Simon's new Xantia V6 and Leaf blog

[CitroJim]

Simon, good to see you here. I trust all is well on all fronts?

[Mandrake]

Hi All,

A long time since my last update (that's a good thing!) and the car is still running nicely. It starts on the first turn even at -4 degrees (brr) and although I've had trouble with the door rubbers sticking the doors shut in the cold and the tyres are NOT the best for cold weather the car has been otherwise reliable. Waiting for the summer months are:

Trackrod ends and possibly droplinks
Four new tyres
Cam belt
Gearbox oil change (engine oil was done just before the winter)
Coolant change
LHM change and filter clean (should I bother with hydraflush ?)

That's about it really. Touch wood the car has been running nice and reliably.

The brake pad warning light has started flickering on intermittently but I'm pretty sure the pads had plenty of thickness left when me and Richard were looking at the lower balljoint so I'm thinking its probably a misrouted wire chafing ? Far too cold and wet to be doing non-essential jobs outside at the moment and my garage is not surprisingly full to the brim with renovation left overs and garden tools that are waiting for a garden shed to call home.

I came across an interesting article I wanted to share that backs up some observations I have made with both my V6's. Some of you might recall that among the issues of the Silver problem child that a lean mixture is something I battled with for which I could never find a definite cause for. In the end I worked around it by changing the fuel pressure regulator from 3 bars to 3.5 bars which did help a lot, and at higher RPM that engine ran like a bat out of hell even when I sold it, in fact to my disapointment the foot to the floor higher RPM acceleration of this new V6 has never been as good as the old one.... after reading this article, I think bumping the fuel pressure up on the old one may explain it the difference between the two cars...

http://www.groups.tr-register.co.uk/wes ... pdate.html

In short, Ethanol is to blame for older petrol engines running too lean! This is not something I had considered before even though I was aware that ethanol was added to most petrol today. Here are some quotes from the article:

Drivability Issues

The ideal fuel/air ratio for a petrol engine (Stoichiometric Air/Fuel Ratio) is between 14.5 & 14.7 to 1. That is 14.7 parts air to 1 part fuel by volume. For pure Ethanol this ratio is between 8.9 & 9 to 1. (9 parts air to 1 part fuel).

This can partly be explained because Ethanol contains 35% Oxygen by weight and therefore will naturally ‘lean-off’ the fuel/air mixture.

Even at only 5% mixture, Ethanol will alter the correct fuel/air ratio and lead to unadjusted engines running weak.

To further add to the problem, vaporisation can lead to incorrect fuel metering and a further ‘leaning’ effect (Enleanment).

Even modern engines using electronic fuel injection systems can be susceptible to this phenomenon. Most modern vehicles use a ‘closed loop’ system to maintain and monitor perfect fuel/air ratio (Lambda 1). This is achieved by the use of an Oxygen (or Lambda) sensor in the exhaust. This is active under idle and light cruise conditions, however under heavier load conditions (WOT ‘wide open throttle’) the system reverts to open loop and relies on the map in the engine ECU. It is unlikely that under these conditions even a modern engine will be able to compensate for the necessary change in fuel/air ratio required when using a fuel other than 100% petrol. Any pinking or knocking caused by a lean mixture may be detected by a knock sensor (if fitted) and lead to reduced engine power and possibly illuminate the M.I.L. (Malfunction indicator lamp) depending on the sophistication of the engine management system. Some manufacturers already produce vehicles that can run on fuel with as much as 85% Ethanol mixture (E85) proving that Ethanol is suitable as a fuel for internal combustion engines provided that it is designed with this fuel in mind but it is unlikely that carburettored vehicles or those fitted with mechanical or early electronic fuel injection will be able to make sufficient adjustment to the mixture strength while running on E10 (which will be here in 2013).

Ethanol has a higher volatility than petrol and therefore is vaporises more readily. This can lead to ‘vapour lock’ in components such as carburettors and fuel pumps etc, particularly if allowed to heat soak. This means that a hot engine that is switched off will heat soak the fuel (which it does anyway) and cause starting problems if the engine is restarted whist still hot. Some vehicles may suffer from vapour lock whilst running, especially on hot days, leading to loss of power and cutting out.

So basically an old petrol injection system that is not specifically designed for Ethanol blends, which includes the fairly primitive by today's standards Bosch MP 7.0 ECU on the ES9J4, will run leaner than it should in open loop mode on Ethanol enriched fuels and get progressively leaner the higher the concentration of Ethanol.

In closed loop mode - when idling, cruising with a light throttle, or passing an emissions test, (!) the oxygen sensor will allow the ECU to compensate for the change in fuel and bring the mixture back to what it should be, however open loop mode will be lean. This means flat spots and hesitation, and reduced power when accelerating hard.

When this article was written (before 2013) and when I had my first V6 the UK was still using E5, but by now we are using E10 so the situation will have gotten even worse.

Also not all fuels have had Ethanol added. Apparently all standard octane (95) fuels in the UK have added Ethanol and are probably E10 by now in 2016, however some of the high octane fuels do not have added Ethanol in some parts of the UK.

So it's quite possible that the performance difference I notice between different fuels is not just Octane rating but the Ethanol percentage, with lower Ethanol fuels performing better in the old engine due to the mixture not being as lean as a higher Ethanol fuel...

I normally use Shell V-Power but as the station is some distance away from where we live now and a new Esso opened up nearby I thought I'd give Esso's Synergy Supreme (97 octane) a try - and I was not impressed. It seemed OK at first but after a while I was really noticing the card did not seem happy, being quite noticeable sluggish. On the next fill I thought I would try Tesco's Momentum (99 octane) and within just a few miles it was back to its zippy self - as good if not better than the Shell V-Power. I have never tried the Tesco Momentum before but after this good experience and considering that it's cheaper than standard octane from most other suppliers I'll give it another try.

So what to do about the problem of E10 ? If the ECU maps could be reprogrammed to richen the open loop mixtures by the correct amount the card would run nearly as well on E10 as it would have on 100% petrol, however remapping is not a viable option on an ES9J4.

The other solution is to increase the fuel pressure, as I did on the old V6 by changing the fuel pressure regulator. It's a pretty standard Bosch vacuum operated fuel pressure regulator used in a lot of different cars, so I'm sure a 3.5 bar Bosch version will be available. The 3.5 bar regulator I fitted to the old V6 was a cheap after market one (about £30) which had some internal leakage so I wasn't very happy with that, so I would definitely be using an OEM Bosch one this time, even though they're around the £90 mark.

In closed loop mode the oxygen sensor will allow the ECU to compensate so it will still run at the correct mixture there and pass the emissions test, however the higher fuel pressure means that the open loop mixture will be proportionally richer, compensating for the leaning effect of the Ethanol. The fuel delivered increases by the square root of the pressure, so going from 3.0 to 3.5 bars is a ratio of 1.1666, take the square root is 1.08, so 3.5 bars will make the open loop mixture about 8% richer.

Another benefit from increasing the fuel pressure a bit is that chances of vapour lock when hot are reduced, as the higher pressures increase the boiling point of the fuel, so this would partly counteract the tendency of E10 to vapour lock.

So if you have an ES9J4 and want to squeeze the last drops of performance out of it, and taking into consideration that most fuels now days have Ethanol in them that weren't there when the engine was originally designed, consider fitting a 3.5 bar pressure regulator!

[Mandrake]

Actually a bosch FPR might not be as expensive as I thought. I think this might be the right one at £68: (would need to double check)

http://atspeedracing.co.uk/products/ind ... 40c746622f

They also have a 4.0 bar one but I think that is going a bit far...

[Hell Razor5543]

Useful info (to those who have old petrol engines). However, with reference to Hydraflush, Citroen recommend an LHM change every 36,000 miles and a Hydraflush every third change (so the first would be due around 110,000 miles), and you are only 2/3 of the way there.

[CitroJim]

Very interesting read about the Ethanol issues Simon. Thanks for posting that. It explains a lot.

[Mandrake]

Hi Jim,

All is well here (in reply to your earlier message that I missed) just not a lot of time to keep up with the forum and nothing to report really!

Yes the ethanol issue is very interesting - the old V6 ran quite lean and I suspect it had other issues contributing to that, however when I have monitored the new V6's oxygen sensor on the scope, whilst it looks OK most of the time there are times (particularly trying to pickup in 2nd gear after slowing down) where I can see that the mixture is leaner than it should be under a wide throttle, and that corresponds with me observing that the performance is not quite what it should be.

However I have not been able to find anything wrong that might cause this - fuel pressure, fuel pump etc are all within tolerance, I can't find any air leaks, the sensors are all good, (replacing the air temperature sensor did help a bit) based on the very low emissions the fuel injectors must be well balanced, etc..

The increase in Ethanol from 0% to 5% to 10% over the last 10 years or so in a car that was designed before Ethanol was introduced explains how an engine that has nothing wrong with it can now be running too lean and not performing as well as it once would have done on pure petrol.

It could also explain why some of the premium grade fuels could cause an engine that doesn't really need high octane to run better - some of them have had lower Ethanol content than the standard 95 octane, but from what I have read this varies in different parts of the country where the premium fuels in some areas do have Ethanol added and in other areas not! (Or a lower percentage) In the ES9J4 you would have both the effects from Octane (as it does benefit from going above 95) and reduction in Ethanol, but if you fill up in a part of the UK that does add Ethanol to premium fuels you would not notice as much difference!

Also interesting to note that because of the lower energy density of Ethanol vs Petrol, and the fact that an unmodified engine will run leaner which may lead to the knock sensor retarding the timing to prevent knocking, you actually get a significant reduction in MPG compared to what you would have got on 100% petrol.

A bit of a dirty little secret that the government imposed Ethanol in petrol can lead to engines not performing as well and getting lower MPG!

[Stickyfinger]

Great stuff here guys....thanks

[CitroJim]

A bit of a dirty little secret that the government imposed Ethanol in petrol can lead to engines not performing as well and getting lower MPG!

Indeed and no doubt we can expect the level of Ethanol to rise in the next few years too...

That and the corrosive aspects of Ethanol are likely to see off a lot more older cars potentially...

[lexi]

So why are they trying to get rid of all this bloody effinall? Can't they put it into McDonalds as a bulking agent?

I was running the 62 Land Rover 2.25 petrol. Designed for leaded fuel. It was well known that this engine did not run just as well on unleaded, apart from the valve recession issues. Add Effinall to the mix and the old Solex had to be tweaked along with IGN timing to suit. I ran the super unleaded fuel with lead replacement fluid. It ran ok on that, once set up by much trial and error.
I honestly think I was captivated by the Moon, running that thing for 4years

[CitroJim]

There's some ruling I believe Lexi, that all fuels must now have a certain percentage of biofuel in it... Diesel has a percentage of biodiesel in it..

[xantia_v6]

A bit of a dirty little secret that the government imposed Ethanol in petrol can lead to engines not performing as well and getting lower MPG!

Indeed and no doubt we can expect the level of Ethanol to rise in the next few years too...

That and the corrosive aspects of Ethanol are likely to see off a lot more older cars potentially...

In France, a few years ago the government sponsored a scheme to introduce E85 (85% Ethanol) into the market. It was said that all cars produced in the EU after 2000 should have fuel systems that would not be harmed by this level of ethanol, but most would need modification to the engine management system.

You can buy tuning boxes to adapt most common engines to run seamlessly on any fuel with 0-85% Ethanol (to cope with refilling partially full tanks). I did look to see that there is a box for the ES9.

As far as I can tell, they monitor the RPM, temperature, lambda and knock sensors and stretch the injection pulses as required.

The E85 scheme has however been a total failure, with no expansion beyond the initial 85 (odd) pumps across France, because no one wants to modify their car and the savings are hard to quantify (because Ethanol increases fuel consumption). The nearest E85 pump to our place in France in 40km away.

[Mandrake]

There's some ruling I believe Lexi, that all fuels must now have a certain percentage of biofuel in it... Diesel has a percentage of biodiesel in it..

That's kind of correct - the ruling actually is that a certain percentage of the total fuels sold has to have biofuel added to it, but there are no stipulations (or weren't) on which fuels. And the required percentage goes up each year.

So initially only Diesel was affected, as small quantities of bio-diesel are tolerated well by most diesel engines. After a while they had to start adding Ethanol to Petrol as well to meet their imposed "Quota", but they only added it to the mass market lower Octane petrol and did not add it to the premium grades, however that is now starting to change too.

It's very hard to find up to date concrete information on the Ethanol content of different brands of fuel in the UK - most of the resources I've found are a few years out of date now which means there will likely be more fuels with Ethanol than a few years ago to meet the steadily rising quota...

The interesting thing is that it's generally accepted from what I've read that E10 is the highest you can go without engine ECU tuning/modification. With the right ECU design much higher percentages up to 85% can be accommodated - but those ECU's are specifically designed to have a learning process to figure out what blend of fuel they have through trial and error monitoring the oxygen sensor feedback in the first X miles after a fill up.

(They monitor the fuel cap being opened and the before and after fuel tank level to estimate how much fuel was added, thus the maximum possible change in blend that the learning process will accept as feasible)

[Stickyfinger]

List of ACEA member company petrol vehicles compatible with E10 petrol (i.e. EN 228 with the current volatility limits specified in EN228: 2008)
Important note applicable for the complete list hereunder:
The European Fuel Quality Directive
(1)
introduces a new market petrol across the European Union from 1st
January 2011 that may contain up to 10% (by volume) ethanol (E10).
For vehicles equipped with a spark-ignition (petrol) engine introduced into the EU market, this list indicates their compatibility with E10 petrol which complies also with the EN 228: 2008
(2)
volatility limits. Other information:
The European Fuel Quality Directive
(1)
requires that member states of the European Union must ensure that sufficient volumes of today’s petrol are available for vehicles that are not compatible with
the use of E10 petrol. Owners of the vehicles indicated in this list that are not cleared for the use of E10 should therefore continue to have EU-wide access to today’s petrol (EN228: 2008(2)) that may contain up to 5% (by volume) ethanol.
In addition, it is a general recommendation that fuels containing metallic additives should not be used.
Additional note on petrol octane:
It is important to note that the compatibility of vehicle with petrol depends both on the petrol octane rating and its ethanol content. The vehicle’s octane requirement must be met and the ethanol content of the petrol may not exceed the compatibility limit.
In case of doubt, drivers are advised to contact their dealer.
Update history: 9th March 2011 updated with additional information on Skoda cars
14th
March 2011 updated with additional information on Audi cars. 29th July 2011
updated with additional information on GM Cadillac, Corvette and Hummer cars
12th July 2012 updated with additional information on GM Chevrolet cars
(1)
Directive 2009/30/EC of the European Parliament and of the Council of 23 April 2009 amending Directive 98/70/EC as regards the specification of petrol, diesel and gas-oil and introducing a mechanism to monitor and reduce greenhouse gas emissions and amending Council Directive 1999/32/EC as regards the
specification of fuel used by inland waterway vessels and repealing Directive 3/12/EEC, Official Journal of the European Union L140, 5.6.2009, p.88.
(2)
European Standard EN228: 2008 – Automotive Fuels – Unleaded Petrol – Requirements and Test Methods. 2
BMW group:
BMW:
All petrol engine BMW models are cleared for the use of E10 petrol regardless of their year of manufacture but the minimum octane required should be observed according to the owner’s manual.
MINI:
E10 is cleared for use in all MINI models with petrol engine after the re-launch of the MINI brand in the year 2000.
Rolls Royce:
E10 is cleared for use in all Rolls Royce models starting with model year 2003, the launch of the Phantom model.
Daimler group:
Mercedes-Benz:
E10 petrol is cleared for use in the vast majority of all Mercedes Benz vehicles with petrol engines, except: first generation direct injection C200 CGI (W203), CLK 200 CGI series (C209) of the years 2002 –
2005; models not equipped with three-way catalysts or produced with a carburetor. These are mainly vehicles older than 25 years.
Smart:
E10 petrol is cleared for use in all petrol engine Smart vehicles.
Maybach:
E10 petrol is cleared for use in all Maybach vehicles.
Fiat group:
Alfa Romeo:
E10 petrol is cleared for use in the following Alfa Romeo models with petrol engines:
MiTo 159: 1.8 16V, 1.8 TBi 16V, 3.2 JTS V6
Brera: 1.8 TBi 16V, 3.2 JTS V6
Spider: 1.8 TBi 16V, 3.2 JTS V6
8C: 4.7 32V
Fiat:
E10 petrol is cleared for all Fiat vehicles of Euro 3 emission levels or newer, starting from model year 2000, except the following vehicles:

Barchetta: 1.8 16V.
Bravo/Brava (182): 1.6 16V.
Doblò: 1.6 16V.
Marea: 1.6 16V, 2.0 16V.
Multipla: 1.6 16V.
Palio: 1.6 16V.
Punto (188): 1.8 16V.
Stilo: 1.6 16V (1.596 cm3), 1.8 16V, 2.4 20V.
Lancia:
E10 petrol is cleared for use in all Lancia vehicles of Euro 3 emission level starting from model year 2000, excluding the following vehicles:
Lybra: 1.6 16V, 1.8 16V, 2.0 20V
Thesis: 2.0 Turbo 20V, 2.4 20V, 3.0 V6 24V, 3.2 V6 24V
Ford:
E10 is cleared for use in all petrol driven Ford models manufactured in Europe since 1992 excluding:
Ford Mondeo SCI CD 132 until 2006.
Jaguar - Land Rover:
Jaguar:
E10 petrol is cleared for use in all Jaguar vehicles with petrol engines starting from model year 1992.
Land Rover:
E10 petrol is cleared for use in all Land Rover vehic
les with petrol engines starting from model year 1996.
General Motors: Opel-Vauxhall:
Opel-Vauxhall:
E10 petrol is cleared for use in all Opel-Vauxhall vehicles with petrol engines, excluding:
Models with the 2.2 litre direct injection petrol engine, motor code: Z22YH (Vectra, Signum, Zafira).
Cadillac:
The following Cadillac models equipped with a petrol engine and regulated with catalytic converter and lambda probe can be used with E10 petrol:
Cadillac BLS.
Cadillac CTS.
Cadillac CTS-V.
Cadillac Eldorado.
Cadillac Seville STS and SLS.
Cadillac SRX.
Cadillac STS. 4
Cadillac STS-V.
Cadillac XLR.
Cadillac XLR-V.
Cadillac Escalade Hybrid.
If in doubt please contact the Cadillac Customer Assistance Centre, email cadillac.europe@gm.com international free phone 00800 8680 8800*
* calls from mobile networks may be charged fees. Please consult your mobile phone provider.
Chevrolet:
All Chevrolet vehicles produced from the model year 2006 with a Euro 4 emissions compliant engine can be run with E10 petrol:
Aveo / Kalos – 2005 onwards.
Cruze / Orlando – all.
Epica – all.
Matiz – 2006 onwards.
Nubira / Lacetti – 2006 onwards.
Tacuma / Rezzo – 2006 onwards.
Spark – all.
This information applies to vehicles in original condition. The suitability of E10 petrol may be affected, particularly in older Chevrolet cars, through the use of non-original Chevrolet parts or through conversions.
If fuel additives are used, please observe the instructions of the additive manufacturer.
Corvette:The following Corvette models equipped with a petrol engine and regulated with catalytic converter and lambda probe can be used with E10 petrol:
Corvette C4.
Corvette C5.
Corvette C6.
Corvette Z06.
Corvette Grand Sport.
Corvette ZR1.
If in doubt please contact the Corvette Customer Assistance Centre, email
corvette.europe@gm.com, international free phone 00800 8680 8800*
* calls from mobile networks may be charged fees. Please consult your mobile phone provider.
Hummer:The following Hummer models equipped with a petrol engine and regulated with catalytic converter and lambda probe can be used with E10 petrol:
Porsche:
E10 petrol is cleared for use in all Porsche vehicl
es with petrol engines since the 1997 model year
(Boxster) and the 1998 model year (Carrera).
PSA Peugeot Citroën:
All Peugeot and Citroën cars with petrol engines are E10 (EN228) compatible since 1st January 2000.
Renault group:
Dacia:
E10 is cleared for use in all petrol driven Dacia vehicles.
Renault:
E10 petrol is cleared for use in all Renault petrol vehicles marketed since 1st
January 1997, with the exception of the following models:
RENAULT 19;
Megane 1 with 2,0 l F5R 700 direct injection petrol engine;
Megane 1 with 2,0 l F5R 740 direct injection petrol engine;
Laguna 2 with 2,0 l F5R 782 direct injection petrol engine,
and the following models marketed between 1
st
January 2000 and 31st December 2002:
Laguna 2 with 2,0 l F4R 764 Turbo engine;
Laguna 2 with 2,0 l F4R 765 Turbo engine;
Espace 4 with 2,0 l F4R 790 Turbo engine;
Espace 4 with 2,0 l F4R 794 Turbo engine;
Velsatis with 2,0 l F4R 762 Turbo engine;
Velsatis with 2,0 l F4R 763 Turbo engine;
Avantime with 2,0 l F4R 760 Turbo engine;
Avantime with 2,0 l F4R 761 Turbo engine.
Toyota Motors group:
Toyota:6
E10 petrol is cleared for use in all Toyota European petrol models made from January 1998, excluding:
Avensis 2.0 L with engine 1AZ-FSE made between July 2000 and October 2008.
Avensis 2.4 L with engine 2AZ-FSE made between June 2003 and October 2008.
Lexus:
E10 petrol is cleared for use in all Lexus European petrol models made from January 1998, excluding:
IS250 2.5 L V6 with engine 4GR-FSE made between August 2005 and September 2007.
GS300 3.0 L V6 with engine 3GR-FSE made between January 2005 and September 2007.
LS460 4.6 L V8 with engine 1UR-FSE made between August 2006 and September 2007.
Volkswagen group:
Audi:
E10 petrol is cleared for use in all Audi petrol driven vehicles, excluding the following vehicles:
First generation direct injection engines:
Audi A2 1.6 FSI, model years 2003-2005
Audi A3 1.6 FSI, model year 2004
Audi A3 2.0 FSI, model year 2004
Audi A4 2.0 FSI, model years 2003-2004
Audi A4 Saloon petrol engine models with OEM parking heater, of model years 2001-2008. E10 is not
suitable for use during the heating season in countries with colder climates.
Audi A4 Avant petrol engine models with OEM parking heater of model years 2002-2008. E10 is not
suitable for use during the heating season in countries with colder climates.
Seat:
E10 petrol is cleared for use in the following Seat models with petrol engines:
Ibiza, starting from model year 2002.
Cordoba, starting from model 2003.
Leon, starting from model year 1999.
Toledo, starting from model year 1999, excluding the 110 kW 2.0 FSI BLR engine manufactured up to June 2004.
Altea, XL, Freetrack starting from model year 2004, excluding the 110 kW 2.0 FSI BLR engine manufactured up to June 2004.
Alhambra, starting from model year 2001.
Ibiza, starting from model year 2008 (Ibiza V).
All Exeo and Exeo ST models, starting from model year 2009.
Škoda:
E10 petrol is cleared for use in all following Škoda vehicles with petrol engines with the following exception: 7
Felicia 1.3l OHV (40kw and 50kW) engines used in Felicia models in the production years 1994 to 2001 and before. A retro-fit option exists for these engines to make them compatible with the use of E10 petrol – owners are advised to consult their dealer.
Volkswagen:
With few exceptions, E10 is cleared for use in all Volkswagen vehicles with petrol engines. The exceptions are the following models with the first generation of FSI engines:
Lupo 1,4 (77 kW) made from August 2000 to November 2003 (model year 2001 - 2004);
Polo 1,4 FSI (63 kW) made from February 2002 to June 2006 (model year 2002 - 2006);
Golf IV 1,6 FSI (81 kW) made from November 2001 to May 2004 (model year 2002 - 2004);
Golf IV Variant 1,6 FSI (81 kW) made from October 2001 to October 2006 (model year 2002 -
2006);
Bora 1,6 FSI (81 kW) made from October 2001 to September 2005 (model year 2002 - 2005);
Bora Variant 1,6 FSI (81 kW) made from October 2001 to September 2005 (model year 2002 - 2005);
Golf V 1,4 FSI (66 kW) made from November
2003 to November 2004 (model year 2004 - 2005);
Golf V 1,6 FSI (85 kW) made from August 2003 to May 2004 (model year 2004);
Golf V 2,0 FSI (110 kW) made from January 2004 to May 2004 (model year 2004);
Touran 1,6 FSI (85 kW) made from November 2002 to May 2004 (model year 2003 - 2004);
Touran 2,0 FSI (110 kW) made from October 2003 to May 2004 (model year 2004).
Volvo cars:
E10 petrol is cleared for use in all Volvo cars with petrol engines introduced to the market since 1976 based upon servicing and other conditions according to the equipment and material with which the vehicle was originally equipped.
E10 petrol is not cleared for a limited number of S/V40 models with petrol engines produced in the mid-1990s with engine type 1.8 GDI.
8
Not ACEA members:
Saab:
All Saab vehicles with petrol engines are cleared for use with E10 petrol.
Owners of vehicles produced up to the mid-1980s should consult their dealer.

[xantia_v6]

List of ACEA member company petrol vehicles compatible with E10 petrol ...
PSA Peugeot Citroën:
All Peugeot and Citroën cars with petrol engines are E10 (EN228) compatible since 1st January 2000.

I don't know if the above is pedantically correct, but PSA were still producing cars with the ES9 engine at that time, and there was no obvious upgrade to the ECU, so do we infer that all ES9 engines should be compatible?

[Mandrake]

List of ACEA member company petrol vehicles compatible with E10 petrol ...
PSA Peugeot Citroën:
All Peugeot and Citroën cars with petrol engines are E10 (EN228) compatible since 1st January 2000.

I don't know if the above is pedantically correct, but PSA were still producing cars with the ES9 engine at that time, and there was no obvious upgrade to the ECU, so do we infer that all ES9 engines should be compatible?

Depends how you define compatible I suppose...

Compatible, yes in so far as the engine will still run "acceptably" and without suffering damage or accelerated wear (that we know of) or setting the engine malfunction light. After all we've been running our Xantia V6's on E5 or E10 for the most part over the last few years, especially those running them on Standard Unleaded and nobody has noticed any major problems.

However compatible doesn't necessarily infer "runs with no loss of performance compared to 0% Ethanol". Given that the V6 has a lot of "spare" horsepower to begin with something like a 10% loss in performance (guessing at the figure) would not necessarily be obvious, especially when the car is approaching 20 years old and a small dip in performance could be explained away from other factors. Making a direct comparison of how the car used to run many years ago on 0% Ethanol is also very difficult if such fuel is no longer readily available, and/or if you didn't own the same car back at the time. (For example I have never driven a Xantia V6 pre-Ethanol introduction)

From what I've read E10 is the highest percentage considered to be acceptably compatible with unmodified ECU's. In the US various percentages including blends ranging from E15 to E85 are also available for so called "flex fuel" cars whose ECU's are programmed to learn the blend of the fuel. On cars that are not flex fuel in the US the fuel flap specifically warns the owner not to use any blends from E15 or above in the car. Blends over 15% on modern ECU's that are not Ethanol aware are likely to set fault codes due to the ECU detecting an unexplained lean condition that it can't account for - the mixture being too lean by about 10-15% is typically enough to set fault codes and/or engine malfunction light.

The problem with flex fuel designs is that the only way the ECU can learn what the fuel blend is is by empirically monitoring the oxygen sensor feedback under known conditions and measuring how much it has to increase the injection time to get a stoichiometric mixture. The only directly measurable symptom it has to go on is a lean mixture. If the mixture needs correcting for being too lean it knows the Ethanol content has gone up, if it needs correcting for being too rich it knows it has gone down, and it would need to use that information to change the open loop fuel mappings as well. (Which many conventional ECU's including the MP7.0 don't do as far as I know - they only adapt in closed loop mode)

However if the mixture measuring too lean is the only thing it has to go by it then can't easily tell apart a lean reading caused by ethanol from a lean reading caused by an actual running fault such as low fuel pressure. Hence the additional inputs from the fuel gauge and petrol flap switch to monitor when a fillup is done - if the mixture starts running consistently lean without filling up it knows there is a fault rather than it having to adapt to a change in fuel.

Sometimes this learning process can become confused - there was a good ScannerDanner video on Youtube showing a case study of this some months ago where the ECU was setting a fault code and lighting the fault light because it was confused about the Ethanol content of the fuel and had to be reset to force a "relearn" of the current blend in the tank.