Resetting the ECU

[NorCal_V]

Anyone suggest resetting the ECU after getting a cat back system? I just got a custom 2.25" system over the weekend. Not really noticing a big difference. In fact I think I may have killed some torque due to such low backpressure from the 2.25" pipe. Also does anyone know an alternative method to resetting ECU other than disconnecting the battery for like half a day?

Thanks! (In advance)

[Versafied]

I remember the first time I drove my old civic after installing intake headers and an exhaust that was 4" straight back, no cat with a downtube to a apex racing tip.. It was hilarious when I topped out at 90.. The torque band was completely different. And yeah, I suppose it was due to the entire lack of back pressure. Man it was such a great deep growl, I also got about ten tickets in three months for noise violation. Just glad none of them knew to look for the cat.. In Texas its a huge fine for removing the cat...

[Red Devil]

FYI, Just getting a catback and a CAI will probably only net you 5-10 hp. It doesnt really amount to anything.

What exactly do you mean by resetting the ECU? It wont really do anything in regards to the catback.

[NorCal_V]

It's my understanding that OBD II systems "learn" their settings after a number of miles. That would include learning to run, say, the a/f ratio at a certain, well at a certain ratio. Actually you seem to be some kind of guru. You should enlighten me.

[Scuba Steve]

Disconnect the (-) negative side of the battery for minimum of 30 minutes, the ECU will reset to default values and then it will re-learn your driving habbits, air intake, temp, etc.

[EZcheese15]

Here's the correct way to do it (article says Maxima, but it's the same on all throttle-by-wire Nissans):

http://www.nicoclub.com/articles.php?id=158458

But changing the exhaust should not affect the ECU unless you removed a cat. And even then, that would only be a temporary fix to clear the check engine light.

On a low HP 4 cylinder car such as the Versa, an exhaust is going to add very little HP. You're probably looking at the 3-4 HP range with a good exhaust. As a general rule of thumb, it takes approximately 10 HP to register on your butt dyno. You're only going to see 10+ HP differences with exhaust on larger engine cars, like V-8's. Not only do 4 cylinders have very little to gain with exhaust, but newer cars have even less. Factory exhausts these days are pretty free-flowing already.

[t19uz]

Here's the correct way to do it (article says Maxima, but it's the same on all throttle-by-wire Nissans):

http://www.nicoclub.com/articles.php?id=158458

But changing the exhaust should not affect the ECU unless you removed a cat. And even then, that would only be a temporary fix to clear the check engine light.

On a low HP 4 cylinder car such as the Versa, an exhaust is going to add very little HP. You're probably looking at the 3-4 HP range with a good exhaust. As a general rule of thumb, it takes approximately 10 HP to register on your butt dyno. You're only going to see 10+ HP differences with exhaust on larger engine cars, like V-8's. Not only do 4 cylinders have very little to gain with exhaust, but newer cars have even less. Factory exhausts these days are pretty free-flowing already.

hmm i already try your "correct way" but cannot work, any advise?

[EZcheese15]

hmm i already try your "correct way" but cannot work, any advise?

Use a stopwatch. The times in the procedure above are very exact and if you are a second off on any of the steps, it won't work. It might take a few times to get it right the very first time you do it.

[t19uz]

Use a stopwatch. The times in the procedure above are very exact and if you are a second off on any of the steps, it won't work. It might take a few times to get it right the very first time you do it.

WOWHOHO i've made it!!! yess using the STOPWATCH!!! thx a million bro........ it feels like ... finding a secret in a video game hahahaha....

anyway, so after reseting the ecu, now the ECU learn about my ride? i only change my fuel to a higher octane (95) and changing my rims into 235/40/18. The ecu learn this thing?

sorry for a dumb question.

[biggie]

ECU cannot learn about wheels/tires. Your speed sensor cannot adapt to different sizes.

It may help in Octane (but seems like you are way too high on Octane, depending on that engine), but if it changes anything it will not be enough for you to notice.

[t19uz]

oww so u mean that 95 is wasting money? so what is the proper octane for the MRDE18?

Thx in advanced.

[EZcheese15]

ECU cannot learn about wheels/tires. Your speed sensor cannot adapt to different sizes.

It may help in Octane (but seems like you are way too high on Octane, depending on that engine), but if it changes anything it will not be enough for you to notice.

His location says Jakarta. I'm sure they don't use the same R+M/2 octane calculation the states use. They probably use just the RON, which is roughly equal to 91 R+M/2 octane.

But t19, going back to what I said earlier, the ECU relearn will not learn anything different with a new exhaust, nor fuel octane, nor tire size, because none of those affect any sensors. Except for fuel octane, but that is done on the fly by reading the knock sensor and retarding timing if the octane is too low.

[EZcheese15]

oww so u mean that 95 is wasting money? so what is the proper octane for the MRDE18?

Thx in advanced.

Check the owners manual, and also check the fuel station to see which octane formula they use. It differs in each country how it is calculated.

[t19uz]

got it. Thx for the info.