Hello everyone, i have just bought a 2011 Megane RS250 and i suspect that it has high fuel consumption. The car is not heavily modified, it only has a remap to 300hp/420nm, a Forge recirculation valve and a midbox delete. When driven hard, the car gives me an average of 16.8L/100km (16.8mpg) and up. If i drive a little more carefully I have seen it drop to 15.7L/100km (18mpg) max. The board computer is quite accurate as i have tried calculating the consumption the old way by filling it up 2 times in 100km and it turned out to be 16.6L/100km (17mpg). There are no trouble codes present, the car sounds and runs fine and it pulls strong through the rev range. I have noticed that the temperature gauge stays a bar below the middle but that is about it. I have also put a fuel additive as a preventative measure and I also use 98 octane. Is this normal or is there an issue that should be looked into? Thank you all.
My fuel consumption dropped, 1 changed the thermostat and gained 5/6 mpg, my car is forged, bigger turbo running just over 400hp and on a run it will return 30mpg on track I can get it down to 8/10 mpg
So you are saying the thermostat could be the problem? Also should the needle stay in the middle of the gauge?
It's a strong possibility, my 265 needle was vertical, but the 250's are supposed to be a little lower, I think halve way between the two lines. I've changed the thermostat in my 250 and it's now nearly vertical
Its a flash map i think, i bought the car mapped from the previous owner so im not sure. I just checked the original number of the thermostat because i want to change it just to be sure and the number is 8200772990 which seems to be an 83°C but i can also see that there is an 89°C option. Which one should i go for?
I suppose that there is always a possibility that the remap is also bad and creates a rich air/fuel mixture but i have not noticed black smoke caused by excess fuel from the exhaust. These cars are extremely rare in my country and people dont have a lot of experience remapping them so its only a wild guess... Could this also be the case?
iA flash map isn't good, all engines are different even if they are the same. f it was me then i would go with the 89c one, engines don't like to run cold, more wear with a colder temperature.
I'm sure it will be running rich, that to keep your engine on the safe side, but if yours is off then it can add to the extra fueling
Well i will start by changing the thermostat first and i will order new original NGK spark plugs (gapped to 0.6mm because as i have read on this forum thats another improvement i can make) as preventative maintenance and we will see how it goes from there. If that doesnt work out worst case scenario i will have to go to another country to get it remapped again because this excess fuel consumption is bugging me. On a side note i have also read the fuel consumption figures on a website where i can see all possible factory specifications of the car and it says that realistically the consuption is 14.4 - 17.3L/100km in the city so i dont know what to say anymore...
If your replacing the spark plugs, go one number higher, instead of 7's go for some 8's, still gap them to 0.6mm, there better for mapped engines, mine will be running 9's as it will hopefully be running 450 to 500hp You seriously need to get a proper map on it, where in the world are you????
Well the factory ones are IFR7X8G so they already are 8s on the heat range if that is what you mean. Also isn't it better to run a colder spark plug for a tuned engine or am i wrong? Im from North Macedonia btw, you probably have never heard of it lol. I need to go to Greece to get a tune as they are way more prepared for tuning sports cars.
That's not a good number, it should be BKR7EIX, so go to an 8, i thought the higher the number the colder the plug
The OE number for the plugs is 8201001947 and when you cross reference it, it comes out as NGK IFR7X8G and they are good up to 350bhp, the BKR7EIX (and colder) model you mention is used in cars that are heavily tuned, at least that's what K-Tec says. If i can't find the the original ones i will probably go for the ones you mentioned.
bare in mind that these cars are tuned by guesswork after tune setup put toghether by Henk from RSTuner in Netherlands . in few very few words , this ECU is an torque based system and requires specific math calculations. extrapolations of the torque maps , etc are indispensable for the functionality of the complete system. some "renault specialists" will run the car on the rollers hours and hours (expose to risky tests and needlessly produce a very high rate engine wear) to guess find by trial and error things that must be precised calculated in excell in 5 minutes by professional tuner / data engineer. also seems they all use the Henk`s receipt and apply blindly this to differeny setups , etc very few are thinking outside the box and the clients are completely ignorant of many things are done to their cars behind the curtain... on FB they are all batman`s Renault Specialist but if you open their work in Winols and compare with professional tuner setup is all came to light ... I have ... so do not expect that your cluster fuel consumption is aligned with the real figures because is all decalibrated now. just live with that , or you need professinal work a trip in France to: Chasel chazeltechnologiecourse.com but they are very very hard to get to.... or RSTune Alsace https://rstune.alsace/
Coming back to this, I replaced the thermostat and the spark plugs, and the consumption slowly started to drop and currently it sits at 15.0L/100km (18.8 MPG) and almost never goes above 15.2L/100km (18.5 MPG). So the thermostat was one of the problems, however I still think that the consumption needs to drop so my next move will be taking the injectors out and have them cleaned, as well as replacing the fuel filter while I'm at it. Also if I leave the car to idle while it is hot, or after a faster drive, I can hear a random thud coming from the gearbox side of the engine. It sounds like a misfire, but the coils and the spark plugs are good, and the car pulls strong all the way to redline. I am 90% sure the sound is coming from the DMF because the sound that I'm talking about doesn't appear with the clutch pressed in. I can also hear it when I turn the car off with the clutch pedal released, and with the clutch pressed in the sound is not present at shut down. Has anyone had any experience with fuel consumption being better after cleaning the injectors? I also want to hear your guys thoughts on the sound coming from what I can only guess is the DMF...
something is not right. you need to pull out the sparkplugs and see the color. best way is to install a wideband AFR sensor and test. also you can put back the original file in the ecu and re-test. where are you based? the EMS3110 does run quite rich from stock. (for the record my car with 720cc injectors and BW EFR6758 uses average 9.5l / 100km on spirited driving and some highway driving)
The color of the spark plugs is perfect, i have checked that. After i clean the injectors i will have to take it to the shop that had the car remapped so they can check out what is going on. At this point im very confused, the car has no ECU errors, no check engine light, runs and drives fine and doesn't show mechanical signs of a rich air/fuel mixture. I will post an update to this thread if I find out what the problem is.
