Reset ECU...?
 

I have about 4K miles on my BRZ, have very much enjoyed the car but also on the lookout for performance improvements. Over in the engine mod section of the forum I saw a post where a guy recommended resetting your engine control unit after break-in. Said this could be accomplished by disconnecting your battery for 20-30 seconds.

I guess this would cause it to 're-learn' your engine and be a more accurate representation seeing as how the motor does behave differently after it is broken in. He claimed he saw a nice improvement. There are a lot of posts over there about flashing your ECU to get more out of the car, but it is not cheap. You can easily spend $800.

I don't know if 'resetting' really helps but I tried it, and after a few days the car does seem more lively. But its purely subjective. Would someone else try it and see if you notice anything?

I dunno, 20-30 seconds doesn't seem like the norm. I don't claim to know the magic number but I've always had better luck waiting at least 5 -10 minutes.
I've been able to accelerate the process by cycling something like lights, or horn that would draw the most to purge any remaining power in the capacitors on the ECU.

To me, the most important thing is making sure the power has been purged from the circuitry. It might be instant from that point but I like to be sure.

Everytime you add any kind of bolt on performance mod ex. CAI, SRI, cat back, etc. you should reset your ECU to re-learn the new system, you can accomplish this by either un hooking the battery or simply taking out the fuse for the ecu for 5-10 minutes. Easier option honestly.

Thanks for that advice! So I should disconnect power to the ECU for longer than what I had done. I am looking at the fuse layout diagram on the inside of the fuse box cover. Is it a 7.5A fuse labelled ECU-B?

How long does it take the ECU to re-learn after having done this?

Theoretically, as soon as you disconnect the fuse, it will reset. I just disconnect for 5 - 10 minutes just to be on the safe side. It will take 50 to 100 driving miles for the ECU to "re-learn"

I'm a shop owner and have been tuning Subarus for ten years. The ECU learns and responds very quickly -- changes in fuel or timing happen in MINUTES, not hours. That means it does NOT matter if you reset your ECU or not. The car will adjust to any new parts (if there are any adjustments to be made) quickly and automatically.

You do not have to reset your ECU, and it won't accomplish anything if you do because the car will get to the same end-point one way or another.

--Dan
Mach V

Ecu is cool

Dan you are raining on the parade, lol. I'll take your word for it though, sounds like you know what you are talking about. I see various ECU 'tunes' for sale now. I get the impression that these are essentially replacement table entries that tell the ECU what to do when it sees the corresponding set of conditions? What is your opinion on that kind of mod? It isn't cheap, and looking at the dyno comparisons I am not see a lot of difference.

Capstan- the ECU must always monitor and adjust for various parameters. If it was unable to detect and adjust to changing conditions it wouldn't be doing its job. There is no reason to manually reset as the CPU is always detecting and responding several times per second.

A tune is just a new set of rules, instructions on what amount of fuel to spray for a specific amount of air metered in the MAF sensor, temperature, fuel octane etc.

The idea is that a tune will give the instructions beyond the safe conservative factory's. and of course the factory doesn't give rules for more air flow, less restrictive back pressure etc.

I think a tune is a logical step AFTER all your bold ons are in place if you don't mind spending $850 plus for that extra enhancement. I have never had a tune done but look forward to doing it eventually.

If you're not doing it to support some kind of forced induction or alternate fuel (like E85, race gas, or methanol injection), it probably is not going to be worth the cost, in my opinion.

Actually, the stock ECU program DOES have rules for more air flow, up to a point. But you're right, a revised ECU tune will generally alter the settings for fuel and ignition timing with the goal of increasing power.

--Dan
Mach V

We bought a stage one built 2012 Toyota 86 fa20 and swapped it into our 2014 Subaru brz. The stage 1 engine also came with a Revolutios rp600 kit and a Garrett gtx3076r turbo, turbosmart wastgate and BOV, EL turbo manifold,dw1100 injectors, Aem 340lph high flow fuel pump,delicious tuning flexfuel kit, Setrab thermostatic oil cooler, mishimoto intercooler,grimspeed EBCS. We got the engine in and all hooked up, did a oft tune for increased injectors, fuel pump, 1 o2 sensor. The car will run, but it fels like its not getting enough fuel. there is zero throttle response the engine will die if I touch the gas peddle. Help please if you have any ideas. p.s my son is a active duty soldier and is being deployed on Tuesday, we did this swap two weeks ago and engine still wont run. So this is now MY problem to deal with.

Running a OTS tune on a fully custom engine is a good way to blow it up.
Find someone to provide a custom tune.