Well I'm hoping I can get it from a VW dealer for free...
Surely it makes no difference whether you disconnect +ve or -vecraig-pd130 said:
reset ecu is a must
- Thread starter chillcupra
- Start date
True, it doesn't, but I have read that it's safer to disconnect the -ve rather than the +ve. Dunno why ....
On a Leon it's definitely easier to do the negative - there's less attached to it - well on mine at least
You should always disconnect the Negative/Ground...
It requires a spanner to loosten the connections say. If you undo the +ve and accidentally hit the spanner onto something conductive acting as a ground - BANG - youve made yourself an arc welder and a firework! Do this to the -ve and there will be no electron flow. Its from a safety point of view as theres plenty of fuel, sensetive electronics and metal in the engine bay.
Play safe
It requires a spanner to loosten the connections say. If you undo the +ve and accidentally hit the spanner onto something conductive acting as a ground - BANG - youve made yourself an arc welder and a firework! Do this to the -ve and there will be no electron flow. Its from a safety point of view as theres plenty of fuel, sensetive electronics and metal in the engine bay.
Play safe
I'm going to have to reset mine tonight, it's been in 'town drive' mode for the last few months .... just feels like it's slowing down a little.
Fair enough, you do get BIG sparks when you undo the +ve with a metal ratchet and drop the handle onto the -ve
Think it will depend on how extreme the driving conditions are after reset ... I'm trying to make sure it gets a bootful on most journeys so it doesn't get too complacent
I removed the fuel temp sensor resistor mod box from mine a couple of months back, so a reset was probably a good idea to sort that out.
Oddly, I did some in-gear accel figs last night and the car was only two-tenths slower ( 40-60mph in 4th ) than with the tuning box ...
I removed the fuel temp sensor resistor mod box from mine a couple of months back, so a reset was probably a good idea to sort that out.
Oddly, I did some in-gear accel figs last night and the car was only two-tenths slower ( 40-60mph in 4th ) than with the tuning box ...
tan159753
Guest
Although I am quite happy with my average return of 55mpg, cant really feel the woosh of the turbo and car seems a bit sluggish.
If this is more or less optimum economy for my engine and i dont want to race it around a lot of the time, should i do a reset?? Worried my mpg will go down.
If this is more or less optimum economy for my engine and i dont want to race it around a lot of the time, should i do a reset?? Worried my mpg will go down.
I left mine for about 15 mins then drove it straight away, felt a bit sluggish afterwards to be honest. Maybe 15 mins isnt long enough?
Hmm, I'm wondering if somebody disconnected your battery without telling you i would bet no one would notice. This could be a tell someone there is alcohol in their drink when there isn't and watch them get drunk scenario LOL. When i replaced my gearbox last week the battery was out for a whole day and with my car made no difference whatsoever.
You should always disconnect the Negative/Ground...
It requires a spanner to loosten the connections say. If you undo the +ve and accidentally hit the spanner onto something conductive acting as a ground - BANG - youve made yourself an arc welder and a firework! Do this to the -ve and there will be no electron flow. Its from a safety point of view as theres plenty of fuel, sensetive electronics and metal in the engine bay.
Play safe
Not sure your right about that TBH. If you disconnect the live or +ve, there is no power going around the car as the lead isn't on the battery and no power will leave the negative, but if the negative is off then all the live power is going through the car and wanting to leave through the negative terminal. If this hits metal, the sparks will start and then you may have the problems (arc welder etc).
I could be wrong, but thats how i understand it
Back on topic, it's well worth resetting the ECU and cleaning the air filter once in a while. I try and do mine once a month to keep it running better.
Here's something I read recently that you guy's might find interesting, it makes a lot of sense to me.
ECU Reset
Definition
The ECU "learns" about your engine as you drive the car. The "learning" is actually a process that the ECU uses to track the tolerance changes of the sensors and actuators on the engine. Two examples of these values are the position of the idle-air bypass valve (automatic choke) at idle with the A/C on, and the trim gain on the injectors. The ECU stores these "learned" values in battery backed-up RAM so that it doesn't have to start from scratch the next time you turn your engine over.
"Resetting the ECU" is the process of clearing all the long term memory from the ECU's memory. These variables trim idle speed, fuel, spark, and more. The ECU will also store trouble codes for diagnostic capability. By resetting the ECU, the trim values will be set to some neutral default value and all of the trouble codes will be cleared.
How-To
To "reset" the ECU, all you have to do is remove the source of backup power. To keep the memory alive while the car is off, the ECU has a direct line, through a fuse, that goes right to the battery. This is usually the same line and fuse that supplies backup power to your radio so it doesn't forget all of its settings. Sometimes people like to pull this fuse when they are working on or cleaning the interior of their car. This fuse also controls the lights that go on when you open the door, so many pull this fuse so they don't drain the battery during their job. However, this will also cut backup power to the ECU.
Myth
There is quite a bit of mythology revolving around resetting the ECU. Many people mistakenly believe that they need to reset the ECU after installing major engine modifications. Others believe resetting will resolve engine problems. Neither are correct.
Reality
The ECU is always tracking the engine's sensors and actuators. Resetting the ECU does not cause the ECU to learn engine changes any faster. The ECU is always tracking the gradual changes in the engine sensors and actuators. The ECU never gets satisfied with a setting, and is always updating the trim values. It will discover whatever change you made to your engine and make the appropriate changes. In fact, unplugging the ECU will most likely increase the learning curve of the new part.
I reset the ECU, and now the car runs rough! Why? The engine may run rough or idle poorly right after ECU reset. The ECU now has default numbers in its trim memory - it has to adjust them to match the tune of your engine and its sensors and actuators. It might take a day or two of driving in traffic before the engine will settle down again. Now you know why the ECU remembers these values in the first place!
ECU Reset
Definition
The ECU "learns" about your engine as you drive the car. The "learning" is actually a process that the ECU uses to track the tolerance changes of the sensors and actuators on the engine. Two examples of these values are the position of the idle-air bypass valve (automatic choke) at idle with the A/C on, and the trim gain on the injectors. The ECU stores these "learned" values in battery backed-up RAM so that it doesn't have to start from scratch the next time you turn your engine over.
"Resetting the ECU" is the process of clearing all the long term memory from the ECU's memory. These variables trim idle speed, fuel, spark, and more. The ECU will also store trouble codes for diagnostic capability. By resetting the ECU, the trim values will be set to some neutral default value and all of the trouble codes will be cleared.
How-To
To "reset" the ECU, all you have to do is remove the source of backup power. To keep the memory alive while the car is off, the ECU has a direct line, through a fuse, that goes right to the battery. This is usually the same line and fuse that supplies backup power to your radio so it doesn't forget all of its settings. Sometimes people like to pull this fuse when they are working on or cleaning the interior of their car. This fuse also controls the lights that go on when you open the door, so many pull this fuse so they don't drain the battery during their job. However, this will also cut backup power to the ECU.
Myth
There is quite a bit of mythology revolving around resetting the ECU. Many people mistakenly believe that they need to reset the ECU after installing major engine modifications. Others believe resetting will resolve engine problems. Neither are correct.
Reality
The ECU is always tracking the engine's sensors and actuators. Resetting the ECU does not cause the ECU to learn engine changes any faster. The ECU is always tracking the gradual changes in the engine sensors and actuators. The ECU never gets satisfied with a setting, and is always updating the trim values. It will discover whatever change you made to your engine and make the appropriate changes. In fact, unplugging the ECU will most likely increase the learning curve of the new part.
I reset the ECU, and now the car runs rough! Why? The engine may run rough or idle poorly right after ECU reset. The ECU now has default numbers in its trim memory - it has to adjust them to match the tune of your engine and its sensors and actuators. It might take a day or two of driving in traffic before the engine will settle down again. Now you know why the ECU remembers these values in the first place!
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Not sure your right about that TBH. If you disconnect the live or +ve, there is no power going around the car as the lead isn't on the battery and no power will leave the negative, but if the negative is off then all the live power is going through the car and wanting to leave through the negative terminal. If this hits metal, the sparks will start and then you may have the problems (arc welder etc).
I could be wrong, but thats how i understand it
Back on topic, it's well worth resetting the ECU and cleaning the air filter once in a while. I try and do mine once a month to keep it running better.
I am afraid the other man was right.
ALWAYS disconnect the negative first and reconnect last - for the safety reasons explained (a spanner going from +ve to chassis will generate enough current/heat to hurt you and damage car parts). The chassis and negative terminal are at same potential, so you will be safe.
Dont think because the +ve is left connected the whole car & chassis floats at 12v - it wont. Current flows from -ve to +ve, so your car remains safe with no current flowing or ability to make it flow. When you reconnect the -ve, you may see a very small spark from the current required to maintain the idle functions (ECU backup, clock, radio backup etc) -- however you'll see the same small spark if you connect the +ve last.
I don't get this.... if you reset the ECU and it learns on driving style which is constantly updating the ECU, surely it will learn and adapt back to how it was previous to the battery disconnection? I have tried this on my Leon, and initially the car felt more responsive and a bit rough on idle, but after a few days it was back to normal and the same as before...
It may depend on what the ECU learned before the reset.
For example, I had a resistor-in-a-box on the fuel temp sensor for 5K+ miles, then removed it. The car is deffo sharper after the reset, and continues to be after 50+ hours driving.
For example, I had a resistor-in-a-box on the fuel temp sensor for 5K+ miles, then removed it. The car is deffo sharper after the reset, and continues to be after 50+ hours driving.
I agree with what Andy posted - this makes bugger all difference, it made mine and Mike_OBD's car feel worse for 10 minutes and then felt the same thereafter.
The ECU is CONSTANTLY adapting the fuelling, boost etc. Itd be somewhat dangerous if it adapted to economical driving and then gave you less power when you needed it.
When you have a remap done, it takes upto 1hour or so of driving for the map to fully adapt. This is due to the short term trim levels so i doubt an ECU reset would make the car feel defferent for much longer then that!
The ECU is CONSTANTLY adapting the fuelling, boost etc. Itd be somewhat dangerous if it adapted to economical driving and then gave you less power when you needed it.
When you have a remap done, it takes upto 1hour or so of driving for the map to fully adapt. This is due to the short term trim levels so i doubt an ECU reset would make the car feel defferent for much longer then that!
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