] are these the high and low tran points you mentioned, ?? and i just chang the ones with a readingS below to zero., ??--sorry for all the questions but just want to get it right.-------I owe you a million thanks.

RBob

iTrader: (1)

Sounds like that definition file is F00 bar. If each term has two values with it, make them both 0.

The typical stock settings are around 790 usec and 500 usec.

RBob.

carls1982z

THANKS, Ill adjust both null settings to zero in each, and check it out and let you know.---Is this something i deff need to leave at zero, or only if it fixes.

carls1982z

ok, heres where i am.---DFCO IS SET at max rpm[both]----I lower my min BPW HYST VALUE [$ 2D6] TP O.OO, and my min bpw to o.oo.----NOW i lower my proport, gains to how much, ????? --- is mutipling both of them by say, ? 0.85, to much. ???

RBob

iTrader: (1)

Actually, for now leave the prop gains alone. You have made two major changes to the calibration, try it out and see how it is. Take notes, go slow (Grumpy).

The reason is that one can make too many changes at once and not know what did what. Better to drive on what you have, take notes, and drive it some more. Then make another change and see how that is.

RBob.

carls1982z

yea, i put the prop gains back where they were,[stock asdz bin] ---And logging and adj my blm with DFCO OFF.----And yes i was changing to much, and i should no that by now.--Also i had richened the hell out off the ve table, and saw no affect in the off gas surge.,[ except for gas gauge drop] -- so im adjusting BLM all over again and ill let ya no how i make out.-------ONE thing is odd, is when i had it richened 108 blm [wnaldl] it had hardly any back firing or popping out exaust, and as i get my BLM closer the major popping back fire starts.---Maybe im chasing a ignition problem ??????

carls1982z

UPDATE. Heres where i am.---put in new distributor, coil/cap and plugs,-------Set -DFCO OFF AND set dfco hyst to 0.00,---done alot of logs, and cant get rid of off gas surge.-ill be off gas at say 37 mph, and it nose dives down [rpm][350 rpm] and back up then down again.--also, very hard time getting lower blm in line, 800/1200 and low map. Was too rich, as when it was cold it was too rich and would dump fuel on accell, at temp below 130.------I played with ve table best of what i no, and now is still very eratic idle and rough, untill its at least 135 degrees temp.--Seems to be fueling isnt quite right under a NO LOAD, situation.-not sure where to go now.-- HELP !!!

carls1982z

Any suggestion guys on my last post ??

carls1982z

Hate to say it, but this tuning stuff is getting me very ????, about ready to put in stock ecm and high fuel pressure and call it a day.-----Ive gotten no where in all i was told, to do for my off gas surge, and idle flare,, up and down. ---WNALDL says im good in my blm readings [close to 124, wide aver]-and in park it says im rich at 115, BUT - --I just hooked up wide ban again and it says im any where from 14.7 to 19.5 afr in park at idle [idle up/down]-???????------Is 7747 ecm, and wnaldl just to slow to show this or what, ???? recently changed plugs and they show deff way to lean.-------Im lost as to what to check any more or adjust-------ANY HELP would be great as im out of ideas.---tuning has went from fun to a head ach.

carls1982z

Help , -anyone.

Cflick

Reading the whole thread, I gota ask....
Have you checked your O2 sensor ?
If it says rich, and the wideband says lean, something ain't right.
If it's already lean, and the narrow band is leaning it more, I'd expect the problems you're seeing.

Ronny

iTrader: (1)

do you have a heated NB DELCO sensor? I think you have headers right?

I did not have much of an issue with non heated with my long tube ceramic but i did see evidnece of it falling out of CL under light load 2000 rpms. the heated gave me more stable A/F on WB all the way around.

I assume you flattened the SA in those areas you see the issues.

also is the IAC in your logs changing up down with surge. today i have my iac passage plugged and IAC disconnected as I cannot get the wiring down as far as my crossfire harness to GM 7.4L TB. I tried all recommendations given. that disconnect has caused a very steady idle WO the IAC. maybe a temp solution is to unplug IAC and plug passageway to determine if IAC action affects/hinders your drivability.

carls1982z

I did have a heated 02, before i put the wide ban in its place. [at 3" past collector] Then i put wide ban there, and moved narrow band 02 to left header.[eldebrock]-- seems to be staying in closed loop also, after it switches there,.---And on IAC MOTORS they seem to be ok, and at idle when its going from 14.7 to 19.0 AFR, they are at 0 steps.---And on that narrow band 02 reading i see at idle that wnaldl, says its, any where from 0.155 too 0.928, [aprox].and switching. And it hits in between thos #s once in awhile. Kind of lost as to what to try and see , and change to get rid of lean condition. -I even went as far as raising my pulse width, but all it did was made BLM at a richer #s,