ECU / fuel type question 1.8 petrol

[Bob1983]

After a consistent diet of supermarket standard unleaded since I got the car in 2016 (6 years straight and possibly even longer if the previous owner was doing the same) I decided to try a bottle of redex fuel system cleaner and I've been blown away by the results. The system must have been seriously gunked up as I'm now seeing an extra 4-6 mpg (approx range going up to 550miles from around 475 before the treatment) and the power delivery is much more smooth and responsive, the car pulls harder lower down. A flat spot at 4000rpm has gone away and the car now pulls right through it without a hitch. So having seen the benefit first hand of fuel additives, I'm now experimenting with using Shell V Power, if for no other reason than for better additives to preserve the engine internals long term. Considering staying on it for the foreseeable future.

I've seen quite a few people say that any performance/economy benefits would not be seen/felt until a few tanks of super unleaded have been run through the car in order that the ECU can adapt to the higher RON. And I've also seen people saying that some car's ECUs will only retard timing for lower grade fuels (ie 91 RON) but not necessarily advance it for higher grades without also getting the car remapped. The owners manual recommends 95 Ron but says 91 or 98 are possible for my model.

My testing after a fill of shell v power unleaded today has initially seen slightly worse mpg around about 2mpg less than standard unleaded after redex treatment (although the extra weight of a full tank could be a factor here). Tested from cruising at 65mph on dual carriageway before and after filling with the v power. So the tank was nearly empty testing on the standard unleaded (average 40mpg) and full when testing on v power (average 38mpg).

So this leads to my question:

Does the Insignia's ECU/knock sensor setup have the ability to retard/advance ignition timing dependent on the fuel type in use? I have been searching online and haven't found a definitive answer. I have a 2011 1.8L VVT SRI petrol. And furthermore, how long would the ECU need to adapt?

Any advice would be much appreciated!

[lizzard-t]

A knock sensor is there to hear pre ignition within the cylinder or in the old days "pinking " not complete combustion.
and thus will advance and retard the timing to achieve full and complete combustion.
And it is a on-going monitoring system , so is constantly changing.
The knock sensor will tell the ECU to adapt for different types of fuel .
But also you have to remember the MAP sensor will record the mass of dense air entering the combustion process, and if the air is thinner ( ie hotter days) atmospheric pressure is at 1013 1020 bars at sea level
It will try to compensate for the thinner / warmer air by adjusting the amount of fuel , and the point at which the spark plug ignites , and the valve timing ,via the VVT SYSTEM.
redex will clean a possible dirty injector, hence a better ratio of fuel to air , giving you a cleaner combustion process hence a bit more power , and possible a bit better MPG To boot as the amount of fuel being used is being used more economically ( more bang fir your buck .)
wether you get anything better by using V power or alike is an open question.
as it depends alot on the state of the plugs , cleanliness of the MAP ,how much the ECU will adapt to the fuel and what sort of returns you want ,it is a heavy car with a low powered engine at the end of the day.

[Bob1983]

A knock sensor is there to hear pre ignition within the cylinder or in the old days "pinking " not complete combustion.
and thus will advance and retard the timing to achieve full and complete combustion.
And it is a on-going monitoring system , so is constantly changing.
The knock sensor will tell the ECU to adapt for different types of fuel .
But also you have to remember the MAP sensor will record the mass of dense air entering the combustion process, and if the air is thinner ( ie hotter days) atmospheric pressure is at 1013 1020 bars at sea level
It will try to compensate for the thinner / warmer air by adjusting the amount of fuel , and the point at which the spark plug ignites , and the valve timing ,via the VVT SYSTEM.
redex will clean a possible dirty injector, hence a better ratio of fuel to air , giving you a cleaner combustion process hence a bit more power , and possible a bit better MPG To boot as the amount of fuel being used is being used more economically ( more bang fir your buck .)
wether you get anything better by using V power or alike is an open question.
as it depends alot on the state of the plugs , cleanliness of the MAP ,how much the ECU will adapt to the fuel and what sort of returns you want ,it is a heavy car with a low powered engine at the end of the day.

Thanks that's some helpful info. Yeah the car is quite a heavy lump for a 1.8 and to begin with I put the sluggishness down to that and revved it hard when I needed to get it going!

It seems that the recent gains I've had are down to the redex cleaning the injectors which might have had a partial block, which would also explain the 4000rpm flat spot maybe? The car now pulls hard and smooth beyond 4000 in second gear. But it seems I haven't been enjoying the car to its full potential for a long time. Kind of a bummer thinking about all the fuel economy I've lost out on over the last 6 years! Another 50+ miles to a tank would add up to quite a lot in the long term.

I'll carry on with v power for a few fills and monitor things as I go. If others are correct I may need to run a couple tanks full through to start seeing the full effect? (if any), if true it should be apparent in a few weeks time and I'll report back my findings.

But in any case I can always go back to standard E10 and treat the car to a shot of redex here and there to keep the system clear since I've already had great results doing that. Any further gains from using v power would just be a bonus as I see it.

[Bob1983]

Not sure if anyone's interested but..

Just got back from another test run and the car seems to be adjusting positively to the shell v power. As I said in my previous post, the car was fairing slightly worse on consumption after the initial v power fill, giving me less mpg than on standard unleaded (after redex fuel system clear out a couple weeks prior).

Here are my findings so far on the same long stretch of dual carriageway between roundabouts, resetting average mpg coming off the roundabout and recording the finishing average when coming to a stop at the next roundabout. Cruise control at 65mph. Consideration for weight of fuel tank. Very similar outside conditions:

Sainsbury standard unleaded after redex treatment at full, but tank nearing empty at test: 39-40mpg Avg

Shell V Power unleaded full tank:
37-38mpg Avg

Shell V power unleaded 3/4 tank remaining:
41-42mpg Avg

The consumption on shell v power seems to be gradually on the up after the initial slump with only a small difference on weight of fuel tank. So if I'm not mistaken it could well be that the ECU has responded and adjusted the timing to suit the 99 RON, with a small gain inside only half a tank. I will be curious to see if this rises anymore after another tank given that upon filling with v power for the first time, there was still some standard unleaded in the tank that would have diluted the mix. So a more concentrated mix of v power on the next fill up may yield even better results. I'll follow up with my findings!

[Bob1983]

Went for another run today with more good results on Shell V Power although slightly skewed due to the windy conditions. Same long stretch of road on duel carriageway between 2 junctions. Resetting average mpg once off the roundabout at cruise control 65mph and recording final average on slow down to the 2nd junction.

Shell V Power unleaded less than half tank full with tail wind: 44-45mpg

Shell V power unleaded less than half tank full with strong head wind: 37-38mpg

The wind obviously causing quite a hefty deviation here of around 7mpg.

Averaging out results to account for the wind factor giving around 41.5mpg which makes it more or less consistent with my previous results.

Actual mix upon filling before tests was 63 litres of V power meaning around 7 litres of residual standard unleaded diluted in the mix.

Probably the next time I add more results will be after another full fill on v power to see how a purer mix affects things.

[lizzard-t]

Good results there .
is this average MPG from a full tank to when it requires filling again ( ie a complete full tank, through to empty? )
but it seems you are really happy with the results you are achieving.
Keep us posted .

[Bob1983]

Good results there .
is this average MPG from a full tank to when it requires filling again ( ie a complete full tank, through to empty? )
but it seems you are really happy with the results you are achieving.
Keep us posted .

They're not results of a full tank, but more a live readout of how the economy works out over the same stretch of road to make comparions using the average the car tells me. Just a way to monitor any improvements after using the redex and now taking it further running on shell v power.

The average mpg would be a fair bit lower across the course of a whole tank but I can already see just by the ecu remaining mileage added to the trip accumulation (reset upon filling up) that the overall mileage has gone up quite a lot. I think I was getting about 475 miles on standard unleaded before I used the redex, and after using it, it was predicting around 520 and now with v power predicting around 550 (and sometimes slightly higher when cruising). Of course this is quite loose and approximate but the overall trend is on the up!

I'll report back what the ecu is telling me remains when I'm nearly empty and add that to the trip to get a rough idea of what it will be over a full tank!

[Bob1983]

Just back from another test run on my second tank of V Power unleaded 99 Ron.

Keep in mind that my previous fill was mixed with remaining 7 litres of standard unleaded to the 63 litres of V power going in, therfore diluting the mix and lowering the octane somewhat on the previous tests. So this time the tank contains a much purer mix.

What was interesting upon filling up this time was the miles remaining on the ECU which had yet again gone up, to 575 miles from the 550 it predicted on the previous (first) dilluted V power fill.

Did the same test route again with similar conditions to previous, although this time much less wind if any. That is, same long stretch of dual carriageway between two junctions resetting the average mpg counter once at cruising speed 65mph, and resetting it again on the return trip in opposite direction back to the first junction to compare the end results.

I got a consistent 42-43mpg readout upon reaching the finish in both directions after 4 passes/resets on the same stretch, and at times briefly touching on 44 but only really where on a slight downhill. So the realistic measurement is 42-43mpg for the purpose of the exercise.

These are great results given that the fuel tank weight was only about an 8th down from full. The remaining miles even went up higher from the initial 575 while cruising like this, mostly floating between 580 and 590 and even peaking 595 at one point! So it seems that the richer mix of V power in the tank has yet again improved the economy. Obviously with varied driving conditions this projection is only loose but it still shows an upward trend which I find pretty interesting.

Will probably head out for another run at some point in similar outside conditions when the tank is half empty or less to get a read on if there's an even greater increase upon reduced weight. For the sake of consistency!

Contrary to popular opinion, hopefully my tests are going some ways to showing that the lowly 1.8 petrol is actually capable of good economy in favourable conditions with a clean fuel system / internals.

Furthermore, after doing some rough calcs comparing the costs of running standard unleaded vs v power, with the increased milage I am seeing, the fuel costs actually work out about the same (breaking even) on a per mile basis, or a tiny amount cheaper. So by the time you account for the increased mileage of V power, it pays for itself! So you have less visits to the forecourt and a healthier, more responsive car. This obviously depends on the car, and not the general rule. But for me this is how it breaks down based on the current rates from the Shell garage near me:

70L tank x £1.66/L = £116.20 (525 miles) std 95 (E10)
70L tank x £1.79/L = £125.30 (575 miles) v power 99 (E5)

£116.20/525 = 0.221p/mile standard 95
£125.30/575 = 0.217p/mile v power 99

So approximately 22p per mile on either fuel. The added benefits of the V power make this a no brainer in my case.

Although I should stipulate that the results I was getting of 525 miles for standard unleaded was sainsburys unleaded, not Shell - so I don't know if there would be any variance there but one would assume most likely not much.

Would love to hear in this thread what others have been getting from their 1.8 petrol insignias. Or maybe this can help others to see what is possible.

[Felix]

An older post I know, but thanks Bob1983, I have been trying this with my 1.8 petrol. Car would barely do more than 33 mpg when I first got it, after a good amount of long runs that average rose to 36, still not quite great I thought so tried Redex, got it half price at Tesco for only £2.50! Half a tank done already after a very long drive today and has returned a solid 38.7 mpg so far. The 1.8 will never be a fast car but the car already felt more responsive as soon as I put that stuff in. I've no doubt when summer comes round again it will achieve the magical 40 mpg with very long drives, it is colder now as well so anything around 38 mpg is good right now. I've been working out the MPG manually as well, not just looking at the trip computer, though it does seem very accurate for averages.

My trip computer used to show a total of only 495 miles range as well, but now after filling up says it will do 575 miles or more range!

Not tried premium super unleaded fuel yet (because it is over 1.70 a litre!!) but if it performs as good as this with the odd shot of redex for just £2.50 a half tank now and then, its a no brainier I will just treat it to a shot of that stuff now and then.

[Felix]

Well would you believe it after quite a few shorter drives the last couple of days the average MPG it still maintaining around 36 - 37! A drop of only about 2 MPG from the longer drives, whereas before it would immediately drop a lot more to 29 - 32 after a few short drives. That RedEx stuff really works, (and I don't work for whoever makes RedEx by the way)

It should be remembered however I drive like an old man and keep the car in good condition as well (tyre pressures top, car serviced, light as possible no crap in the boot, etc)

Who knows, maybe next summer I'll get 90000 MPG on a long drive not just 40 MPG haha

Joking aside, it is well worth a shot for all you guys out there with the 1.8 petrol engine, which contrary to popular belief can do more than 33 MPG!!

[Felix]

Well its below freezing now and the MPG is still around 34 -35 with mixed driving (some short drives less than 6 miles, some only a bit longer), not bad considering it is much colder now.

[Jon199102]

Although I drive a diesel I have been using the Hydra additive stuff on Amazon.

At first as anyone I was sceptical over it's claimed results though noticed after after the second fill of diesel it was running smoother and getting more miles before a regen.

Since I work on my car I generally understand how the map and EGR will look like after 10k. I noticed less soot overall so appears to be having a good effect.

Noticed winter wise the start up is much smoother too. They make petrol versions so likely similar effects to redex

[Felix]

Thanks, yes I have tried Redex and similar stuff also and there has been a slight improvement in MPG and throttle response. I'm quite happy with the MPG now, it is just a 1.8 petrol engine in a 1.5 tonne car after all.

The overall results are 33 - 35 MPG in winter/short drives, and in summer 37 - 40 MPG on long drives, I'd say it all seems about right for this engine, and the cars size and weight.

The fuel additives definitely worked though and cleared the injectors, because like the original poster in this thread I was barely getting 33 MPG no matter how I drove it, so it needed a fuel system cleaner for sure.

[Felix]

Final update on this for me for anyone still interested - I went back to using supermarket basic E10 fuel as that was cheapest in my area just to check I wasn't imagining things. After just a couple of tanks of the cheap stuff the car is back to noticeably sluggish performance and also struggling for 32 mpg. Moral of the story is.... if you have a 1.8 petrol Insignia, it is well worth a shot of redex in your tank now and then, along with brand name E10 petrol (Shell, BP, whatever) or just use any premium super unleaded. The extra MPG and performance is well worth it from this, so try and avoid cheaper supermarket basic fuel, however tempting it is to use just because it is cheaper.