Piggy Back vs. Standalone

[SkylinesSuck]

So I'm heading back to the states from japan (Air Force) in six months and my '98 TJ with a Golen stroker is waiting for me. It's got the gambit of bolt ons, but the only thing on there right now for tuning is a MAP adjuster. I want to spend a little time getting the tune a bit closer to where it should be. Right now it starts out with 14:1 a/f's below 2 grand and down to 11's by red line, and that the best I can get it last time I was home on leave (I've got a wideband). I'm trying to decide right now between an Apexi SAFC style piggy back or something more like a unichip or even megasquirt. I know the SAFC won't touch timing. Is that where most of the gain is found, or would getting the fuel close get me 80% of the way there? Are there any complications to using a SAFC kinda deal with OBDII? I've heard people say the factory ECU tries to learn it's way around the SAFC settings. I've searched around some of the thread, but have only found a couple with results or even butt dyno impressions after different tuning techniques were applied.

I'd like to do more with it in the future, but for right now, I don't want to juggle to many projects. I'm taking my other straight 6 (RB25 in my skyline) home with me to put into a 240sx. No I'm not a ricer/import guy, but I'm in japan, so what do you want? I'm making somewhere in the neighborhood of 600hp with a Holset HX40 turbo on it now, so it's going to fullfill my go fast needs right in the near future, not the jeep. Still, if I can spend a little time and money on the jeep now while I'm putting other things together and get a substantial gain, I will.

[SilverXJ]

I've heard the same thing about OBD II and a piggy back and it just isn't true. I've been running the SAFC II for quite a few years and it never unlearned the settings. Unless you don't want to get it inspected and want to redo your gauges, I would go with the Unichip, PSC1 or SAFC over a Megasquirt. Personally, I would choose the PSC1 as you can tune it yourself. The SAFC works fine for me, but the PSC1 has more points to tune and isn't that much more expensive over the SAFC. Regardless of which you choose, the computer will still be trying to achieve 14.7" AFR in closed loop. These devices only change open loop.

[eliv1]

I would also consider the painless system, it sound's very cool and its fully programmable, the only downside is the $$$$!

[amcinstaller]

someone here used the painless system. there was a bit of a "to do" about the programming, and another piece was needed. ill see if i can find the thread about it.

[oletshot]

It was heartlandoffroad using the painless system. IIRC it was a serial adapter causing problems.

[dwg86]

I have been trying to get my head around all of the different controllers and how they work. This will be my first time trying to tune a computer controlled fuel injection (still an old carb guy). So from what I've been reading...the safc II does not use a laptop. You tune using the screen. The psc1 needs a laptop(no screen). Also the safc II will show the air/fuel ratio and the psc1 will need an air/fuel gage. The psc1 is cheaper than the safc II, but need to buy an air/fuel gage using the psc1. So the cost will be about the same?

The unichip is preprogrammed or will need to be programed at a shop the is set up to program them.

Is this correct?

[SkylinesSuck]

SAFC doesn't display or read 02 settings. You need a wideband for it also, but you do tune it through the it's own screen. I've never used a PSC1, but you can find used SAFC's for like $100-$200 on ebay.

SilvrXJ, what were you impressions of gains from the SAFC tune?

[SilverXJ]

dwg86, I know of no piggy back that comes with a wideband built in.

I never actually got to point on the previous stroker when I could get it on a dyno and check for gains or mess with the map to see if i could uncover some more power before i ripped that pike out. I do know what it puts the AFRs where it in a safe zone. Maybe on the engine I am building now I will be able to.