E85 conversion

[Expertamateur]

I think I may have mentioned in one of my other postings I am less than impressed with the petrol consumption of my 2006 307CC 2.0i 16v. Someone suggested I might want to try an E85 conversion. I followed a link to a site selling a conversion kit that appears to be a very easy job. Its a box that simply plugs into the injectors. It modifies the timing and duration of the fuel charge without having to mess with the onboard ECU. It is manufactured here in Europe and costs around €250. Given the global fuel price rises caused by the Golden psychpath across the Atlantic, the price of E85 at €.86 vs €2.24 around here interests me.

I have done a lot of research and most of it is inconclusive. Some sources say only cars that openly claim to be "Flexifuel" can use it. Others say a wide range of engines after about 2000 can be converted or reprogrammed successfully. One thing seems to be universally agreed...........although it is a higher octane fuel, the engine will use more of it, partially losing some of the price advantage. I was wondering if anyone here has had experience running an older 307 engine on it.

[mickthemaverick]

A connected comment but not really relevant!! I run both my older cars on E5 because of potential damage to seals etc but it does cost a lot more than E10. I would have thought that by that metric E85 should be much cheaper than E10 so it may be a winner as long as the engine internals can cope!!

[Expertamateur]

All I can work out so far is that the people that sell the conversion kits say that cars built since about 2000 will be OK with ethanol, but since they sell the kits you can take their info with a grain of salt. Like you, I've been paying the extra for E5 to minimise the ethanol content to hopefully save the engine damage. I need to be absolutely certain that using E85 won't lead to disastrous engine failure.

I was looking for input from actual users. Prices here in northern France today are as follows but actual savings will depend on how the miles per gallon of the two fuels actually compare. The sellers do admit the mpg is up to 25% lower with E85.
95 octane E10 is €2.13
98 octane E10 is €2.25
E85 is € 0.86

[xantia_v6]

I looked into this a few years ago while living in France, and came to the conclusion that it is technically possible for such a conversion to work well, as the conversion box is in principle just measuring the length of each injection pulse and multiplying it by a value to compensate for the lower calorific value of E85, with the calculation being corrected by the readings from the O2 sensor. You do need to remember that an injector cannot have a pulse width of more than 100%, so depending on the original tuning of the engine, the E85 system may under-fuel the engine at high load.

At the time I looked at it, I found that to drive to the nearest E85 pump from my home was a 50km round trip, which would not be convenient, and we did not drive enough kilometers in a year to make the conversion viable.

BTW, the year 2000 limit is apparently due to EU law that mandated ethanol-safe fuel lines from the 2000 model year, but most manufacturers were actually compliant earlier.

[Expertamateur]

Your assessment confirms some of what I have found. My nearest source of E85 is about 11km away so would not be a factor, and the town where my most usual shopping is done also has an E85 source. Your mention of connection to the O2 sensor is news. It was not mentioned in the website I visited although they seem quite eager to respond to any questions about the installation. It seemed to stress the simplicity that it is very much a DIY possibility. All the leads have the correct connectors ready installed and the only other thing would be to establish a connection to a live that will remain active while the starter is operating. Not a deal breaker for me. Thankyou for your response.

[xantia_v6]

When I looked, there were a couple of brands of conversion units available, one certainly intercepted the O2 sensor signal, the other I am not sure now. It may also work using the original ECU to do the mixture correction, but I don't think that it would be as efficient, due to the need to adapt to different ratios of E85 when the tank contains a mixture of both fuels.

[Expertamateur]

Fair comment. There is a lot to learn before taking the plunge. I'm not just worrying about wasting €250 for the kit, but if it all goes belly-up and damages the engine I will be unable to deal with the rebuild.