Delco tuning for for dummys

[Holden202T]

why not just use scanner pro with the interface you have now then play back the logs and change you tune then upload with flashtool with the interface you have ?

then you can also put the wideband into the aldl stream

[Dec_head]

I was disonnecting scannerpro and reconnecting after changes etc but forgot all about datalogging but at the moment it can wait until it is all working properly it is idling ok now but i have to register it before i can go any further out on the rd and it needs some money thrown at it wich i don't have at the moment .

[Dec_head]

How should i calculate the target afr lets say for instance it runs smoother on the rich side at idle in open loop can i just change the target afr to 14 or 13 even until it stays in closed loop and idles the same .

[Jayme]

in dont really understand what you are getting at, but its never going to enter closed loop unless your target AFR is 14.7 anything else and it jumps to open loop. as far as how to richen it up, the idea is usually to increase VE until the real AFR from the wideband matches the target AFR. once its matched, then you can just adjust the target AFR to whatever fuel ratio you want to run.
most engines love to idle at a bit richer than 14.7, usually somewhere in the 13's, if you go closed loop 14.7 at idle youll probably find the engine revs/misfire in time with the rich/lean loop.

[Holden202T]

from my experience from my mates 304 is likes to idle about 13.5-13.3 .... but its a matter of what each engine likes really.

my mates also surges if the AFR is 14.7 below about 2000rpm so i changed it to be about 14 in those areas so it wouldn't go into closed loop.

[Dec_head]

ok so from what your saying jayme is that closed loop target is 14.7 and can't be changed ?
I thought i could change the target afr to keep it in closed loop but with a target afr of say 13.5 for example where it would be happy.

[delcowizzid]

it shouldnt closed loop idle for long anyway set the timeout for it less may help then it will goto open loop idle sooner cant remember exact figures but it should be like 10 second delay before going open loop at idle can set it lower then it will run off the idle fuel ratio table thats set at 13.4ish :1 ratio

[Jayme]

there is a constant in the tune for Stioch AFR which tells the ecu what AFR to enter closed loop at, it is set at 14.7 from factory obviously but it must match the swing point of your oxygen sensor. as all narrowband oxygen sensors swing at 14.7, you cannot change it. if you were to change it to 13.5 anyway, it would enter closed loop at 13.5 target afr and keep leaning out till the narrowband hit its swing point, which means you will end up back at 14.7 anyway......

short answer .. no closed loop is 14.7 and you cant change it.


if you were to however, hook up a wideband and program the narrowband simulated output to swing at 13.5, then you change the stoich AFR to 13.5 to match, then you will have your 13.5 closed loop, but it would be a guzzle ron the highway coz you will be stuck at 13.5 unless you went open loop for cruise areas. either way, bad idea, you are better off stickin with a stock oxy sensor

[delcowizzid]

i think there is a switch voltage as well that can make it swing at different voltage the hsv v6 tunes have it set to swing at 350mv instead of 450mv sort of lean cruise to make up for the extra fuel elsewhere to keep it reasonable on gas.but that isnt needing changed at all to fix your issues

[Dec_head]

Ah ok i think i understand now thanks might just try what delco mentioned about the time delay
And the stoich as well i'll have a play .
When it enters Closed loop it seems to lean it out a bit and it doesn't like it.