How do you reset the ECU on a NB

Nickf · Post by **Nickf** » Thu Sep 13, 2007 10:39 am

Hi

Anyone know how to reset the ECU on my NB (10AE)? I assume you just unplug the batttery for quarter of an hour or so but someone must know for sure.

The plan is to run a tank of 98 through next trackday. I know that is a controversial idea but apparently to give the best chance of any gain the timing needs to be reset.

Thanks

Nick

Anthug · Post by **Anthug** » Thu Sep 13, 2007 4:24 pm

Hi,

Found this on www.miata.net

1) Disconnect negative battery cable.

2) Depress and hold brake pedal for 30 seconds.

3) Reconnect negative battery cable.

Regards,

Anthony

Nickf · Post by **Nickf** » Sun Sep 16, 2007 10:41 pm

Thanks. But I wonder why you have to press the brake? Seems odd.

Post by **jif** » Sun Sep 16, 2007 10:53 pm

I believe it's to drain any residual power being stored in capacitors etc which might keep the ECU memory alive

Post by **zorruno** » Tue Sep 18, 2007 12:40 am

I guess as jif said this is the easiest way to drain any remaining power in the supply to the ECU (could just as easily use headlights/horn I suppose) - but this is interesting considering that I would have thought the brake lights wouldn't complete a circuit without a key in the ignition?

Do the brake lights work without a key?

(My Haynes manual is on loan so I can't check - and I'm not by my car...)

Grant · Post by **Grant** » Tue Sep 18, 2007 8:25 am

Just checked my 1998 NB. The brake lights do come on without the key in the
ignition.
Don't think I've come a cross a car where the key was required to enable the
brake lights.

Post by **zorruno** » Tue Sep 18, 2007 11:17 am

on 18/09/2007 8:25 a.m. Grant wrote:

Just checked my 1998 NB. The brake lights do come on without the key in the
ignition.
Don't think I've come a cross a car where the key was required to enable
the brake lights.

well that answers that then

I just checked my OTM and yes, it is the
same.

Thanks Grant

poison · Post by **poison** » Tue Sep 18, 2007 7:03 pm

zorruno wrote:....I just checked my OTM....

Stop showing off... what the hell is an OTM????

Other Terrific Manual....?

Old Trusty MX5....?

Outdated Terrrible MX5...?

We'll probably have to start a new thread just for more OTM possibilities I'm sure will get posted.

Ian · Post by **Ian** » Tue Sep 18, 2007 7:26 pm

Old Timers Memorybank?????

Post by **zorruno** » Tue Sep 18, 2007 8:53 pm

poison said on 09/18/2007 07:03 PM:

... what the hell is an OTM????

In my case a commodore, but YMMV.
IAC, & thanks to Paul Williamson there is a good list here IIRC...
http://www.photec.com/home/Williamson/acronyms.htm

...YW

(Search ref: MX5 Miata Acronyms)

Nickf · Post by **Nickf** » Thu Sep 20, 2007 11:21 am

That is interesting and helpful! The track day is three weeks off, so i will report on the BP Ultimate/resetting ECU combo afterwards.

Nick

Nickf · Post by **Nickf** » Wed Nov 28, 2007 3:31 pm

Just remembered i didn't report back. Frankly I can't tell the difference on the 98 Octane, but given you are only supposed to get an extra BHP or two anyway I suppose you wouldn't expect to. I will keep using it for track days tho- for the very minor extra it costs it seems worth it on the off chance it does make a difference.

poison · Post by **poison** » Wed Nov 28, 2007 4:16 pm

Sorry Moderator but I have to comment….

It’s a very common misconception that a higher octane fuel will give more power… sadly it doesn’t. But it does allow you to modify the engine for better performance by changing the ignition and/or valve timing, increasing the boost or compression (all within limits) without pre-ignition and engine damage. People often claim they could ‘feel’ the difference with the higher octane, and to them I suggest they give me a call I and I will sell them some $2000 ‘directional’ speaker cables so they can ‘hear’ the difference too. All just the placebo effect….

A few years ago a company in Italy (I think) invented and trialled a special under seat device that would make any car sound and feel like a Ferrari for the driver. Every single driver said the same car was much faster and handled better. The device never got off the floor as there were too many crashes due to the perceived extra performance and handling. It’s really the same as some people thinking red cars are faster… seriously please…grow up…think about it… clearly the white ones are faster.

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SLYDIT · Post by **SLYDIT** » Wed Nov 28, 2007 6:33 pm

cars with knock sensors such as the NB WILL definitly see a difference in performance as the ECU is always trying to run the most advanced timing it can get away with until it senses knock, then it backs it off....

tests done on a Gen 3 Holden V8 showed that the car run on 91 made not much more power than a V6 as it was knocking so bad...when run on 98 the power came back......now i always laugh at try hards putting 91 in thier SS commodores.....

Also even though 98 costs around 5% more..we actually get around 7-8% BETTER mileage from it, so it is ABSOLUTLY WORTH EVERY CENT!!!!

poison · Post by **poison** » Wed Nov 28, 2007 11:44 pm

Good point about the knock sensor, hadn't thought of that, but now thinking about it.... isn't the knock sensor like a safety valve in principle in that it backs off the timing quite severely in the rare occasion knocking occurs, and surely it shouldn't normally operate under heavy acceleration, otherwise when knocking occurred the power would suddenly die off. The knock sensor I believe is a digital sensor, in that it tells the ECU knock has occurred and to back off the timing NOW, therefore it's highly unlikely to provide accurate modulating control constantly fine trimming the timing for optimum performance. All IMHO as I can't comment further as I don't quite know enough about ECU's, although I'm a controls Engineer.

And the V8's... I used to have one (but sadly not the Gen 3) I was under the impression that these engines are designed for the higher octane, thus using the lower octane will inhibit the performance due to the knock sensor having to work.

Your point 3.... hmmm... no idea.

but then I do have to use 98 for other reasons...

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agent99 · Post by **agent99** » Sun Feb 03, 2008 9:26 am

Hi, I have always used premium in our 5 so can not comment on that, but I can say that our subie likes premium over regular every time. It may not make more power but hell it goes like a different car and returns far better mpg figures. All with out useing placebos! The difference is from stodgy to get up and gone. Where I found the biggest difference is on hill work 91 is not appreciated there. Cheers

Nickf · Post by **Nickf** » Thu Feb 21, 2008 10:07 am

I tried Ultimate again at the MX5 OC track day this month. Actually the car did feel like it was pulling better, both on the road and the track. And as well as the circuit laps I got from Tauranga and back on one tank, so it seemed like a success.

Trevor · Post by **Trevor** » Thu Feb 21, 2008 11:54 am

poison wrote:Good point about the knock sensor, hadn't thought of that, but now thinking about it.... isn't the knock sensor like a safety valve in principle in that it backs off the timing quite severely in the rare occasion knocking occurs, and surely it shouldn't normally operate under heavy acceleration, otherwise when knocking occurred the power would suddenly die off. The knock sensor I believe is a digital sensor, in that it tells the ECU knock has occurred and to back off the timing NOW, therefore it's highly unlikely to provide accurate modulating control constantly fine trimming the timing for optimum performance. All IMHO as I can't comment further as I don't quite know enough about ECU's, although I'm a controls Engineer.

And the V8's... I used to have one (but sadly not the Gen 3) I was under the impression that these engines are designed for the higher octane, thus using the lower octane will inhibit the performance due to the knock sensor having to work.

Your point 3.... hmmm... no idea. but then I do have to use 98 for other reasons...

[Posted via external email]

The most common form of knock sensor can be likened to a ceramic microphone, except that the sensed frequency is held very low by means of a weight which inhibits movement. The output signal is constantly available to the ECU as a means of controlling ignition timing.