NA/FI tunning info with stock ecms
11-12-2006, 06:23 PM
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NA/FI tunning info with stock ecms
WELL i had some time over the weekend to experiment with injectors and fp on a bone stock 89 firebird today.this car is getting a turbo system so i made a few mods to the fuel system and id like to share some info on what ive learned.
on this particular car we installed 24# injectors and a afpr.in order to prepare for the turbo install.
well the misconception that installing larger injectors and the car will not run right without a custom chip is not true.now if this will work on a speed density system i dont know yet.
with 24# injectors and 50#'s base fp the car will cruise around with a 14.5 - 15.3-1 afr.wot test showed an afr of 12.0-1.
on decel with the larger injectors it was a lil off instead of the usual afr of 18.5-1+ we were only seeing 16.5-17.5-1.and on sudden throttle lifts we would dip down into the 10.0-1 range but quickly rising back upto the 16.5+range
these injectors are big enough for the badest na 2.8/3.2 u could throw at them.and big enough for around 325hp turbocharged without an fmu.and around 400 with an fmu and supporting fuel pump
though anything over 9 psi of boost the stock fuel pump cannot keep up with the fuel demand
in short if ur planing on doing cam/headers/port work larger injectors upto 24# will run correctly in the car,as far as something larger u prolly will run rich.
24# seems to be the limit at which the stock ecm can lean out the motor to the proper afr.
i did some real time dataloging with my lm-1 that i will post after i label parts of the graph log so u can understand what the car is doing at each point i.e wot/cruise/light aceel/and decel
----------
as far as using the stock maf ecm on a turbo app
the ecm is limited to reading 255grams per second,which is around 7 psi of boost depending on what turbo u use.even computer tuning cant get over this obstical,the only ways around this is to change ecms,or install a piggy back ems,or tune with an fmu
ill add more to this in a bit diner is done lol
on this particular car we installed 24# injectors and a afpr.in order to prepare for the turbo install.
well the misconception that installing larger injectors and the car will not run right without a custom chip is not true.now if this will work on a speed density system i dont know yet.
with 24# injectors and 50#'s base fp the car will cruise around with a 14.5 - 15.3-1 afr.wot test showed an afr of 12.0-1.
on decel with the larger injectors it was a lil off instead of the usual afr of 18.5-1+ we were only seeing 16.5-17.5-1.and on sudden throttle lifts we would dip down into the 10.0-1 range but quickly rising back upto the 16.5+range
these injectors are big enough for the badest na 2.8/3.2 u could throw at them.and big enough for around 325hp turbocharged without an fmu.and around 400 with an fmu and supporting fuel pump
though anything over 9 psi of boost the stock fuel pump cannot keep up with the fuel demand
in short if ur planing on doing cam/headers/port work larger injectors upto 24# will run correctly in the car,as far as something larger u prolly will run rich.
24# seems to be the limit at which the stock ecm can lean out the motor to the proper afr.
i did some real time dataloging with my lm-1 that i will post after i label parts of the graph log so u can understand what the car is doing at each point i.e wot/cruise/light aceel/and decel
----------
as far as using the stock maf ecm on a turbo app
the ecm is limited to reading 255grams per second,which is around 7 psi of boost depending on what turbo u use.even computer tuning cant get over this obstical,the only ways around this is to change ecms,or install a piggy back ems,or tune with an fmu
ill add more to this in a bit diner is done lol
Last edited by daves12secV6; 11-12-2006 at 06:28 PM. Reason: Automerged Doublepost
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