General: Experience of ECU remapping and RON rating

[2.4TSE]

Some shared experience, purely out of interest.

I BSR PPCd my owned-from-new 2003 V70 2.4T just before its second birthday in March 2005 when the two year warranty expired (I personally imported from Holland so did not have a dealer-supported third year like I would have done with a UK supplied car). Since then every single tank of fuel in the next 50,000 miles bar the one I am about to describe has been of a minimum 97 RON, usually 98, and even on a few occasions 100 RON (in a backwater town in Czech Republic of all places when my local garage in UK only stocks diesel and 95). I had not therefore had opportunity to feel the importance of super unleaded fuel for my remapped engine other than common sense and believing BSR that it was necessary in order to extract the full potential of the remap.

Filling up in the Black Forest last week however whilst paying more attention to the questions from my kids than studying the pumps I failed to remember that "Super" was in fact "Normal" 95 and that if I wanted 98 I needed "Super Plus" (Germany having Normal as 91 RON that we don't commonly have in the UK). I realised what I had done when about 65 of the 71 litres had gone in...

Was the power delivery inferior?
Not half!

With 36 deg C ambient temperature, four people on board, and the heavily laden boot of a camping holiday, I left the village where I'd filled up and headed for the steep surrounding hills where our journey was to continue. Initially all was well but within twenty miles instead of effortlessly romping out of steep hairpins from 1200 RPM I now needed second gear to gain the same oomph there being a gaping chasm below 1900RPM, and instead of a storming third gear mid range to gallop up the next steep straight and shrug off the load like the car was empty, it now accelerated with the symptoms of a mildly failing boost control solenoid (been there, had that, prior to IPD replacement). Stutter-pull-stutter-pull-stutter-pull up the rev range. Both symptoms were inferior to what I remember from a stock engine on 95 RON whereby it was much less grunty but consistent. On the autobahn later in the day the engine pulled well but without the invisible force that normally sweeps 70mph in fifth gear deep in to three figures in one relentless charge and with a satisfied smile on my face every time I have done it on the five previous round trips between UK and CZ in this car. Although I was presented with an ideal opportunity on the empty new autobahn before Rozvadov, out of deference to the engine and increased reliance on protection mechanisms with prolonged full throttle at high RPM I decided not to see what the maximum speed was.

Having pretty well emptied the tank (I resisted a part fill with 98 RON) and now in Czech Republic I refilled with 65 litres of "V-Power Racing" (as Shell call their 98 RON product here) and found normal service resumed within about thirty miles. No lack of bottom end torque, no stuttering mid range, no flat flat upper range, just a strong engine that gathers all the cavalry in a surge leading up to 1800 RPM and then storms off with the unburstable delivery that I have grown to take for granted.

Time to pay more attention when filling up abroad!

[Gen_Billy]

Having tried out both fuels , the more expensive fuels the 98 super unleaded really works well with an BSR upgrade, you can notice the difference in power,you get better fuel consumption too, however the super unleaded fuel is way more expensive per litre...
When Im driving around town I just stick with 95.

[t5_monkey]

anyone who can't feel the difference between 95 and 98, hasn't got a tuned car.

Run mine on V-power (with a BSR tune) you can definitely feel it.