Quote:
Originally Posted by serialk11r
You can use conservative "canned" tunes that will slightly lean out the highest load cells, which is extremely helpful to fuel economy for aggressive drivers because the factory tune is usually way too rich.
Leaning out the low load cells is done pretty frequently to save gas while cruising, and on less efficiently geared cars like mine you can definitely get 10% back just from the reduced pumping loss on the freeway. My engine runs at 30% indicated load on the freeway! The torque calculations work out to the engine putting out something like 13% of its available torque, and so it's gotta be running at like 400+ g/kWh BSFC. Highway cruising my car only does like 37mpg, when it has similar drag and RR to a Prius. Most economy cars are doing a bit better but any passenger car with a V6 or V8 is probably doing even worse.
Personally, a tune/piggyback would be one of the first purchases for me on my next car, because it both saves fuel and gets you more power (for relatively cheap compared to an exhaust or something too!), plus you get to fiddle with stuff like cam timing (the cam timing on some cars is set for more "response" and less efficiency).
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So, I think the piggyback would be especially useful after getting my header, but it's rare and no ebay seller has returned my message about shipping yet. I'll get it eventually, but the piggybacks are available any time of the day. I'm really interested in getting one, potentially.. tomorrow or the day after. Looks like you have to splice into the car directly in a lot of cases -- I'm dedicated enough that I'm willing to go that far, but I have a plan. Since all I'm doing is intercepting wires that go INTO the ECU, I think I could just as easily buy a 2nd ECU and do the modifications to it directly. Basically, on the inside of the little pin connector there is
a 90 degree elbow of metal, seemingly pretty thick, that I could probably cut and then run a small wire from each side to a hole in the side of the ECU's case. This way I could just unplug the modded ECU and put the stock one back at any time. My specific method of doing so I will put in a more devoted thread somewhere, but I would probably want to go the extra mile in spending the $50-60 on a spare ECU to save cutting any wires on the truck. I've installed mod chips on the tiniest circuits inside game consoles so soldering here will be no problem.
But I need your opinion of something. Alright, so, some people say I should get the wideband o2 and whatnot. Is this to basically know EXACTLY my air/fuel ratio at any given time? For like, really tuning it exactly the way I want? But what if I install the most optimum settings on the piggyback, the whole wideband setup isn't really necessary anymore, is it? Cool to play around with, but.. all I need are the right settings, if I am understanding this correctly.
So, roadracemotorsports.com has many products including some very specific SX4 tuning equipment, and since the SX4 also has the same J20A engine as me, I assume things will bolt on. I am not going to buy anything they carry except their piggyback, they keep recommending me to buy the overdrive pulley but I don't like the pulley's disadvantages. Reading online, 100% of people who have installed their piggyback is looking at a ~3 MPG gain on the highway, no complaints, no ECU re-learning, just a performance boost all around. They claim to have sat there tuning it with over 10 hours of dyno time and have perfected the J20A's A/F ratio map. It could probably be pushed a little further in either the economy or performance direction, but whatever software they have come up with is probably the best all-arounder. So I could probably just use their piggyback and not install the wideband o2 (or at least, not initially). I asked them and they said yes, their software will work great on the Vitara's J20A: "
Basically the pulley system and the piggyback ECU will work there. It does make a good difference in power and even economy. WIring it in is easy. It is just a matter of knowing the pinouts on your car. WE will give you instructions for SX4 and you adapt from there."
So, pretty much guaranteed that it WILL work, and the tune should be pretty much bang on being the same engine, but I can get the part itself elsewhere for over $150 less. On the website the picture is photoshopped to not show the logo (??) and it looks like they just put a sticker on it. I could just save the $150 and buy the actual part they send me, but tuning it myself might lead me to buy a $200 wideband o2 sensor, and probably would never get a map close to theirs, dyno time would probably cost more than the whole piggyback. If theirs is perfect, the software is worth the cost difference. What would you do? Can I extract a copy of their software from the unit and then later make small adjustments to it? If so, I think it would be wise to have their software as a base-line. Unless I can just obtain a copy of a good AF map. Then there isn't much point in spending the $150 extra on theirs?