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Reseting the ECU



Iv been reading about reseting the ECU by disconecting the battery. Does this work? If the cars been re-mapped will this erase it?

Sean
 
  172
no idea dude but i doubt it would,isnt there a battery in there?
im probly talking sh1te tho so take no notice!!!
(here to be proved rong tho!!!)
 
  BMW M4; S1000 RR
lol mate. If only.

If you want to get rid of a map, then you'll need to put the original back on (whoever did the remap should have it). Renault could also do it I suppose but they would probably just charge you for a new ECU.
 
  Carrera 4S. Clio 172. M5
How do you mean, reset. If you mean disc. the battery, that wont re-set anything but your clock.
 
  182 Trophy
I think what he's saying is that by disconnecting the battery for a short period of time, the ECU resets itself. That doesn't mean re-program itself just resets, so the map stored on the EPROM chip remains the same.
I am lead to believe that this 'resetting' allows the ECU to re-learn your driving style. I think it does this by making very minor changes to the fuel air mixes. Thus, you may get slightly better engine response from 'resetting' the ECU. But as someone quoted on CS in another thread: Unless you drive around like Alonso, it will just revert back to the slightly more conservative fuel-air mixture settings...The guy who quoted that (sorry cnt remember who it was) also said it's worth doing before trackdays.
 

MRBILLYUK

ClioSport Club Member
  FF Jeden Osiem Dwa
^^^ Sounds right to me . When i fitted a k+n apollo air filter to my 182 it said disconnect the battery for 30 mins . I didn't and the car came to a halt and had to be towed home by the AA . So i rang k+n and spoke to a guy in the R & D department . He told me i should have disconnected the battery as per instructions . So i did and after that the car ran ok , except for losing the 5k kick . So i binned the filter not long after and fitted a custom one .
 
  RSC 182 Cup
Im the fella that mentioned the ecu reset trick. Its something we've talked about a fair bit at ozrenaultsport.com.

Basicaly, it seems that when you reset the ECU it changes all the variables that it "learns" back to their factory default. That seems to mean a snappier A/F mixture which increases throttle response (quite dramaticaly if you drive concervativly day to day). It will then begin the process of learning new values to suit your driving style (these changes are very minute, its not like a remap). Apparently the biggest advantage to reseting the ECU is that it will , to an extent, take into account any mods you've made, such as custom IK's.

For me its only something I do for a laugh or at a trackday.

Oh, and MRBILLYUK, the K&N Apollo standard induction piping is crap, its way to narrow and long. Ive fitted a larger diameter pipe to mine which is much shorter and runs a very efficient, direct path to my nominated cold air point. It made quite a noticable difference including the return of the 5k kick. Something to keep in mind.
 
  Carrera 4S. Clio 172. M5
Well, thats all news to me. I have just scoured the Renault workshop manual fault finding section and the is nothing in there that confirms this.

It may be some half baked rumour built on the cars fault diagnostic code log that the clip can read, but I will bow to superior knowledge if Edde or Fred are around.

I know such driving pattern logs exist on some cars like the M5 and M3 csl but i wasn't aware that Renault had adopted this on their RS models.
 

MRBILLYUK

ClioSport Club Member
  FF Jeden Osiem Dwa
Im the fella that mentioned the ecu reset trick. Its something we've talked about a fair bit at ozrenaultsport.com.

Basicaly, it seems that when you reset the ECU it changes all the variables that it "learns" back to their factory default. That seems to mean a snappier A/F mixture which increases throttle response (quite dramaticaly if you drive concervativly day to day). It will then begin the process of learning new values to suit your driving style (these changes are very minute, its not like a remap). Apparently the biggest advantage to reseting the ECU is that it will , to an extent, take into account any mods you've made, such as custom IK's.

For me its only something I do for a laugh or at a trackday.

Oh, and MRBILLYUK, the K&N Apollo standard induction piping is crap, its way to narrow and long. Ive fitted a larger diameter pipe to mine which is much shorter and runs a very efficient, direct path to my nominated cold air point. It made quite a noticable difference including the return of the 5k kick. Something to keep in mind.

I sold the apollo cos it was crap imo , plus i sold it for more than i paid for it ;) . The surface area of the filter is less than that of the standard panel filter . I now have a k+n cone filter inside a custom made aluminium airbox , the car pulls like a good un now and still has the 5k kick :)
 

MRBILLYUK

ClioSport Club Member
  FF Jeden Osiem Dwa
Well, thats all news to me. I have just scoured the Renault workshop manual fault finding section and the is nothing in there that confirms this.

It may be some half baked rumour built on the cars fault diagnostic code log that the clip can read, but I will bow to superior knowledge if Edde or Fred are around.

I know such driving pattern logs exist on some cars like the M5 and M3 csl but i wasn't aware that Renault had adopted this on their RS models.

I could reset the ecu on my old Pug 306 S16 this way .
 
  RSC 182 Cup
TO THOSE WISHING TO TRY THIS WITH A STOCK STEREO HEADUNIT. ONCE RESET YOU WILL NEED TO INPUT YOUR HEADUNITS SECURITY CODE FOR IT TO WORK AGAIN. I would hate to stuff anyone up.

Apart from that go nuts.
 

Tom

ClioSport Club Member
  i3
Well, thats all news to me. I have just scoured the Renault workshop manual fault finding section and the is nothing in there that confirms this.

It may be some half baked rumour built on the cars fault diagnostic code log that the clip can read, but I will bow to superior knowledge if Edde or Fred are around.

I know such driving pattern logs exist on some cars like the M5 and M3 csl but i wasn't aware that Renault had adopted this on their RS models.

News to me too.

The siemens sirus ecu used in the 182/172 has predefined settings as far as i was aware.
 
  Polo GTi
No idea myself but Nick hill did tell Chris n Nic to do it on their Cup when it
was playing up, think it worked too? Although f**k knows
 

Gaz_

ClioSport Club Member
  Extreme mode
Cant see it myself, its all a myth imo. The ecu can't think for its self, ie 'learn' .......it will adjust things like mixtures from inputs like o2 sensors/airflow sensors etc
 
  Polo GTi
Yeah I dont reckon it learns, think the scenario was something along the lines of a "thing" was banging around in the bay as it was loose, said item was sorted, nick recommended resetting the ecu as the banging might of disturbed a sensor, unpluggin the ecu would clear down the fault that would of been flagged on the ECU. End result it was running better

When I had a faulty TPS on the Williams I replaced the throttle body, but the error was still there on the clip at renno, quick unplug of the battery and all was sorted.

Hope I didnt baffle you with the techincalities ;)
 
  Nippy white cup
Yep defo made a difference to mine. The fuel rail cover was slightly loose which Nick said might have made a sensor think there was a'knock' and the ecu alters to stop any damage (iirc). Before this me and Monkey had a comparison on a private stretch and it was quite even then he would pull slightly. I did the reset a week or so later and tried again but this time my car was defo a bit quicker. Also my times dropped at York as well. Don't know the technical reasons but i know it worked.

Chris
 
  Polo GTi
Well I for one, dont believe it, sorry :dapprove:

Believe what? Self Learning or Chris's car responding after an unplug?

Doesnt matter to me, but like I said I dont believe it was self learning, more to do with resetting errors flagged up on the ECU possibly.

The Nana was the same albeit a diff ecu, running well on for a while on the SMT6, then went sluggish, that was very, very noticable, quick unplug and it was back up to speed, not the same I know but that benefitted from an unplug.

No idea about the science behind it, but it was definate, not the differece between 95 or 98 ron noticable, it actually was noticable.
 
  Nippy white cup
Yep made a difference 100%...pulled harder to the red line etc. and as you said it used to work on the Nana everytime so can't have been coincidence imo

Chris
 
  RenaultSport clio 172 mk2
Psycho is I understand correct. This has come up on this forum before. one of the Renault experts explained it.

Here's my recollection. I'm not an expert on automotive ECUs, so it may not be precisely correct, but this is the general idea.

There is map in flash ROM that only changes if it is rewritten through the OBD-II port with appropriate software, or the ROM chip is removed from the ECU and electrically overwritten. That's the map that's changed if your car is remapped.

But as well the ECU has a table of values stored in RAM that it learns from feedback from the lambda sensor in the exhaust that can add to or subtract a small amount from the values in the map. So if your engine consistently breathes a bit better at certain revs than the standard ECU map was programmed to expect the supplementary map will record a value that says add a bit more fuel. The result is that if you make small, repeat, small, modifications to your engine the ECU will adjust for them. Resetting the ECU, ie removing power from it for a while, wipes that supplementary table, and the ECU goes through the learning process again.

In certain circumstances, like you complaining about a problem, a dealer may look at the values in the supplementary map to help diagnose what the problem is. That's where they can notice that your car has been remapped. That suggests to me that how it was explained to me wasn't actually correct, that what's actually done is that when the ECU is cold booted (reset) the ROM map is copied into RAM then as the car is driven the values in it are adjusted based on feedback from the lambda sensor.

If the ECU can read what amount of fuel it needs from the lambda sensor why bother with a map at all, you say? Lambda sensors can't always be relied on. And they have to be ignored in some circumstances. And they wear out. So the ECU has to have a map it can rely on when it goes into open-loop mode, and it can only make small incremental and gradual adjustments to that map based on the lambda sensor disagreeing. So if you make a change you have to do an ECU reset so it goes into learning mode.
 
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  RSC 182 Cup
Theres a guy on our forums with a Spyder and he has fit a battery cutout switch to the dash just for reseting the cpu if I recall correctly. He did alot of trackdays judging by his photos so it was probably a good tool.
 
R

rich[182]

Can any of the tuners who carry out remaps confirm all this resetting the ECU stuff ?
Ta, Im curious
 
  106 GTi
The whole ECU reset is a fave, for the 306 GTi 6 ownser over on there forum - the first port of call for any issues over on there site.
 
Yep , ive come over from 306gti owners, i'm thinking a ecu is pretty much the same in any car, over time it picks up bad habits, like if youve had some problem it will learn to cope , or if the person who had the car before you drove at 20 mph everywhere , it will think thats the norm!
The bloke who had the car before me used to put standard fuel in it, now it dines on vpower , so when i do a ecu reset it will learn to get the max out of the better fuel.

Just think of a computer, when you do a system restore, and take it back to factory settings it cleans up all the broken code/links , and it runs smoother, and quicker!

leon
 
  RSC 182 Cup
Disconnect the negative lead to the battery and leave it for half an hour. Reconnect and enjoy!

Oh, but be aware that if you have a stock radio you will need to input a security code before it will work again. You can get the code from your dealer.
 
Just disconect the battrey for 20 mins or so, re-conect it , turn on all your, electrics , lights , wipers, fan's, to get the altanator runnin, then take it for a 15 min blast ( not in rush hour ) it will pick up your driving style, and cure any niggling idal issues.
 
  BMW M4; S1000 RR
lol what a load of b****cks.

When you remap a car, you're basically editing the fueling instructions on the computer's ROM (Read only memory for the fuckwits out there:)), you can take your battery out, throw it off a cliff, take a bus to Halfords and buy a new battery, plug it in, reset your code, but it won't reset the map.

This "Learns how you drive" stuff is a load of crock too. What exactly is it meant to change ?? You're trying to say that if you "reset your battery" then you can just blat the pants off your car and it will give you more power ?? Don't think so..
 


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