Im running a "moderately" ported S4 NA motor, and my ECU wouldnt push the stock 460cc injectors past 65% duty cycle, even w/ my SAFC2. I had issues w/ the relatively low duty cycle of the S4 PCM, even though im running a Walbro 255 pump wired direct to battery voltage, where at 7000rpm my injector duty cycle would seem to "max out" (w/ factory PCM) and my A/F's would rise to over 14.5:1 by 8k. so, I bought and installed some low mileage Lancer EVO9 560cc injectors (all 4) to fatten up the mixture. As expected, I no longer have issues w/ maintaining a good 13.5-13.2:1-ish A/F up to 8k RPM, but now, I need to run a -15-25% correction via SAFC to not run retardedly rich in the lower RPM's. My problem is this, I can tell what effects the SAFC has on messing with VAF input signals w/ timing and idle, especially at such large correction ratios, and im wondering if I can just switch PCM and sensors over to a S4 T2 setup so it would already be mapped for low RPM/high injector flow set up and need less correction, but what about higher RPM? can the S4 turbo PCM make decent power at higher RPM w/ out making/ seeing boost? is it mapped for such scenarios? is ignition timing workable w/ an RTEK for example for an NA application?




I know this is a lot of, what seems to be, nonsense or rambling to most, but i need to make a decision for a new engine management to optimize my setup asides from the f'd w/ S4 NA PCM, (obviously shy of full standalone)

 

PCM would = TPS in this situation... Correct?

If so, the S4 N/A TPS and S4 TII TPS are exactly the same.

I'm not completely sure what you should do in your situation, as I've never used a SAFC... And probably never will. BUT I do have a slight bit of advice... Get an aftermarket fuel pressure regulator.

 

my situation is pretty simple. in a nut shell, my engine is able to flow a good amount more air than a stock NA engine, and therefore the PCM is not really able to keep up. I know the TPS for S4's are the same, turbo or not, hence the VAF/PCM combo(factory mapping) become more significant. For low RPM/load situations Im finding the S4 NA PCM/VAF combo to require large amounts of correction to bring the A/F's back into "normal" w/ my new injectors, thus negatively affecting my idle/return to idle. I know (obviously) that the turbo PCM/VAF combo is mapped/tuned for ~550cc injectors and in turn is able to idle just fine, but im more interested in the S4 T2 PCM timing map off boost (or being run NA) through the RPM.\

My fuel pressure (w/ all S4 fuel rail/regulator) maintains a solid 40-42 PSI at idle and WOT @ 7-8k RPM to my surprise, the only real fluctuation happens at/below idle when RPM's drop enough to make the alternator lose voltage, therefore lowering rail pressure from a weakened pump



Im very limited on funds these days, and Im trying to find what management would work best for me (full S4 engine/manifold assy, moderately ported, open aux ports, 560cc injectors (x4) very free flowbexhaust) for the cost.

the options for me are (in order of cost)
1. S4 N326 PCM w. heavily overall (20-30%) correction, thus affecting ignition timing
2. S4 N318 PCM/Sensor setup on an NA (w/ unknown ignition timing map for high RPM/off bost)
3. S4 NA/T2 RTEK 2.0/2.1 w/ full control over timing and high control over fuel
4. Haltech E6K full standalone, "Do what you want" PCM

 

ECU would have been my next guess.

Anyway, if you EVER decide to upgrade (turbo, extreme porting, ITB's, whatever...) an aftermarket EMS would be ideal. There's a guy in the NW For Sale section that is selling a Haltech Sprint RE for $600.

 

i was considering that too...what got me thinking was, first off, the issues ive encountered w/ such heavy SAFC corrections on stock PCM's , and secondly the recent prices of full standalone computers (ive found a haltech E6K for $500 shipped, or N318 RETK 2.0's for $300

 

personally, i would run the rtek 1.8 with 4x 720cc, but thats only for a turbo ecu, so you would need the afm and pressure sensor also.

or you could just get an s4 N/a rtek 2.0, cheap and plug and play for your current setup. Rtek7 ECU Upgrade Detailed Information

ditch the safc. the 2.0 would do anything an n/a can dish out.

 

thats what i am leaning towards too... so far, from what ive been able to find, NO ONE has a S4 NA RTEK 2.0/2.1 used for sale, and new run $450 + cost of a PalmOS device VS. a Haltech E6K im watching currently goin for about the same cost... maybe full standalone might be the best choice... plus i can dump my VAF altogether...