carls1982z

been tuning on and off since april with my 82 crossfire and 7747 ecm with tuner pro.-------ever since the start ive had a surge as use decell and off the gas, an d goes away as soon as there is slight amount of gas.------was told too look at my [dcfco] ???? i see a few listings and need more info, [dont like changing things unless more info]------lower #s or raise ??? any help would be great.-------also if i may, when determining when to have say PE INABLE % TPS, COME IN, is this more of user preference and veh perf,

Grumpy

Yes, that can be a PITA.
I probably have more time in that area, then anything else in my tune. It wound up being a combination of things. VE table, min PW, and then just tinkering with the Deccleration enleanment, and DFCO. My best advise is gong slow, making small changes, and taking notes.

carls1982z

thanks grumpy.--so do you know if theres any articles out there on [DFCO], I HAVENT SEEN ANY.

Dominic Sorresso

I have been struggling with that area for quite some time. Bottom line for me was a PW that was just too small. My setup is using 80# injectors with 20psi.
At Decel the PW would get into the .8-.9msec range. With EBL I have been able to implement using the Vacuum Port on my Aeromotive 13301. This way at low gms/sec airflow, the PW remains reasonable. No more stumble. Not sure if this is your issue, but that's my experience.

RednGold86Z

iTrader: (1)

At what RPM and MAP are you having the surge, Carls1982z? You say it's closed throttle, as in completely closed, right? You should set up your DFCO settings to ensure fuel is cutoff the whole time (just raise the MAP settings equal amounts until it stays in DFCO down until the lower RPM threshold). No fuel should equal no surge, until you start to get to very low RPMs, near idle, then it's the usual wrestling match of fuel, air, and spark, and vehicle masses.

carls1982z

thanks everyone, i havent paid too much atten too exact rpm or map when surge is there, but crusin lets say in traffic with VERY SLIGHT GAS, the surge is not there. then let off completly on gas it starts. feather gas again and its gone.--------say red,- increase map? do you mean my delta map acell ??????---------------And dominic, my set up is 20 psi fuel and stock 82 injectors,--and bpw set too 100,-----raise it ????----------------update i forgot too mention that i always had and still have a surge at no load[lets say park] and when you rev up in park too say 1800 rpm it surges up/down about 300rpm, ive played around with the ve table but doesnt seem to help ?????-------and it has no vacumm leak.

RednGold86Z

iTrader: (1)

I mean the MAP value for entering and exiting DFCO (Decel fuel cutoff). If the throttle is closed, and the RPMs are up above 1500, then you should be in cutoff, and no fuel would be injected, thus no surge possible. Without a log of what you're describing, that's my best guess.

Ronny

iTrader: (1)

i believe my DFCO is disabled as i am dialing in my VE.

would disable be a better idea until you have all else OPTIMIZED ??

ps. when i ran the xram i was of believe the DFCO wiped my wetting surfaces of manifold dry. so i disabled. there is a lot of surface in XRAM and possibly CF as well.
seemed my WB02 reflected that A/F as lean and only AE would get A/F back to a reasonable amount after prolonged DFCO. i think i disabled DE as well but is functional now in my bin. i could be dead wrong on that.

carls1982z

thanks red, i found and adjusted thos map readings at dfco and raised them slightly, been driving today and seems ok,?? but before it had gone away then had come back, but ill let ya all know.-----i also forgot too mention at no load, reving up in gear and trying too hold a certtain rpm it would nose dive up/down about 300 rpm, seem to be at 30 map so i leveled out the table. alot better but still some ???? ill let yha know

carls1982z

up date, surge still there on and off ????-----drove veh trying too see what condi, make it come and go.---crusin at say around 45 mph and 20000 rpm and you let off gas completly, there is no surge at all, BUT, IF you are say 17000 rpm and crusin and decell it starts surging ? [maybe why i noticed in city driving]----also its about a 300 rpm surge up and down---same as the surge i get with no load lets say in park and you rev too 2000 rpm.--------------LOW MAP 20 NEEDS RICHEN ????? -------ANYONE here want to look at my bin ??

RednGold86Z

iTrader: (1)

Do you have a log file of the problem? That would help just as much as the bin. You can attach files on here, so that anyone can look at them, .zip them.

carls1982z

red, when you say log--do you me a log of my BLM ?????------------------as for the ZIP im new too the pc so ??????????

RednGold86Z

iTrader: (1)

hmm, I mean a logfile, like where you connect your laptop, record the ALDL data during the problem using tunerpro or whatever.

Not sure how to explain zip. Download winzip from download.com, and install it, and read the instructions i guess.