V6 ECUs

lexi · Post by **lexi** » 29 Nov 2009, 12:26

If the battery is disconnected on V6 for any length of time how does ecu reprogramme itself. My battery was out but all seems ok AFAIK.

Have heard people speak about taking it on motorway and maintaining certain revs/speed.

lurchy666 · Post by **lurchy666** » 29 Nov 2009, 13:56

dunno about citroens but fords you just go for a 10-20 mile drive and the ecu learns all the settings for all the sensors again altho you should take it for a run on dual carrageways and town roads so it can get the whole range of settings , ie flat out and idle and inbetween,

Post by **xantia_v6** » 29 Nov 2009, 14:01

On my Mk1 V6 I have not noticed any difference after battery removal. Maybe this ECU keeps the learned settings in non-volatile memory.

On the 8V 2 litre engine, the idle speed settings all got reset on battery removal. I would not worry about it.

lexi · Post by **lexi** » 29 Nov 2009, 14:21

While we are on subject V6. The autobox sport ratios. When selected, the LED shows chosen selection. when in standard for a while or on starting out in morning the led is out. Is that the normal?

Post by **xantia_v6** » 29 Nov 2009, 14:28

lexi wrote:While we are on subject V6. The autobox sport ratios. When selected, the LED shows chosen selection. when in standard for a while or on starting out in morning the led is out. Is that the normal?

you have confused me now

On the Mk1, there is a light bulb that illuminates the position of the lever (a bit fiddly to change), and an LED in each of the sport and snow buttons.

The Mk2 also has a gear indicator on the dashboard in place of the oil temperature guage, which has LEDs for gear selection and sport and snow modes.

I think you are saying that your light bulb is intermittent. Maybe it is a bit loose?

lexi · Post by **lexi** » 29 Nov 2009, 15:40

Mine is Mk 1. I refer to the rocker switch down by the gearchange. It has two settings? I assumed one was sport (it has an S) Ah! the other setting is Snow? That is pulling away in 2nd or third?......it has little symbol? I refer to that one. when you press that it lights for a while .........but is off when you restart. So I wondered what mode it was then in.........normal? because no led is on now...sport or snow.

I assume the switch on dash is for Hydractive valves. I have no manual with relevant info.

Thanks

Post by **xantia_v6** » 29 Nov 2009, 15:50

Yes, I think you have it now. When not in sport or snow modes, it is in normal mode. It reverts to normal mode when switching on the ignition.

The hydroactive switch is the button with green logo just forward of the height lever. It is illuminated in sports mode, of if the lights are on. You can often only tell which position it is in at night with the lights off.

Stempy · Post by **Stempy** » 29 Nov 2009, 23:34

lexi wrote:If the battery is disconnected on V6 for any length of time how does ecu reprogramme itself. My battery was out but all seems ok AFAIK.

Have heard people speak about taking it on motorway and maintaining certain revs/speed.

I was told by an injection chappy that when you reconnect the battery you should switch on the ignition and then before starting the engine depress the accelerator fully a couple of times so the ecu can map the tps.

Post by **CitroJim** » 30 Nov 2009, 07:07

Stempy wrote: I was told by an injection chappy that when you reconnect the battery you should switch on the ignition and then before starting the engine depress the accelerator fully a couple of times so the ecu can map the tps.

Totally the opposite of what the official instructions say! Turn on ignition, de-immobilise, wait at least five seconds and then start. Do not touch the accelerator at all.

Then use a Lexia to check butterfly position at idle, mid-position and WOT.

My (MK1) ECU does appear to retrain after a battery disconnect.

Stempy · Post by **Stempy** » 30 Nov 2009, 07:48

Well if that's the official Citroen line then that's the one to go for. I guess FI systems vary quite a lot so you can't really go by a general rule of thumb.

The ECU must be constantly 'learning' anyway, allowing for varying fuel octane and component tolerance. Probably not as complex a system as those on modern cars though.

addo · Post by **addo** » 30 Nov 2009, 07:57

Gearbox in mine seems to revert to "Economy Law 1" fairly smartly anyhow - I wonder what one has to drive like, for it to start off differently!

One indicator to look for with the ECU reset, is a raised kerb idle on initial startup. I reckon this is a no-stall choice of the computer when it hasn't fully quantified the response of the IAC.

lexi · Post by **lexi** » 30 Nov 2009, 11:38

Many thanks to all replys.

Post by **CitroJim** » 30 Nov 2009, 12:26

addo wrote:Gearbox in mine seems to revert to "Economy Law 1" fairly smartly anyhow - I wonder what one has to drive like, for it to start off differently!

If the AL4 is like the 4HP20 Adam, it'll only resume using the same law as last time if the gearbox oil is hot (above 60 degrees). If not, it'll start off using the warmup law and then once up to temperature, it'll then decide the best law to use with no reference back to the last operational law used.

addo · Post by **addo** » 30 Nov 2009, 13:08

Interesting; I'll try that in the coming few days. To get gearbox data I have to input the car as a 406 Pug!

lexi · Post by **lexi** » 30 Nov 2009, 21:13

Took it out today for for a first real try after recomissioning and gentle running. A and B roads with big open stretches and twisty bends.

Very very nice. All works as it should. Difficult to actually drive it to the limit on these roads without being silly. Handles as well as wifes Prelude despite being a much bigger car. Obviously smoother and with more comfort thrown in . Impressed

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