Another "What Fuel" Thread

[Matt82]

there isnt a 99-98-97 map. the ecu wont go "hmmm this tastes like half a tank of 99, a quarter tank of 95 and a quarter of 97. lets run the xxx map"

the ecu advances timing for given condtiions, throttle, engine temp, load etc. if detents knock or a misfire etc it will pull the timing for a set time (seconds, it readjusts all the time)

on a WOT run through a gear you can see 2-3* of "correction" at 3-4krpm which then readjusts down to 0.8* by 6krpm

 

[Scania]

there isnt a 99-98-97 map. the ecu wont go "hmmm this tastes like half a tank of 99, a quarter tank of 95 and a quarter of 97. lets run the xxx map"

the ecu advances timing for given condtiions, throttle, engine temp, load etc. if detents knock or a misfire etc it will pull the timing for a set time (seconds, it readjusts all the time)

on a WOT run through a gear you can see 2-3* of "correction" at 3-4krpm which then readjusts down to 0.8* by 6krpm

I'm reading that as it - the car's ecu - effectively maps in real time depending on what fuel it "tastes" at any given moment in the running cycle??

Yes, I conceed your reply made my brain hurt a tad!

 

[Matt82]

pretty much. the software thats loaded defines the limit it will advance to for its given conditions (ie throttle position, engine load, engine temp etc)

so if you have a car thats left the factory and never intended to use more than 95ron, the ignition will only go as far as "X"

then it gets chipped, remapped, new software is on there, ignition gets pushed forward a bit, this time to "Y"

then some idiot like me gets hold of it, plays about with the ECU more and with the help of further logging and testing pushes it to "Z"

------>X
--------------->Y
-----------------------Z

 

[Scania]

Nice one Matt, cheers.

 

[ramirez]

Having had the Legacy GT-B (JDM) for over a year now, I can say that she does respond better to 99 RON both in economy and performance. The marginal increase in fuel efficiency seems to be wiped out by the increased cost of the 99 but she's noticeably smoother in the delivery of the power. She's not faster, just different.

I don't know how to explain that any better, sorry

you shold use SUL in a GT-B anyway as JDM Scooby engines are reknown for crapping up on 95 ron

I use tesco SUL in my XJR as I get marginally better fuel economy in it than 95 ron but I don't think it benefits in any other way.

I use the same in my GTR as that definitely is not meant for 95 ron.

 

[MikeHiow]

On your ST engine? You will need some modifications to run E85

Oh, I'm under no illusions that I could just dump it straight in, but given the opportunity and availability, I'd love to do it - it'll never happen though.

 

[Gornall]

I use tesco SUL in my XJR as I get marginally better fuel economy in it than 95 ron but I don't think it benefits in any other way.
QUOTE]

Enough to off-set the extra cost?

 

[mast3r]

so the extra MPG you gain from SUL. does this work out cheaper then? as it is still 3p PL more than 95 or is it near 5p?

 

[MikeHiow]

My local Tesco is currently 5p more for SUL atm - that's just £2.50 over a 50 litre tank.

220 miles NUL (20MPG)
253 miles SUL (23MPG)

33 miles more which doesn't quite make it even, but leaves SUL about 70p more per tank (mile for mile) in this example, but many would consider that worth it for the other benefits of SUL (Performance, responsiveness, cleaning properties etc.)

 

[Matt82]

in my cars its marginal whether it makes financial sense but with the turbo it way it makes off down the road on SUL (pretty essential with my ecu tweaks) then its worth the money every time

 

[zipp0r]

so the extra MPG you gain from SUL. does this work out cheaper then? as it is still 3p PL more than 95 or is it near 5p?

50L @57.95 or 59.95
£2 extra for 60 extra miles, i could maybe stretch to 100 extra but it wud not be easy.
im not sure but it looks about even with the price per extra mpg, i do not think about the mpg gain so much, i use it for its anti-knock properties.

 

[danza]

My EP3 has done the last 20K + on 95RON which is what the manual recommends. It still goes fast, makes nice sounds and hasn't grenaded its engine due to poverty spec fuel with extra added offal and vagrants.

My company car, a Suzuki Swift Sport, has 97RON+ recommended in the manual and on the filler cap. It gets 99RON from Tesco.

 

[HaMMuS]

I was under the impression that supermarket fuels contain less additives/cleaners/lubricants than Shell/BP etc. So using supermarket fuels over time, you can get buildup of gunk in your injectors and other parts of the engine. Is this accurate?

 

[Steedie]

Put the Shell FuelSave Diesel in last night as I wasn't near a BP and had to fill up. Only put a tenner in so I can get more Ultimate soon but the difference is night and day, car feels so rough compared to when running on Ultimate

And my MPG is 3 less!!!111111one 3 EMM-PEE-GEES!!