Xantia V6 broken exhaust (update: and rough low rpm running)

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Mandrake
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

DHallworth wrote:Could it be an adaptive value that the old ECU needs to learn after having sensor changed?

I know on the Range Rover ECU's you clear the existing running config which causes it to run like a bag of spanners for a few miles, you take it for a run of mixed driving and it resets itself. According to the workshop manual, this is supposed to be done when replacing any of the engine sensors such as MAF, Lambda's, TPS, etc.

David.
Hi David,

There's not a lot of detailed technical information on the MP7.0 that I can find, but according to what I've read unlike some ECU's none of the things it learns are retained when the battery is disconnected for at least 10 minutes. (In contrast to the gearbox ECU for example which has an eeprom that copies the auto adaptive tables from ram to eeprom 20 seconds after a key off event)

In other words it goes back to a blank slate with default values every time you take the battery off. When you start to drive it learns from the sensors and populates the long term fuel trim and knock retard tables. I'm not entirely sure whether the knock retard starts off "conservative" and creeps forward to a high octane map over a period of running, (I run 99 octane) or whether it starts off high and knocks it back if it detects a lot of pinging.

My ECU swapping suggest that it starts fully advanced after a reset and pulls the timing back quickly if it detects any pinging, (to adapt for low octane) as 9 times out of 10 a swapped or reset ECU starts off with maximum performance and then may intermittently tail off after some amount of driving.

There is a procedure listed in one of the technical documents "auto-adaption of the (mixture) richness" which says:

* Warm the engine up to over 80 degrees
* Check there are no stored fault codes
* Turn ignition off then on again
* Start engine without pressing accelerator
* Let the engine idle for 5 minutes without pressing the accelerator

It also states that clearing the fault codes will not reset the mixture adaption. (but disconnecting the battery will)

I've tried this procedure before and didn't notice anything in particular - all its doing is giving enough time for the oxygen sensor to warm up so that it can learn the long term fuel trim for a stoichiometric ratio.

Given that battery off means a reset to defaults I've almost always found that the engine runs best immediately after the reset and deteriorates over time, so it doesn't seem to need any special procedure like you mention for the Range Rover.

On Sunday I literally went for a 20 minute drive on your ECU - perfect performance as it had been all week, came home, swapped the ECU's, immediately went out again for another 20 minute drive with the engine still warmed up - perfect performance immediately. (But will it last more than a few days... I don't know yet)

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Chris570
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Chris570 »

The unthinkable has happened!

This thread wasn't on the first page.

I pondered this thread while spamming Jim's and I notice that we're shy of 100 pages.

Not that I would advocate spam of course but...... 100 is a special number and I would like to think that some day (soon) this will get there.

So i wonder, does anyone else have a special number?

if not, do we like kittens or puppies?

Stempy
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Stempy »

My special number is 2946, as I'm allergic to cats I can't say I'm too fond of kittens but puppies are fine as long as they grow to be no bigger than a Labrador.

Hell Razor5543
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Hell Razor5543 »

My Mum used to breed Seal point Siamese (she was the first breeder in Europe to breed 2 European Grand Champions), and the kittens are so cute (pure white when they are born, developing the markings as they get out in the sun). She never let them get snooty or have airs and graces. As a result, they were family pets that happened to be championship winning pedigree cats.

Northern_Mike

Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Northern_Mike »

My special number is 290764 and I prefer kittens to puppies. I would like to own a Norwegian Forest cat at some point.

I also love owls.

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bobins
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by bobins »

We've got a cat called Lulu. I don't like most dogs.
A special number doesn't spring to mind, but if I think of one, I'll post it up here. :-D

addo
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Post by addo »

I'm mostly a cat person, but noticed on Saturday night last, there were a couple of seriously large puppies in the bed with me.

Northern_Mike

Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Northern_Mike »

I have this "issue" every night.

I would, however, also like a "pet" owl. I'd call it Dr. Who.

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addo
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Post by addo »

We really need a "Like" button sometimes. :lol:

Stempy
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Stempy »

Image

Clumbsey
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Clumbsey »

when 100 you get a Card from "The Queen"

spent all day reading this brill

Stempy
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Stempy »

Things must be going rather well as there have been no updates for quite some time. Could it be that the V6 is fixed?

Xantidote
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Xantidote »

Yes, I'd noticed it's gone very quiet. Hello Simon (he shouts)..... anyone there? Maybe he's Xmas shopping? Surely the V6 isn't fixed, or is it? :-D :-D :-D

Stempy
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Stempy »

Seemingly not as it looks like he's gonna have to have the dash out.....

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Mandrake
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

Clumbsey wrote: spent all day reading this brill
Good grief, I wouldn't wish that on my worst enemy :lol:

Did you come away with any conclusions after reading it all in rapid succession ?
Last edited by Mandrake on 19 Dec 2013, 16:38, edited 1 time in total.