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rb25det tuning , link g4+ plug and play

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Hello , a friend of mine has a r33 gts-t with an rb26 bottom end and he asked me if "you could take a look because it does not idle"

and here are the maps that i came across:

the car has no IAT sensor

It does not read or correct lambda

runs on pump ethanol blend but has no sensor

everything was made by a professional who charged the previous owner over 1000€ and had a perfect knowledge of the car setup

it was mapped on a classic ( master pulse width ) mode and i think i should go with modeled fuel table if i want to go flexfuel later on.

the thing i am worried about is timing advance , since i will have to road tune it . Is there a way or known numbers for timing advance that will allow me to run the car safely and make all the fueling work ( including idle , cold start and so on ) i am not taking performance into account , just make it run on pump RON98.

car setup:

rb26dett bottom

rb25det head

1000cc bosch injectors

greddy plenum single tb

spitfire coils

greddy boost controler

forged pistons and rods ( waiting to know the compression ratio )

mambatec gtx3071r

i have attached the tuning file that was sent by the tuner after i asked him and i matches what was extracted from the ecu the first time my friend plugged his laptop


Attached Files

Hi Anthony,

I've had a quick look through that map and there's a bunch of issues that I see. First of all i'd say that a lambda input is nice to have and I'd always add one into an ECU where possible, but it's not essential. In the first 10-15 years of my career having onboard lambda was very rare. Of course you still need a wideband on the car when you're tuning it though. Next up let's cover E85 - pump ethanol varies dramatically depending on summer to winter and where you are in the world. From memory the minimum legal ethanol content for a winter blend can be as low as 56%. Simply put, if the ethanol content is varying that much you have no hope of getting a reliable tune without an ethanol content sensor and a proper flex fuel tune.

Looking at the existing fuel map in graphic form shows a complete mess with spikes and valleys all over the place. While I don't advocate that every map should be perfectly smooth, what you've got there is almost certainly not optimal. Likewise the timing falls off a cliff at 120 kpa, although the on boost timing is probably in the ball park at least. Lastly as far as the idle control goes, I'd at least start by setting up idle ignition control which is currently switched off. Basically i'd recommend starting from scratch and tuning the engine properly.

I can't tell you what timing you should be running as there are too many variables to consider sorry. I'd recommend getting yourself a Link G4+ knock block and using that to monitor for knock.

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