What type of fuel ?

[gov]

still having a problem with " juddering" but only when when hot - noticed that when cold car performs normally - new leads cured the misfiring on hard acceleration - but after about 4 miles and engine is warmed up it plays up a bit ( juddering and even cutting out at a junction ) then clears itself and runs normally - my neighbour has just bought an Audi 3.5 and had the same symptoms - he bought the car from his brother in law who assured him this had never happened before and then mentioned he always used 99 octane fuel - my neighbour filled up with this higher octane petrol and the problem has disappeared - could this be what is happening with mine ? are our cars supposed to use 99 octane ?

Tony

[John_W]

I’d suspect something is out of whack, but don’t have any suggestions as to what (apart from checking everything!). There’s no harm in trying better fuel to see if the problem goes away.

The problem is that it’s not just octane rating that matters these days, but also ethanol fraction, as the EU has been prescribing ethanol to be added to petrol - something that didn’t happen when the Elan was new.

Have a read of the following posts and threads and make your mind up:
- viewtopic.php?f=38&t=27482&p=353743
- viewtopic.php?f=122&t=26882&p=343511&hilit=E10+ethanol#p343511
- viewtopic.php?f=36&t=26488&hilit=E10+ethanol&start=20

John

[theelanman]

you cant use E10 in the Elan....thats the petrol with more Ethanol in it......
you can use E5........
it should say at the top of the pump or somewhere which of the two it is......
as for the octane rating..........I never put anything less than the 97 in......
hey try it and see what happens.......as its 'better' fuel it certainly wont damage anything

[Rambo]

There is an interesting article here....

https://www.autoexpress.co.uk/fuel/1012 ... ium-petrol

Not sure where he finds 100 octane petrol though

I tend to use the Shell V power (formerly Optimax) or Tesco Momentum where possible (99 RON) in both my cars. Yes it costs more but I feel the engine runs better performance wise and I also get marginal rises in mpg

I also use the diesel equivalent in my van every 1000 miles or so, as suggested in the article

[gov]

Thank you for information - took car down today to have some paint done on the remaining bits where the laquer is beginning to peel - journey of about 4 miles - car never played up at all which seems to indicate it might not be petrol - car is with the paint shop for around a week - when I collect it I will fill it with Tesco superunleaded just to see if it helps - here on the IOW Tesco is the only filling station that has anything other than 95 octane.


Tony

[lotusflasherman]

Years ago the TV programme 5th Gear tested Super Unleaded against Unleaded and found for variable valve timing and turbo engines the increase in power gave better performance and increase in mpg that made it more economic. For 'routine engines' it was a waste of money. As I run an Everest chip I would never use 95 unless I risked running dry... but only part fill and top up with 98 or higher at the first opportunity.

With the issue about E10, 98 or higher is the only choice in my opinion..

[theelanman]

But the info from lotus was that the E10 stuff wasn't compatible with the m100

[theelanman]

We need 5star back.......but without the lead......
Would aviation fuel work?........lol
Fill up with racing fuel at your local track.......lol

[gov]

But the info from lotus was that the E10 stuff wasn't compatible with the m100

Superunleaded from Tesco is the only available enhanced petrol here - not sure if it's E10 - will have to pull up to the pump and see if it says so before filling up

Have to ask Gareth - I thought you had sold your Elan months ago - what happened ?

Tony

[theelanman]

I did.......
I was going to buy it back but the guy I sold it to has not been kind to it........ ........
considering he was supposed to be a friend........he whinged at me after he bought it..........the boot was too small......he banged his elbow on the cabin storage box.......and the steering is too heavy
all of which was my fault...........like I designed the frikkin thing.....anyway
so Im buying another........
just trying to finish my Elite off first..........
then I have a couple of cars in my sights........so an m100 may arrive back in my garage sooner than I think......

[Rambo]

Ex friend

[theelanman]

a bleedin w@nker more like

[gov]

a bleedin w@nker more like