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As I've been learning more about cars, I keep hearing about how manufacturers are conservative with ECU settings.

For someone who isn't into racing, but would like a bit better performance out of his daily-driver, what's the cost of reprogramming the ECU to do things like improve the air/fuel mixture, and/or adjusting the timing to accommodate premium fuel?

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  • I'd like to know about my 2006 Pontiac G6 specifically, but in the interest of StackExchange, general answers are better.
    – Matt
    Jan 13 '16 at 15:33
  • Which motor do you have in it? Jan 13 '16 at 16:59
  • Note that another more nefarious (or off road) reason to reprogram an ECU is to delete emissions devices. I remember looking into some chips for my '99 Jetta, and as a "bonus", they would also allow you to delete the secondary air injection system, which was a common, expensive point of failure. These were sold "for track use only"...
    – JPhi1618
    Jan 13 '16 at 19:00
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    The underlying point is that an ECU upgrade might accidentally be an illegal upgrade if you don't research it. Selling a car with a modified emissions device is against the law.
    – JPhi1618
    Jan 13 '16 at 19:06
  • The benefits of an ECU tune/reprogramming will vary greatly from car to car. So this is tough to answer definitively as a general question.
    – Ellesedil
    Jan 14 '16 at 22:48
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You can't necessarily re-program an ECU that is stock from factory. There are a few aftermarket ECUs that you can buy though.

On that particular vehicle it won't make too much difference. You can tune the crap out of it, but it won't increase torque or horsepower by much.

In general from my experience the only time people tune stock or naturally aspirated vehicles is to fine tune their power output. Some Hondas actually grab some good power from an aftermarket tune. The Hyundai Delta and Lambda engines benefit decently from an aftermarket tuning as well. You would usually see naturally aspirated aftermarket tunes on vehicles that have ITBs (individual throttle-bodies), lightweight pulleys, lightweight clutch and flywheel, "Cams".

If your car is literally just a stock engine, you wouldn't really gain too much power. If it had a turbo that came with it stock, that's a different story. This is purely from a perspective of cost versus power. It's just not cost effective if you don't want to do more work to it.

If you're going to throw a turbo or supercharger in it, or do some VERY serious engine work; It's worth it. Haltech and MegaSquirt make affordable ECU's. You have to wire them in yourself though, so if you're not too familiar with work like that I would avoid doing it yourself.

If you want a little extra noticeable performance, I would try some of the other things I mentioned above. If you're satisfied with that and want more, throw a turbo in there. If you're not interested in racing, there are alot of other things you can do to increase power that don't involve HOURS of wiring and hundreds of dollars.

If you're wondering about cost V.s. labor V.s. increase in performance, let me explain a little bit.

You can port everything that involves the intake, which will cost you around $150. You can get lightweight pulleys, which depending on the rarity of them may cost you around $40 - $80 usually.... There are extremely cheap exhausts that serve the same purpose as expensive ones. I've seen them usually around $200. You can get cold air intakes around $60 (Which is a topic of it's own).

Those are the things you could do that would increase power and response noticeably. All of that combined would probably be the same as the ECU and most likely yield more power and response. If you add all of that up you're going to spend at most $600 for a decent gain. If you buy an ECU, you'll spend $900 for VERY little. The plus side of this is that if you spend the money ahead of time doing these things, when you do decide to upgrade your ECU; It will be able to utilize the engine even more so.

As far as time for installation, if done in a single day by someone who knows cars decently; It should only take a couple hours at a time. The porting and polishing of your intake runners and heads will take a while, but it's something you can do yourself. You just need some soft Dremel attachments and some youtube videos lol.

Most of it's easy to do. If it was me on that particular vehicle, I would get all of the fun stuff first. Once you have all of it then tune it liberally =)

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  • I have to agree, if the engine has forced induction then there is some hope , on a N/A all you can do is port the air filters/swap intake exhaust manifolds to be reasonable. although porting pistons are being done by idiots.
    – Shobin P
    Jan 13 '16 at 15:56
  • Yeah generally thats a full engine rebuild. My Hyundai Tiburon has... Lightweight EVERYTHING. Ported intake, modified cams, and a little larger exhaust. All of this combined took her from 178HP to around 230HP. Was it worth it for me? Yes. I had the money. Could I have bolted on a supercharger and gained 200HP, yes but I wanted to do it just because. If you have the money and want to make it a racecar, an ECU would be a good start. If not, invest in some smaller stuff =P
    – cloudnyn3
    Jan 13 '16 at 16:03
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    This is all excellent information. I didn't realize how important the difference was between natural aspiration and port induction. That being said, can we get a little closer to quantifying "not much benefit" and a "cost a lot?" Are we talking about a handful of horsepower, or a few dozen? Are we talking about $120 and 30 hrs of work, or are we talking about $20 and an afternoon? Not trying to be precise, just ballpark. Also, the information about the benefit coming from other mods is really useful. That helps inform the cost a bit.
    – Matt
    Jan 13 '16 at 16:42
  • @Matt Piggy back ecu's might be somethin worth looking into. They don't cost much as they work in conjunction with your ecu. Standalone ecu's will be more expensive and only make sense when other upgrades are in order. Even then, if only fueling and ignition timing is to be changed, piggyback ecu's can do the job. They also can be removed anytime you want , and are not permanent (warranty issues). Depending on the vehicle, you could actually get decent gains. Some of them even have variable modes to suit various driving requirements.
    – chilljeet
    Jan 14 '16 at 12:17
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    Beware, the "Conservative tune" that you speak of is also what keeps the vehicle compliant with emission regulations. You must check if the remap offered by the piggy back keeps you within your area's emission regulations.
    – chilljeet
    Jan 14 '16 at 12:18
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As I understand it, a "performance" tune for an unmodified, normally-aspirated engine basically consists of a slightly more aggressive ignition advance curve and a higher (200-500 RPM) redline. Depending on your engine you might see some single-digit horsepower gains, but IMHO it's not worth it for the $200+ you'll spend.

In your case, I'd honestly only consider a new tune to accommodate other changes you've made to your engine (better intake/exhaust, bigger injectors, etc). These are things that will probably be outside the stock ECU's ability to compensate for, so a tune will be required in that case anyway.

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