ECU reset procedure [Archive] - Mitsubishi Lancer Register Forum

ECU reset procedure

michty_me
06-03-2014, 12:20
Hey all,

What is the best way to re-learn the fuel trims on an ECU?
My cars cold start was great for the past few months after getting some work done but I had a suspected lambda sensor fault (Excess fuel usage, P2253 codes, Thick smoke out the rear). I got this changed and decided to do an ECU reset to clear the fuel trims incase they had drifted with the excess fuel.

Now my cold start seems a bit erratic and the initial first drive of the day is a bit of a bugger (Before it was fine) a lot of spluttering and jerking about for a few hundred yards then it seems to calm down. AFR gauge is reading around 12.0 with occasional dipping to 10.0 but flashing so off the rich scale.

Once I get past the initial few hundred yards it is back to normal. Once it starts getting even slightly warmer it is fine, AFRís seem OK and drives quite smoothly.

This is how I done the ECU reset:

- I lifted the terminals from the battery for maybe two minutes.
- Reconnect battery and start then let it idle for about 10 minutes.
- Took it for a drive doing all types of driving.
- Stopped then let it idle again for 10 minutes and switched off.

Any other methods people would like to share?

michty_me
06-03-2014, 12:48
Just found this online related to the Evo X:

Open your bonnet, open the fuse box, pull out 7.5A number 2 fuse, this is battery backup for your main ECU, remove for 2 seconds, and replace. Your fuel trims and learned values on your ecu will now be reset.

Anyone any further input?

AndyF_RSX
06-03-2014, 13:29
After you've reset the ECU the 'usual' learning procedure is as follows:

1. Let car idle for 10-15mins with everything electrical switched off
2. Turn on full lights, heater on full hot, radio, fog lights, aircon etc. and then let car idle for 10-15mins

After this, the ECU will have learnt it's fuel trims.

The problem you might have is that if you have different injectors than standard then unless the deadtimes have been setup correctly when remapping the ECU might not be able to adjust the trims enough to get your fuelling to where it should be, especially when on cold start so it might need the ECU mapping looking at.

Andy

michty_me
06-03-2014, 13:43
After you've reset the ECU the 'usual' learning procedure is as follows:

1. Let car idle for 10-15mins with everything electrical switched off
2. Turn on full lights, heater on full hot, radio, fog lights, aircon etc. and then let car idle for 10-15mins

After this, the ECU will have learnt it's fuel trims.

The problem you might have is that if you have different injectors than standard then unless the deadtimes have been setup correctly when remapping the ECU might not be able to adjust the trims enough to get your fuelling to where it should be, especially when on cold start so it might need the ECU mapping looking at.

Andy

Hi Andy,

Thanks for the information. A bit different to the way I tried it the first time. I'll give that a try this weekend when I get some spare time and report back.

I would hope the map is OK, I believe two mappers worked on it over a few days to ensure all was spot on after I suffered an issue with a faulty injector last year.

I'll try yoour suggested method and see if it helps.

michty_me
07-03-2014, 15:58
Just a quick one, Should this be done when the car is stone cold?

falconer
07-03-2014, 17:39
Cam, I would do it cold, that way then the car is started from cold and warmed up. Im thinking of doing mine this weekend as I've been experience a bouncy idle and rev hang for a while. Just replaced the battery and will be throwing a new MAF at it soon to try and get it sorted.

Where is the fuse in the fuse box as may pull that as well, as I will be able to upload the MAP at anytime to the car.

michty_me
07-03-2014, 17:45
Cam, I would do it cold, that way then the car is started from cold and warmed up. Im thinking of doing mine this weekend as I've been experience a bouncy idle and rev hang for a while. Just replaced the battery and will be throwing a new MAF at it soon to try and get it sorted.

Where is the fuse in the fuse box as may pull that as well, as I will be able to upload the MAP at anytime to the car.

That's my thinking too mate.
I'll go ditch it round at my folks tonight so I can pop round and just fire it up cold in the morning. My neighbours may get annoyed with it sitting idling away for half an hour or so echoing off the buildings. :smthumbup

spikem
07-03-2014, 18:02
Just a quick one, Should this be done when the car is stone cold?yes so the car can re learn the cold idle. I done this once when the engine was warm and after that my tick over was always too low and hunting.

michty_me
07-03-2014, 20:49
yes so the car can re learn the cold idle. I done this once when the engine was warm and after that my tick over was always too low and hunting.

Awesome! Last time I done it I drove a few miles first and let it cool for 30mins but this time I've left at the place I'll be doing it so it will be cold cold cold!!

Do you just lift the battery leads for 10 mins or do you pull fuse 7 too as suggestion on evoxforums?

falconer
07-03-2014, 21:14
I normally just pull the neg off the battery, might be wrong, might be right, leave it for 10 mins at least. Then go through the procedure of idling then idle with load.

Noticed that you said fuse 7, thought the engine fuse was 2 & 7.5A. Might do both though

michty_me
07-03-2014, 21:46
I normally just pull the neg off the battery, might be wrong, might be right, leave it for 10 mins at least. Then go through the procedure of idling then idle with load.

Noticed that you said fuse 7, thought the engine fuse was 2 & 7.5A. Might do both though

Sorry yeah number 2 fuse. It was 7.5A.
I was going to pull the neg cable and fuse just to be certain.

spikem
07-03-2014, 22:16
Sorry yeah number 2 fuse. It was 7.5A.
I was going to pull the neg cable and fuse just to be certain.no, disconnecting the battery for 10 minutes isn't long enough, you can choose to either pull out the fuse, or you can totally disconnect the battery, get a single jump lead and connect one end on to the pos cable from the car and connect the other end of the jump lead to the neg terminal on the battery... this resets the ECU.

When you re-connect the battery and start up the car, you will know you have sucessfully carried out an ECU reset because once you turn on the ignition the car will switch on the AC, if you have the OEM Navi system you will also see that going through a visual reset.

Don't turn off the AC, let it do its thing for about 10-15 minutes, then go out in the car and drive it how you normally do, the ECU will then start learning the new fuel trims etc..

michty_me
07-03-2014, 22:30
no, disconnecting the battery for 10 minutes isn't long enough, you can choose to either pull out the fuse, or you can totally disconnect the battery, get a single jump lead and connect one end on to the pos cable from the car and connect the other end of the jump lead to the neg terminal on the battery... this resets the ECU.

When you re-connect the battery and start up the car, you will know you have sucessfully carried out an ECU reset because once you turn on the ignition the car will switch on the AC, if you have the OEM Navi system you will also see that going through a visual reset.

Don't turn off the AC, let it do its thing for about 10-15 minutes, then go out in the car and drive it how you normally do, the ECU will then start learning the new fuel trims etc..

I think thats why fuse 2 was suggested. Apparently it kills the backup to the ECU too so just needs to be pulled for a matter of seconds.

SO that is a different approach suggested so which is the best? Nigel said to me to disconnect, Idle for 10 mins or so then drive as normal then idle for another ten then switch off.
I obviously never reset properly as everything just started as normal. I only had the battery terminals off a few minutes.

spikem
07-03-2014, 22:44
I think thats why fuse 2 was suggested. Apparently it kills the backup to the ECU too so just needs to be pulled for a matter of seconds.

SO that is a different approach suggested so which is the best? Nigel said to me to disconnect, Idle for 10 mins or so then drive as normal then idle for another ten then switch off.
I obviously never reset properly as everything just started as normal. I only had the battery terminals off a few minutes.Yeah like I said, a few minutes, even 30 minutes is not long enough, best to do what I said or what Nigel said. I've done this many times Cam, I can assure you it is the best way. By applying a jump lead from the pos cable of the car to the neg cable on the battery (battery disconnected of course) purges the ECU of the fuel trims, fault codes etc...

You only have to do it for 1 second.

I do used to do this if I changed something like the exhaust or an air filter, BOV etc..

michty_me
07-03-2014, 23:06
Yeah like I said, a few minutes, even 30 minutes is not long enough, best to do what I said or what Nigel said. I've done this many times Cam, I can assure you it is the best way. By applying a jump lead from the pos cable of the car to the neg cable on the battery (battery disconnected of course) purges the ECU of the fuel trims, fault codes etc...

You only have to do it for 1 second.

I do used to do this if I changed something like the exhaust or an air filter, BOV etc..

Ok dokey! I'll give it a whirl tomorrow and see how I get on!

falconer
08-03-2014, 18:55
Did you do the idle relearn after mate? Which method did you use? Going to do mine tomorrow, think I will pull the battery neg cable and fuse 2 and then see what happens tomorrow.

Sent from a Galaxy

michty_me
09-03-2014, 04:28
Did you do the idle relearn after mate? Which method did you use? Going to do mine tomorrow, think I will pull the battery neg cable and fuse 2 and then see what happens tomorrow.

Sent from a Galaxy

No mate, I didn't have time. I had a wedding today and still have a bottle of red wine in my hand so I don't think it will get done at all soon

spikem
09-03-2014, 16:02
No mate, I didn't have time. I had a wedding today and still have a bottle of red wine in my hand so I don't think it will get done at all soon:lol:

michty_me
09-03-2014, 19:52
Pretty rough today like! Haven't moved far at all today!!

michty_me
12-03-2014, 13:31
I'll be doing this this weekend now. Nearly recovered from the wedding :lol:

Does ambient temperature matter when learning cold start fuel trims?
I've noticed during an afternoon after work I start up and it seems ok (Say 12 degC) but a cold morning like today or yesterday (1-2DegC) it seems a bit rough.

Fair enough I can't let it idle long at all cos I'm waking up the neighbours leaving the house as it is so its basically a jump in and go in the morning whereas leaving work I can leave it to idle a bit. Not ideal but you get the picture.

falconer
12-03-2014, 14:56
I would say so mate, when my cossie intake is stopped during my lunch break at home, the idle bounce is worse when leaving the house again.

Normally I can see intake temps ranging from 38c to 60c, when the idle is worse, its at high intake temp.

Although my idle is worse when putting electrical load on on the engine. So im still looking for reasons for this, just hoping its not my alternator.

Sent from a Galaxy

michty_me
12-03-2014, 15:06
Thats why I'm trying to do it on a cold morning and been left over night. Just to ensure it is correct.

If it didn't matter, I would have done it on my lunch hour when the car would be about 15 deg.
A cold winters day would be best then I guess.

falconer
12-03-2014, 15:37
I wouldnt worry about it to much mate, my reset will be done with an ambient temperature of 20c minimum at the moment, if i leave it the ambient temps are going to rise anyway. I normally leave it overnight and do it about 10.30 on a saturday

Sent from a Galaxy

michty_me
12-03-2014, 15:50
I wouldnt worry about it to much mate, my reset will be done with an ambient temperature of 20c minimum at the moment, if i leave it the ambient temps are going to rise anyway. I normally leave it overnight and do it about 10.30 on a saturday

Sent from a Galaxy

Ok no problem. I'll do it this Saturday morning/Lunch. Should be good enough.

michty_me
14-03-2014, 22:13
Spike, Is the ECU reset different on the X compared to the older models?

Forgot to add, My fuel trims appear to bounce around a fair bit on first start between -5% and 5% then slowly decreases and levels out between -0.5-0.5% when warm.

michty_me
15-03-2014, 16:11
Ok managed to do it today.

Removed fuse 2 and no reset happened.
Removed fuse 2, Fuse 5 and fuse 8 as they all had engine images in that bank :lol: and at the same time done what spike said with the battery and positive wire from the car. One of those worked as when I got in the car my current trip was back at 0.
Fired up and had everything off for 10-15 mins then had everything on for 10-15 mins, Went for a long drive after without switching off then sat and idled for 10 minutes and finally switched off.
Checked my trims and they are a bit all over the place. I know it takes a while to properly learn so will monitor over the next week or two and see what like.
Is it doesn't improve, I'll follow Spikes to the T.

gazza19800
15-03-2014, 20:42
My advice is stop resetting as we spoke leave for a few good days.
Cars trims where iirc +- less than 2 %
My gut feeling on this is there is another small issue somewhere else on the car.
Leave as is run and then ring me as we discussed after a few days.

michty_me
15-03-2014, 23:23
My advice is stop resetting as we spoke leave for a few good days.
Cars trims where iirc +- less than 2 %
My gut feeling on this is there is another small issue somewhere else on the car.
Leave as is run and then ring me as we discussed after a few days.

That was the only time I managed to reset it after the faulty Lambda Garry. Car will be left to run now. It seemed better this evening anyway. Will call you next week or so. I'll leave it to run and learn as you said on the phone.

Craigjdm
16-03-2014, 01:30
You can reset fuel trim using Evoscan as well can you not? Simple process of clicking 1 box?

michty_me
16-03-2014, 13:04
You can reset fuel trim using Evoscan as well can you not? Simple process of clicking 1 box?

God knows, I don't have any of that. I'll be leaving it for the time being anyway. See how I get on.

spikem
16-03-2014, 16:34
Spike, Is the ECU reset different on the X compared to the older models?

Forgot to add, My fuel trims appear to bounce around a fair bit on first start between -5% and 5% then slowly decreases and levels out between -0.5-0.5% when warm.sorry mate just seen this.

Ok managed to do it today.

Removed fuse 2 and no reset happened.
Removed fuse 2, Fuse 5 and fuse 8 as they all had engine images in that bank :lol: and at the same time done what spike said with the battery and positive wire from the car. One of those worked as when I got in the car my current trip was back at 0.
Fired up and had everything off for 10-15 mins then had everything on for 10-15 mins, Went for a long drive after without switching off then sat and idled for 10 minutes and finally switched off.
Checked my trims and they are a bit all over the place. I know it takes a while to properly learn so will monitor over the next week or two and see what like.
Is it doesn't improve, I'll follow Spikes to the T.The issue will be your after market injectors, it takes a while for the ECU to learn the new trims.

michty_me
17-03-2014, 09:17
Yeah that's what Garry said. They learn over time. I'm just leaving it for now to see how it goes. :smthumbup

Matt TRL
17-03-2014, 11:13
The best way to do a reset is disconect both plugs on the ECU for a few minutes, then reconect.
This will reset Long term Trims to 0. If its not right though it will just keep learing away and causing you issues. You will endup having to unplug the ecu evey week or so

The Evo X is a Biatch to map and get the fuel trims Right especialy with larger injectors and Maf Tubes. But can be done :smthumbup

Kind Regards

Matt

michty_me
17-03-2014, 11:29
The best way to do a reset is disconect both plugs on the ECU for a few minutes, then reconect.
This will reset Long term Trims to 0. If its not right though it will just keep learing away and causing you issues. You will endup having to unplug the ecu evey week or so

The Evo X is a Biatch to map and get the fuel trims Right especialy with larger injectors and Maf Tubes. But can be done :smthumbup

Kind Regards

Matt

I'll just leave it as is for now as discussed with Garry. When I first picked it up it was running perfectly. I changed the front 02 sensor and its gone a bit rough at cold start. I'm monitoring it for the next couple of weeks and if it still has an issue I'll pop down for a more detailed look.

Thanks for the info though. :smthumbup

Mr Ralliart
17-03-2014, 11:45
Mitsubishi standard is usually disconnect battery, then reconnect and 3 drive cycles to re-learn everything.

michty_me
17-03-2014, 14:41
Mitsubishi standard is usually disconnect battery, then reconnect and 3 drive cycles to re-learn everything.

That is why I reset it again this weekend.
I lifted the battery terminals a few weeks ago as requested by my tuner of choice and it never reset hence pulling the fuses and lifting battery power to kill all supplies to the ECU.

I believe there is a backup supply to the ECU on the X? Could be wrong.