Unleaded. 95ron or 97/99 ron???? Advice pls.

[Vin-R]

Hey guys, quick question. Since ive had my stage 1 CC remap, ive tended to use super unleaded. Car seems to run smoothly on this. However, the other day my wife filled up with normal 95ron. Now when i plant my foot in 3rd, 4th etc, car seems to hold back and hesitate through the rev range?? U can hear the turbo winding up then slowin down sort of thing when the car hesitates and holds back.

Strange thing is, ive not noticed this wen the cars running on tesco super or shell vpower. Is there any reason why? Or could there be somethin. Wrong woth the map? Bought and fitted a new maf at the weekend so it cant be that?!?

Also, when driving normally, does super unleaded get used up quicker than normal 95ron??

Thanx in advAnce as usual.

Vin

 

[andycupra]

so, you usually fill up with super.
you got car remapped...

the wife put 95 ron in and the car runs like pants.

and you want to know what causing it???

(most maps will b ewritten on the assumption that you will be using super... ) however usually the ecu will not take long to adapt to the new fuel..

and no super doesnt get used more quickly than normal 95 ron. i think the ron rating is something to do with its resistance to ignition, so if you have a higher ron rating you may get a longer burn and/or more resistance to preignition. Which allows more agressive timing to be used.
This doesnt mean you use more fuel, it should mean you can potentially get more power from the fuel.

Many people will swear that they get better mpg running super/v power.

 

[Vin-R]

Ah thats great andy cheers! Yeah i was beginning to think there maybe something wrong with the map etc. At the time the map was put on i was running 95ron. But yes, since the map the car feels so much more alive and quicker on super or vpower. Power comes in smoother too!

My bro in law got his LCR map done from p-torque and he runs normal 95ron all the time and he dont get any hesitations or car pulling back through the rev range?!?!? Dont know why.

 

[andycupra]

interesting that you had it filled with 95 when remapped, in which case the map really should have been set up for that. However i dont know if they checked this.

If you run super for a while the ecu (even if it has been remapped) will adapt to some extent and so if you then put in 95 ron it wont run right.
However, as ive said the ecu will not normally take very long to pull things back and have it running ok on 95 ron...
So im interested to know how long you have been running with the 95 ron and also where did the fuel come from? (all fuels are NOT the same)

 

[Vin-R]

Hmm strange isnt it. When i called custom code about this, the guy did say that recommend 97 + ron as thats what their maps r based around. They themselves are using tesco super whih is 99ron and he said theyve had good results from it. Vpowers to expensive. Wife filled up 40quid on fri evening. Took it out tonight and its hesitating in 3rd and 4th around 5 -6 k revs. Is there anything else it could be? Boost leak?

 

[cupra-rich]

new maf not work then vin? i know a few lcr owners who only run tesco 99 ron no problems on there mapped cars. gota use the best fuel to get the best from your map imho.

 

[Joeb]

i think you should ban the mrs from driving the car, problem solved


but i agree, your ECU will adapt when you give it a few FULL tanks of super unleaded.

my mapped LCR ran completely **** after putting in normal unleaded (didnt have a choice at the time). it did take 1/2 full tanks to get back to normal

hope that helps.

 

[DannyC87]

It is the crap fuel. When a car is mapped they tend to adjust boost and timing. If lesser octane fuel is used the ecu will detect predetonation with the knock sensors; triggering the ECU to pull the timing back (what you are feeling as hesitation). If you were to log with vagcom you would see high timing correction factors due to the lesser octane petrol.
Mine is p-torqued and runs alot better on 99..but if I used 95 all the time I would not notice the hesitance as I would not have experienced how good the map is on 99!

 

[TubbyTwo]

The higher the RON (Research octane number) the more resistant the fuel is to detonation and pre-ignition from the higher cylinder temps.

Mine was mapped on Optimax so i use that or Tesco 99.

be gentle with the car until thats gone, then fill up with some decent stuff. Then never let your wife go near a petrol station in it again lol

 

[Muttley]

The LCR's standard map works best with premium (98 RON) fuel. A remap will push the boost and timing further and will expect you to use high-octane fuel to realise the benefits of the map. Using 95 RON will pretty much negate those benefits.

The advantage of turbocharging (or any form of forced induction) in a car is to increase the cylinder pressures, shoving more air in at each stroke: it also effectively increases the compression ratio. Both of these factors render the engine more susceptible to pre-ignition or knock. Higher octane petrol is formulated to reduce pre-ignition, by being harder to ignite (and also slower to burn). 95 RON petrol in your LCR *will* cause knock.

Nearly all cars with electronic engine management have knock sensors on the crankcase, which detect the onset of knock and retard the ignition timing to prevent it destroying the engine. Leons are no exception.

Filling your remapped car with 95 RON will cause the ECU to retard the ignition as it detects the onset of knock, reducing the power output. This is separate from the adaptive learning that the ECU performs to take account of long-term changes in driving style, fuel quality or altitude. The knock sensor output modifies the ECU parameters immediately.


In normal use the 95 RON petrol should get used up slightly faster, as the retarded ignition makes the engine less efficient. However it is more likely that you will see the premium fuel disappearing faster, simply because it encourages heavier use of the right foot.

 

[andycupra]

well said!

 

[t0m]

Again, Muttley - very well put! Spot on.

I use premium 98 and nothing else. EVER. I didn't buy an LCR to skimp on petrol. I want it to be running at it's best all year round, and it's fastest

 

[Vin-R]

Hi Guys thanks for all your feedback!! really appreciate it! t0m just for the record mate, i didnt buy my LCR to 'skimp' on petrol either. When my LCR was standard it was absolutely fine on 95ron, and pulled well in all gears and at 5yrs old, she still produced 224bhp and 209lbs at a P-Torque Rolling Road Day. Ive had REVO and JABBA remaps on my old 1.8T Golfs and was advised that the maps were fine to use with normal 95ron fuel and i never had any problems. However with the LCR being higher powered, i was using super unleaded after the CC remap, my mrs put 95ron in not knowing, So i was just concerned as to why my LCR was pulling back and hesitating, and thanks to you guys i now know!

Cheers to Muttley too! Sounds like you know your stuff mate! Your right abt 95ron being used up quicker. My Mrs put in £40 last friday(exactly on 3/4 tank. All I did was blast around for a bit after, and it felt like it wasnt right. went to leicester and back on saturday (about 55mile round tripand full car) and a few trips here and there on sunday. and my wifes been to work mon and tue and the light came on today and i thought naa petrol cant run out that quickly

thankyou for all your help! i love this forum!! haha

ps, Hi RIch, the MAF did make a bit of difference but not a huge amount. I think it was mainly a case of using 95ron unleaded when my remaps made for higher (98+) RON fuel. Might see u at the local meet tomorrow! lookin to be a hot day!

 

[Jezeky]

Juwt a quick question. I've had my car mapped on 95ron last week and from what I read if I use premium 98ron or 99ron my ecu over a few days will adjust to the better fuel and it will run better? I. E. Few more BHP and torque and MPG?

Just want to double check. It's what I seem to understand from this thread.

Kind regards

Jezeky

 

[mty12345]

Hi mate. These cars were designed to be run on 98 octane from the factory. They will run without damage on 95ron but with reduced performance even on a standard car.

When you say you had it mapped on 95ron, it take it you mean someone just flashed a remap to the ECU, rather than someone actually live mapping it on a rolling road on 95ron? As i can't see any decent mapper would live map something on crap fuel.

If it was just a map that was flashed to it, then yes 99ron is needed from now on.....that's either shell v power or tesco 99. With anything less than 99ron on a remap, the ecu is constantly having to pull back the boost and timing to avoid destroying the engine.

 

[Jezeky]

Hi mate. These cars were designed to be run on 98 octane from the factory. They will run without damage on 95ron but with reduced performance even on a standard car.

When you say you had it mapped on 95ron, it take it you mean someone just flashed a remap to the ECU, rather than someone actually live mapping it on a rolling road on 95ron?If it was just a map that was flashed to it, then yes 99ron is needed from now on, that's either shell vpower or tesco 99. With anything less than 99ron the ecu is constantly having to pull back the boost and timing to avoid destroying the engine.

Eyup bud! Thanks for the quick reply. It's a seat ibiza fr 1.2 tsi 2015 105PS it's now at around 136BHP with the remap, k&n air filter and mid box replaced with a straight pipe.

They didn't use a dyno. Just had it in garage for half a day and did all work to it and made it the BHP it is now on regular 95ron fuel.

I was just wondering if it would be more beneficial for me to use higher Oct fuels?

Jezeky

 

[mty12345]

Ah right, you are in the wrong section buddy. This is for the MK1 cars from 1999-2006, you need the mk3 section for your car. Having said that , exactly the same thing is true for your engine. Shell vpower from now on mate.

 

[mty12345]

Mk 3 section ..... https://forums.seatcupra.net/index.php?forums/leon-mk3.309/

 

[Jezeky]

Mk 3 section ..... https://forums.seatcupra.net/index.php?forums/leon-mk3.309/

Thanks bud!

OK so even its been mapped on 95ron I should still use 99ron shell or tesco for best bhp and overall performance?

Jez

 

[mty12345]

No worries and yeah definitely. By now your engine will have realised that it has to reduce boost to account for the 95, so it will take a bit of time to adapt itself to the better petrol (maybe even upto a couple of hundred miles or so) .The more you floor it and ask for maximum performance, the quicker the ecu will learn that you now have 99 in there.
Once it adapts to that then you should have the extra torque all the time, but more importantly it will also protect your engine from any possible damage caused by the 95. Any car with a turbo should always be run on 98 octane at a minimum really, The extra heat and pressure generated is enough to cause low octane fuels to ignite from the heat rather than when the spark plug fires (called knocking or detonation). If this happens when the piston is still on it's upward stroke, then extreme downward pressure can bend or even snap the connecting rod which connects the piston to the crankshaft, the engine will be damaged beyond repair and you'll have mega bills.