just put 95 ron in, problems...

85genius said:
I alternate don't know why really as don't notice the difference but mine is due a tank of the good stuff this time
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+1
Especially on an NA car although there will be a slight difference in terms of performance it wont really be noticeable its more the cleanliness of the fuel and its clearing of lines/injectors etc that helps keep everything smooth :thumbsup:
 
Flyingfifer said:
85genius said:
I alternate don't know why really as don't notice the difference but mine is due a tank of the good stuff this time
Click to expand...

+1
Especially on an NA car although there will be a slight difference in terms of performance it wont really be noticeable its more the cleanliness of the fuel and its clearing of lines/injectors etc that helps keep everything smooth :thumbsup:
Click to expand...
Yeah that's kindof my thinking, she's getting on a bit and has a fair few miles under her belt so cant hurt to put the good stuff in
 
I've been doing a bit of reading on here and the symptoms sound like they may be caused by a dirty vanos solenoid although as yet I've had no fault codes logged. Could this have been present already but emphasised by the lower octane petrol? I'm thinking of pulling them both out to clean this weekend to see if it improves.

Thanks
 
This happened to mine a year ago. I originally put it down to bad fuel, but then it persisted more aggressively even with VPower/Tesco 99.

Eventually it did it consistently under high load, low rpm situations and dropped a cylinder all together on one journey - i didn't get a fault code or EML and was too sympathetic to push the car to that point. I self-diagnosed that a coil-pack was failing, so i swapped out number 5 (theoretically the one under the most hostile conditions due to the heat). It fixed it first time!

If you're changing a coil pack without an EML, id do it in the following order: 5,6,4,3,2,1.
 
funnily enough I replaced number 5 a couple of months ago and not had any issues or faults. It's also running loads better now it's back on optimax... I'm going to clean and swap around the vanos solenoids this weekend so will report back if any difference.
cheers
 
I almost exclusively use 99 RON. I do find I get a few more miles out of a tank compared to 95, certainly enough to cover the extra couple of pounds.
I have run on 95 a couple of times and have had no issues.
 
craig3.2 said:
Always used 98 in 8) my 3.0,and my M...the one time I put 95 in my M,shortly after getting it,an no2 sensor went faulty,and drove hellish,stuck to super ever since.
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Exactly this for the MC.

Put half a tank in of BP 95 in ( local garage doesn't do 98 :roll: )
stuttering on warm-up and start
P301,302,303 fault codes, ( misfiring cyls 1,2,3) then Bank 1 02 sensor "running rich" (forget the fault code for this)
Swapped plugs and coils bank 1 to 2, still same,
cleaned out all the intake piping, and ICV - then did throttle reset, still the same
bit the bullet and fitted a new O2 sensor, immediately car back to being awesome.
 
Yeah,they do prefer higher octane fuels,and tbh,would never use anything else in a performance car,as farback as I can remember,in hot hatches too,as all max bhp,etc is quoted using hi octane fuel.

Not worth the couple of quid or so per tank saving,IMO :driving:
 
The car will perform better on higher RON however. It won't magically explode on 95.

If your car is having issues with supermarket fuel then it's not the fuel it's the car.

I use V power just because I don't care about the £5 difference per tank.
 
SonnyA85 said:
The car will perform better on higher RON however. It won't magically explode on 95.

If your car is having issues with supermarket fuel then it's not the fuel it's the car.

I use V power just because I don't care about the £5 difference per tank.
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True,it won't explode,but the m's do have a habit of running like crap on 95,it has happened to a few ppl I know of,and myself......my car ran like s**t, coughing and spluttering after filling up with 95 one time,when running low,and had no other option,it then had a faulty 02 sensor as a result......shouldn't happen I agree,but it does.
In my case,I would put it down to possibly something in the fuel from the Petrol Station I used that time,as dirt and stuff may have been in the bottom of their storage tanks.

Safer sticking to hi octane :driving:
 
craig3.2 said:
SonnyA85 said:
The car will perform better on higher RON however. It won't magically explode on 95.

If your car is having issues with supermarket fuel then it's not the fuel it's the car.

I use V power just because I don't care about the £5 difference per tank.
Click to expand...

True,it won't explode,but the m's do have a habit of running like crap on 95,it has happened to a few ppl I know of,and myself......my car ran like s**t, coughing and spluttering after filling up with 95 one time,when running low,and had no other option,it then had a faulty 02 sensor as a result......shouldn't happen I agree,but it does.
In my case,I would put it down to possibly something in the fuel from the Petrol Station I used that time,as dirt and stuff may have been in the bottom of their storage tanks.

Safer sticking to hi octane :driving:
Click to expand...

Again that is a myth I cannot believe people still believe.

Cars have fuel filters. What is the purpose of the filter if it allows dirt and stuff to get into the engine?

I'm also betting refineries have filters as do petrol stations, etc. I'm just guessing here but you would think that they would do to stop issues should something get in there that shouldn't.

I think all performance cars are designed to run on 95 minimum. However it should tell you in the manual if you have a look for the exact spec that should be used. Would be interesting to see what it says in the M manual. Basically the car shouldn't have any issues with 95, it will still work 100% fine. It will however run with a bit more power and refinement on the better grade stuff.

I've used a tank of BP Ultimate and £20 of performance fuel from a non major branded station. The car ran the exact same on all 3 IMO.
 
SonnyA85 said:
Again that is a myth I cannot believe people still believe.

Cars have fuel filters. What is the purpose of the filter if it allows dirt and stuff to get into the engine?

I'm also betting refineries have filters as do petrol stations, etc. I'm just guessing here but you would think that they would do to stop issues should something get in there that shouldn't.

I think all performance cars are designed to run on 95 minimum. However it should tell you in the manual if you have a look for the exact spec that should be used. Would be interesting to see what it says in the M manual. Basically the car shouldn't have any issues with 95, it will still work 100% fine. It will however run with a bit more power and refinement on the better grade stuff.

I've used a tank of BP Ultimate and £20 of performance fuel from a non major branded station. The car ran the exact same on all 3 IMO.
Click to expand...

Not necessarily true. 2.5si and 3.0si owners should be fully aware that their car does not have a fuel filter.
It has a basic mesh strainer built into the fuel pump, but no replaceable / serviceable fuel filter.

If a car's mapping has been done so that it requires 98 RON fuel to run its best, then ideally that's what you should run. Of course you can put 95RON in there, I may run a little odd for a half mile or so, but by the time you get to that point the ECU will have had readings from the knock sensor requesting it to slightly retard the timing to keep the engine running safely.

The safety systems within your ECU are very very quick to take things away in order to keep your engine safe, but very slow to put them back.

So when you hear of people feeling a huge difference as soon as they start to run 98RON fuel, that's total bull... It'd take at least a quarter tank of the stuff before the ECU would be allowing the timing / ignition to be back in a position where it will give the optimum "requested variables". I very much doubt anyone would really be able to "feel" the difference anyway.

It'd be like asking someone to see the difference between 250ml of water and 251ml of water.
 
Ok well I cleaned and swapped my vanos solenoids today, bit of a pain to get to and stubborn to get back in after but managed to get it done between showers... Just been for a spin and didn't notice any hesitation under full throttle at any revs so seems to be ok now. However I would say that it improved after putting Optimax back in last week so still think it was something to do with the petrol.

One positive bi-product of the solenoid swap seems to be improved power in the mid and top range. This might be due to the solenoids having to operate in different ranges/profiles now so behaving like new? I'm guessing but these are moving parts so must be subject to wear and are known to fail like crank sensors etc. Anyway, hope this useful for someone.
 
SonnyA85 said:
craig3.2 said:
SonnyA85 said:
The car will perform better on higher RON however. It won't magically explode on 95.

If your car is having issues with supermarket fuel then it's not the fuel it's the car.

I use V power just because I don't care about the £5 difference per tank.
Click to expand...

True,it won't explode,but the m's do have a habit of running like crap on 95,it has happened to a few ppl I know of,and myself......my car ran like s**t, coughing and spluttering after filling up with 95 one time,when running low,and had no other option,it then had a faulty 02 sensor as a result......shouldn't happen I agree,but it does.
In my case,I would put it down to possibly something in the fuel from the Petrol Station I used that time,as dirt and stuff may have been in the bottom of their storage tanks.

Safer sticking to hi octane :driving:
Click to expand...

Again that is a myth I cannot believe people still believe.

Cars have fuel filters. What is the purpose of the filter if it allows dirt and stuff to get into the engine?

I'm also betting refineries have filters as do petrol stations, etc. I'm just guessing here but you would think that they would do to stop issues should something get in there that shouldn't.

I think all performance cars are designed to run on 95 minimum. However it should tell you in the manual if you have a look for the exact spec that should be used. Would be interesting to see what it says in the M manual. Basically the car shouldn't have any issues with 95, it will still work 100% fine. It will however run with a bit more power and refinement on the better grade stuff.

I've used a tank of BP Ultimate and £20 of performance fuel from a non major branded station. The car ran the exact same on all 3 IMO.
Click to expand...


According to a BMW M tech,the z4's do Not have a fuel filter, which I found strange,as my 2year old cavalier(back in 1990/92)had a fuel filter....the z does not.

Also,it's not a myth that several people have had problems as soon as filling up with a full tank of 95ron,and it damaging 02 sensors......it shouldn't happen in a car,especially a BMW/premium brand,but it does....happened to me,and was not a myth or a dream,but Fact,and I know others have had this same issue.
So let it be with coming back at me,saying what I am saying is crap,Iam talking from my own experience, and from what I have seen/heard from other owners!!
 
The above is indeed correct! It would appear they only have the strainer on the in tank lift pump on all Z4 models!
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If you saw the crazy s**t some of the labs do with o2 sensors a bit odd odd fuel isn't going to screw them. More than likely they were on their way out and the larger than normal change just finished them off.

It's true that a car turned for 98 will run worse on 95 but the z4 is not running on some simple ecu. I'd be surprised if it didn't have a closed loop system to cope with changes in fuel. Hence the total bull s**t that as soon as you put 98 in its faster
 
Don't think anyone's claimed it's faster mate. You're then guessing at something then drawing a conclusion based on that guess work.

My car ran badly on 95, might have been bad batch, who knows. It's now running fine again 98.
 
Daily Mail science I'm afraid JimBob78. There is no way you would be able to detect the difference between 95 /97/ or 99 RON fuel with a modern EMU and on only one tank. As for failing sensors .. bollocks this is what is called auto-correlation or mere coincidence. The higher rated fuels tend to have better additives which ARE beneficial but only after several tanks of the poor stuff. Source ? My chief engineer's wife who is a Ph.D fuel specialist with BP :-)
 
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