Tesco Momentum 99...am I imagining this

[Horatio]

I havent bought fuel from Tesco since 2002. Clogged everything up, 17 other people at the indy garage had the same problem used the same petrol station.

[richtung]

For those who use Momentum 99 and live near a Costco Fuel station - good news! Costco now do 99 RON Super unleaded (it used to be 97 RON).

A quick search indicates the fuel is supplied by Greenergy who also supply Tesco.

I don't have the latest prices to hand but im confident Costco 99 RON will be cheaper than both Shell and Tesco.

A link to the Costco leaflet talking about their fuels https://srv-file1.gofile.io/download/w1ry3d/785ba8c580bf94bda735aa3b2fbcd1e2/Costco-Fuels.pdf (originally linked from scoobynet)

Hope this helps!

Rich

[Orc]

Always use Tesco 99, runs way better on all the mk5s i have had, Niki even filled with V power whilst i was up there and noticed a massive difference in response. Always V power for me, plus its just around the corner.

[grey golfster]

Generally run on Tesco momentum 99....have little choice as nearest She!l is 20 miles away!

Have to say when I do use Shell I can't tell the difference, either from numbers or seat of pants.

[pudding]

So many misunderstandings about fuel:

Any improvement from filling up with a different fuel is because it's cold.  Cold fuel has a similar affect/benefit as cold air.  It's even more noticeable on a port injected engine which has a return line from the fuel rail.   This is why diesels have fuel coolers and MK5s switched to a return-less fuel rail.

An engine that meters fuel via air mass can't suddenly improve it's mpg from octane rating or fuel brand.  Mpg is directly proportional to the throttle pedal!  If the mpg improves, you are driving the car differently, or there is less wind that day, or the air is a bit denser etc etc.

ECUs do not continuously add ignition advance until it hears pinking, therefore 'tunes itself' to the octane.  ECUs are set up with the MBT at the factory, for the fuel specified on the filler flap (98 in our case).  The ECU can only retard, it cannot 'add' timing on the fly.

Fuel does not 'go off', certainly not within the time frame of a frequently used car.  I've had V power sat in a tank for 11 months whilst working on a project car, and it fired up and ran perfectly on 'stale' fuel.

Any sudden change in behavior from switching fuels is likely down to contamination.   The Engine/ECU really doesn't care what's in the tank, so long as it meets the minimum RON.  It's all pretty much placebo.

I stopped using Momentum 99 back when I had my R32, because it started misfiring pretty much immediately after filling up with it.   Never had that before or since with V power.

What I can tell you about V power is it does seem to contain some nice cleansing additives.  I did 60K miles in an old project car.  Freshly built engine, V power used exclusively.  I stripped it down after 60K at everything in the combustion chambers was spotless     These additives make NGK Iridium plugs turn orange!

[Dan_FR]

So many misunderstandings about fuel:

Any improvement from filling up with a different fuel is because it's cold.  Cold fuel has a similar affect/benefit as cold air.  It's even more noticeable on a port injected engine which has a return line from the fuel rail.   This is why diesels have fuel coolers and MK5s switched to a return-less fuel rail.

An engine that meters fuel via air mass can't suddenly improve it's mpg from octane rating or fuel brand.  Mpg is directly proportional to the throttle pedal!  If the mpg improves, you are driving the car differently, or there is less wind that day, or the air is a bit denser etc etc.

ECUs do not continuously add ignition advance until it hears pinking, therefore 'tunes itself' to the octane.  ECUs are set up with the MBT at the factory, for the fuel specified on the filler flap (98 in our case).  The ECU can only retard, it cannot 'add' timing on the fly.

Fuel does not 'go off', certainly not within the time frame of a frequently used car.  I've had V power sat in a tank for 11 months whilst working on a project car, and it fired up and ran perfectly on 'stale' fuel.

Any sudden change in behavior from switching fuels is likely down to contamination.   The Engine/ECU really doesn't care what's in the tank, so long as it meets the minimum RON.  It's all pretty much placebo.

I stopped using Momentum 99 back when I had my R32, because it started misfiring pretty much immediately after filling up with it.   Never had that before or since with V power.

What I can tell you about V power is it does seem to contain some nice cleansing additives.  I did 60K miles in an old project car.  Freshly built engine, V power used exclusively.  I stripped it down after 60K at everything in the combustion chambers was spotless     These additives make NGK Iridium plugs turn orange!

Not strictly true. Brand is irrelevant but the calorific value of fuel will vary depending on the brand i.e. the fuel & additives used. The higher calorific fuel will produce more energy per combustion stroke resulting in a lower request (via the right foot) for fuel.

One cause of varying calorific content is the ethanol content. Momentum complies with BS EN 7800 which allows for up to 5% ethanol content. Ethanol has a much lower calorific value than petrol. Tesco admit that the Ethanol content varies between 0 and 4.8% depending on the location and supplier. Just one example.

As for ignition advance - It is surprising when logging a standard car just how much advance there is on a standard map, and just how much correction is going on, especially on 95 RON fuel.

[Paradox1]

I dont user V- power any more, mainly due to it being more expensive than the other super fuels sold.
Test is my main for super unleaded.

Although, if it wasnt so far to drive to, id fill up with sainsbury's . My car performed at its best on that stuff

[flashp]

Some interesting replies, some of which went over my head 
However, the most likely conclusion is that my Shell garages (Rowlands Castle, Hampshire and Farlington) don't have a good quality supply of V-Power.
I think I'll continue with Tesco's and see how it goes longer term.

[reflexsilverfox]

i can get momentum near me for £1.17.1 at the minute which is nearly 20p a litre cheaper than V-power by me. I'm sure V-power is better but for the minimal difference i can't see it's worth the extra.

[pudding]

So many misunderstandings about fuel:

Any improvement from filling up with a different fuel is because it's cold.  Cold fuel has a similar affect/benefit as cold air.  It's even more noticeable on a port injected engine which has a return line from the fuel rail.   This is why diesels have fuel coolers and MK5s switched to a return-less fuel rail.

An engine that meters fuel via air mass can't suddenly improve it's mpg from octane rating or fuel brand.  Mpg is directly proportional to the throttle pedal!  If the mpg improves, you are driving the car differently, or there is less wind that day, or the air is a bit denser etc etc.

ECUs do not continuously add ignition advance until it hears pinking, therefore 'tunes itself' to the octane.  ECUs are set up with the MBT at the factory, for the fuel specified on the filler flap (98 in our case).  The ECU can only retard, it cannot 'add' timing on the fly.

Fuel does not 'go off', certainly not within the time frame of a frequently used car.  I've had V power sat in a tank for 11 months whilst working on a project car, and it fired up and ran perfectly on 'stale' fuel.

Any sudden change in behavior from switching fuels is likely down to contamination.   The Engine/ECU really doesn't care what's in the tank, so long as it meets the minimum RON.  It's all pretty much placebo.

I stopped using Momentum 99 back when I had my R32, because it started misfiring pretty much immediately after filling up with it.   Never had that before or since with V power.

What I can tell you about V power is it does seem to contain some nice cleansing additives.  I did 60K miles in an old project car.  Freshly built engine, V power used exclusively.  I stripped it down after 60K at everything in the combustion chambers was spotless     These additives make NGK Iridium plugs turn orange!

Not strictly true. Brand is irrelevant but the calorific value of fuel will vary depending on the brand i.e. the fuel & additives used. The higher calorific fuel will produce more energy per combustion stroke resulting in a lower request (via the right foot) for fuel.

One cause of varying calorific content is the ethanol content. Momentum complies with BS EN 7800 which allows for up to 5% ethanol content. Ethanol has a much lower calorific value than petrol. Tesco admit that the Ethanol content varies between 0 and 4.8% depending on the location and supplier. Just one example.

As for ignition advance - It is surprising when logging a standard car just how much advance there is on a standard map, and just how much correction is going on, especially on 95 RON fuel.

That's a good point and I can see that when comparing diesel to petrol to ethanol, but surely petrol vs petrol is going to have a negligible difference in calorific value? For the ECU to proactively read a difference in calorific value, it would need a fuel content sensor + appropriate compensations.

For one fuel to 'feel' more responsive than another for a given pedal request, and therefore smaller injector duties, it would have to be one hell of a difference in calorific value.  I have yet to notice much of a difference between the usual brands, other than WOT conditions where the better fuels don't cause as much timing pull.

Maybe Tesco's ethanol range of zero to 4.8% percentage could explain the inconsistency some people notice?

Yeah, lots of timing at low loads but as soon as it goes anywhere near boost, down it goes, way down.....even to the point of firing AFTER tdc!  These engines don't need a lot of timing on load as the combustion chambers are good and direct injection negates the need for a ton of timing to some extent, because higher CRs and homogenized burn the fuel/air mix faster. 

[Dan_FR]

That's a good point and I can see that when comparing diesel to petrol to ethanol, but surely petrol vs petrol is going to have a negligible difference in calorific value? For the ECU to proactively read a difference in calorific value, it would need a fuel content sensor + appropriate compensations.

For one fuel to 'feel' more responsive than another for a given pedal request, and therefore smaller injector duties, it would have to be one hell of a difference in calorific value.  I have yet to notice much of a difference between the usual brands, other than WOT conditions where the better fuels don't cause as much timing pull.

Maybe Tesco's ethanol range of zero to 4.8% percentage could explain the inconsistency some people notice?

Yeah, lots of timing at low loads but as soon as it goes anywhere near boost, down it goes, way down.....even to the point of firing AFTER tdc!  These engines don't need a lot of timing on load as the combustion chambers are good and direct injection negates the need for a ton of timing to some extent, because higher CRs and homogenized burn the fuel/air mix faster. 

The point was that our petrol isn't just petrol. It's petrol, mixed with ethanol, benzene and a whole host of other additives and it does vary a lot. The ECU won't see any difference, other than the car will produce more power for the given fuel, meaning less (right foot requesting) is needed. Small changes to mixture need to be compensated for due to the ethanol content affecting lambda reading, but again we're talking a couple of percent which is marginal at best

Going back to the test linked previously as supplied by Momentum, it pretty much sums up that Momentum is better than branded or non branded 95, but that 'other 99' fuels i.e. the unnamed Shell V-Power, is better again

I dunno, I'm far from an expert. I just know that 'fuel' isn't just fuel regardless of brand

[Manny_ED30]

I've used both in my edition 30 and not noticed a real difference driving wise BUT I've been getting a good mpg return recently and this has been since I started filling up from Tesco as its a couple of pence cheaper! Either way, only 99 Ron goes in the tank

[pudding]

That's a good point and I can see that when comparing diesel to petrol to ethanol, but surely petrol vs petrol is going to have a negligible difference in calorific value? For the ECU to proactively read a difference in calorific value, it would need a fuel content sensor + appropriate compensations.

For one fuel to 'feel' more responsive than another for a given pedal request, and therefore smaller injector duties, it would have to be one hell of a difference in calorific value.  I have yet to notice much of a difference between the usual brands, other than WOT conditions where the better fuels don't cause as much timing pull.

Maybe Tesco's ethanol range of zero to 4.8% percentage could explain the inconsistency some people notice?

Yeah, lots of timing at low loads but as soon as it goes anywhere near boost, down it goes, way down.....even to the point of firing AFTER tdc!  These engines don't need a lot of timing on load as the combustion chambers are good and direct injection negates the need for a ton of timing to some extent, because higher CRs and homogenized burn the fuel/air mix faster. 

The point was that our petrol isn't just petrol. It's petrol, mixed with ethanol, benzene and a whole host of other additives and it does vary a lot. The ECU won't see any difference, other than the car will produce more power for the given fuel, meaning less (right foot requesting) is needed. Small changes to mixture need to be compensated for due to the ethanol content affecting lambda reading, but again we're talking a couple of percent which is marginal at best

Going back to the test linked previously as supplied by Momentum, it pretty much sums up that Momentum is better than branded or non branded 95, but that 'other 99' fuels i.e. the unnamed Shell V-Power, is better again

I dunno, I'm far from an expert. I just know that 'fuel' isn't just fuel regardless of brand

Me neither, I just try to understand things from a tuning / electronics point of view and I struggle to get my head around why one brand of 99 would give better economy than a different brand of 99.  Still, it's interesting debate regardless of a factual answer or not!  Your theory could be tested by logging pedal requests on a tank of Tesco, and then again with a tank of V power, all in the interests of science.

The only times I've had trouble with fuel was a misfiring R32 on Momentum, and way back in 2004ish when a batch of supermarket fuel was contaminated with silicone, which killed off 1000s of O2 sensors.

Another reason I use V Power is because I always roll up to an empty pump.   For Tesco I always have to queue for ages because it's cheaper, especially on Friday lunchtimes.  Can't be bothered with that.

[AJP]

When I first bought my Gti I didn't know it needed higher Ron fuel until a few weeks of standard unleaded I switched to v power. After finding out Tesco sold 99 Ron for alot cheaper than v power I've always used Tesco 99.

I drive a stock Gti and have no idea if it will make a significant difference but if I'm putting a better grade of fuel in then it's all good.

Dosnt rtech also say when mapping to have a tank full of v power or Tesco 99 in when getting the car mapped? Must be something in it if that's their requirements

Just noticed this. Worth mentioning (if I've interpreted what you're saying correctly) that it's not just for the mapping session you'll need 99 in the tank. It's from then on: If your car is mapped on 99, run it on 99 at all times.

It wouldn't do any good at all to stick 95 in a car with an R-Tech map!

[shoaybmakda]

@AJP I have no idea - I haven't visited rtech yet!

But yes your right it would make no sense to go back to 95 Ron. I just went on reading posts that a lot of people said you need 99 in your tank when visiting them.

But even still on my stock car I only use 99 Ron now