stenot2low

My car has a 2jzgte swap ,single, stock cams , 550 cc injectors. 2 fuel pumps fuel pressure at 38 psi at idle. My safc2 is set at +30% at idle to make it run decent. I was wondering if this is normal or should it be closer to 0 at idle. Ay help is greatly appreciated . I searched but couldn't find any setting info.

rexst

I was of the understanding that the 2jzgte came stock with 550cc injectors and if this is the case, why would you need to enrichen your fuel at idle? Shouldn't the stock ECU be just fine at controlling this? This is a sincere question because I'd have thought that the ECU would handle this perfectly.

lexforlife

iTrader: (7)

if it is a aristo 2jzgte swap then inj are 440

stenot2low

That's why I was thinking this is wrong and I have a sensor issue or a bad ecu. Just curious if other people are near this or totally opposite ,taking away fuel at idle.

Ali SC3

iTrader: (10)

something is wrong, you should be pulling fuel away at idle with a jdm ecu or 0 with US ecu.
do you have a wideband and are you sure you need to be adding fuel?
have you reset the ecu and seen how those safc settings work on a fresh re-learn?
reason is if you are just sitting there adding in fuel at idle with the safc in closed loop, the stock ecu will try and counteract by removing fuel if you are above stoich. so you get a big plus number on the safc which is being counteracted by the stock ecu, and it gets you no where and is not very good way to tune.

I would zero everything out on the safc, reset the ecu, let the car warm up and see where it is without any correction. If it is not running right then your problem is not with the afc settings, and you should track it down and correct it before messing with the afc.

stockhatch

iTrader: (12)

I thought SAFCs modified based on "airflow" and that + means more air (leaner) and - means less air (richer)? Or do I have this totally bass ackwards? If I have it correct, then wouldn't his adjustment be about right for an Aristo on 550s?

Luv2xl

iTrader: (5)

Stockhatch; the SAFC adjusts injector pulses..

and your explanation is spot on however, based on air corrections..

Luv2xl

iTrader: (5)

agreed... you shouldn't have to adjust closed loop (idle) just open loop..

stockhatch

iTrader: (12)

I am pretty sure it adjusts map signal and tricks the ecu into adding or subtracting fuel by making it think there is more or less air entering the engine. At any rate, I had it backwards, the adjustments do correlate with fuel directly. That means +30 is actually adding 30% fuel after all.

If resetting it to 0 does not improve the way the car runs, i would totally remove the SAFC and see how it runs without it.

Also, check your settings to make sure it is correctly set to map or maf based depending on if you are JDM or USDM.

Ali SC3

iTrader: (10)

yes it modifies the map or maf signal depending on what ecu you are using. only the better ecu's like the aem fic and maybe the emanage ultimate can modify injector pulses.

It doesnt just add or subtract fuel its also adding or subtracting timing (its really adding and subtracting load if you think about it). I don't like to idle at 20 degrees timing, im not sure how you are idling well at +30% it must be because of the lower compression. you are prob knocking but the ecu will learn to pull out the extra timing.

The stock JDM ecu can learn to run 550's if you give it enough time, and will provide extra fueling at WOT (open loop). the only reason you would install an afc is to remove fuel in your case, but it is not necessary. and you don't need to physically remove the safc, if you zero out all the high and low maps, it will not modify the map signal at all. zero it all out, reset the ecu and diagnose from there. be sure to write down your old tune.

stockhatch

iTrader: (12)

I just suggested removing it if zeroing did not fix the idle issue. I have seen bad or improperly configured piggybacks REALLY hose up a car. Removing it completely is a last resort that will tell you for sure where your problem lies.

Luv2xl

iTrader: (5)

Changes in air-fuel ratio are achieved by correcting the airflow sensor signal or pressure sensor signal at 16 different RPM points, and at high and low throttle positions, all of which can be moved according to the customers needs. By changing this input signal, the tuner can alter the injector pulse width as calculated by the ECU.

from the Apexi site..

stockhatch

iTrader: (12)

All the SAFC does is modify map/maf signal. The ecu trims or adds fuel based on the bogus reading that the SAFC provides it.

I have seen thread after thread on multiple forums related to SAFC or similar units wreaking havoc on their cars. In many cases, physically removing the unit is the only way to get their car running again. Not that this is the case here, but if the car wont run right no matter how you tweak the SAFC, I would not start replacing sensors or ecus until the SAFC has been removed from the equation.

Ali SC3

iTrader: (10)

They should say "Indirectly" alter the injector pulse. yes, the injector signal gets modified, but it is done by the ecu in response to the load the safc reports. more load increases fuel and timing, less load reduces fuel and timing. Remember this is really a false load being reported to the ecu, it is far from ideal to lie to your ecu and often results in poor driveability.

If it modified injector pulsewidths directly like the FIC, there would be no alteration of the map signal at all, which means you can change fuel while keeping the correct timing values, which means you can use much larger injectors with an FIC than an safc, which performs erratically over 50% correction in most cases.

I can attest to that i have come across a few cases of improperly wired safc's wreaking havoc. people get the ground wrong or just plain wire it incorrectly, or a wire comes loose. not the worst idea to just take it out, but you will have to rejoin your map signal wire you previously cut in half to install it.

Luv2xl

iTrader: (5)

^ gotcha.. Learn something new everyday.. Appreciate the info. And now that I think about it, those are the wires used to tap into which it all makes sense.. JHC..