XR8 fuel question

sednwol · 20-06-2006, 10:41 AM

As you know I have just got my XR8 S3 and through out its previous life it ran on Caltex Vortex. I had my first fill up and put in Shell PULP '95, and now the cars idle (in drive) is a little rough. I don't believe the fuel is "bad". Could this idle isue be due to the change of fuel? I have also heard that the ECU (or whatever) will "dial in" the new mix and adjust, is this true?

Also,what fuel do you XR8 owners use?

XR6-VCT-2000 · 20-06-2006, 11:49 AM

I own a xr6 so bit of different kettle of fish, but still , it could be just the 2 types of fuel mixed ( the old and the new ) creating a wierd effect maybe ??. As far as the ecu 'learning' the octane level of the fuel , im not sure it does - I think it's possible to get your car tuned to run better on higher octane fuels etc etc , but the ecu just works out the fuel/air ratio according to the engine/coolent temp (during warmup) and the o2 exhaust sensor when warm & running i think. ?

Whatever the case , gone are the good old days of the air/fuel mixture screw on the side of a carby ! ..lol

Good question though , as i have noticed if i run on normal unleaded my car is a slug and idles like rubbish ( i get real bad economy too ) , 95 octane aint bad in my car , seems to idle smoother and the economy is a bit better and performance too , but in the end i stick to the 98 as i seem to get the best bang for buck , even though it cost more a tank seems to last me way longer , way better economy than the other 2 fuels , very noticible on how far down i have to put my foot into it too when using different fuels to obtain the same sorta torque/power. Allways runs like a gem on the 98 too ;) .

sednwol · 20-06-2006, 01:40 PM

Hmmm, Vortex is rated 95, I thought it was 98. I thought that was my answer. Well if 98 will get me further per tank then price is really realitive and performance and a "cleaner" engine is the result.

XR6-VCT-2000 · 20-06-2006, 01:46 PM

Don't quote me on everything i said above , thats just in my case , with my car / you might find it the same for yours too, maybe ?

.. And as for the other stuff on the ecu im not 100% sure about ! , i thought i'de at least just start this thread off , as there was sooo many looksys but no replys. ;)

sednwol · 20-06-2006, 01:49 PM

Hopefully some of the guys with XR8's will give me some feedack re the fuel they use etc and whether the ECU (or whatever) will "dial in" the new mix and adjust. Thanks XR6-VCT-2000.

XR6-VCT-2000 · 20-06-2006, 01:51 PM

;) , np ... i'm sure i'll probably get backlash over what i said ..lol , thats cool though , as i'de like to know 100% for sure too . cheers

SIKXR8220 · 20-06-2006, 01:59 PM

Hey mate i always use shell pulp 95 only because its the closest one to me and my car does idle a touch rough, i am not saying its the fuel but from what you have said it could be, i might whack a tank of ultimate in and see what happens. As for the ecu question i wouldnt have a clue, soory.

sednwol · 20-06-2006, 02:16 PM

Quote:

i might whack a tank of ultimate in and see what happens.

Definitly worth a try. My car (Series 3) didn't miss a beat on Vortex (95 ron) by boy it doesn't like the shell 95.

SIKXR8220 · 20-06-2006, 03:05 PM

Quote:

Originally Posted by sednwol

Definitly worth a try. My car (Series 3) didn't miss a beat on Vortex (95 ron) by boy it doesn't like the shell 95.

Shell is claiming that their 95 is the most economic of the 95's

XR6-VCT-2000 · 20-06-2006, 03:09 PM

lol , for the few cents extra , but for the piece of mind and no problems and good performance, i'll stick to my 98 hi octane fuel tyvm ..lol

sednwol · 20-06-2006, 03:34 PM

Yep, Iam going to try it!

**FTE217** · 20-06-2006, 03:36 PM

I have never run 95 in my S3XR8, 98 is the only go for better everything,far out weighs the savings pumping 95 in the tank.
My T3 will be the same nothing but 98 or 100.

sednwol · 20-06-2006, 03:48 PM

Yep Iam sold! No doubt this will fix the rough idle. :hihi:

galaxy xr8 · 20-06-2006, 05:16 PM

I run BP Ultimate in mine, I used to run Opticrap vbut found it to inconsistant, I have never had a problem with Ultimate and mine idle's nicely.

HLC · 20-06-2006, 05:20 PM

91 RON woolworths petrol for me :hihi: cant afford anything better

:

sednwol · 20-06-2006, 05:23 PM

Quote:

I run BP Ultimate in mine... I have never had a problem with Ultimate and mine idle's nicely.

I get discount tickets for the local BP, I'll try the ultimate

galaxy xr8 · 20-06-2006, 06:00 PM

Quote:

Originally Posted by sednwol

I get discount tickets for the local BP, I'll try the ultimate

How do you get that, that would come in handy.

sednwol · 20-06-2006, 06:14 PM

Quote:

How do you get that, that would come in handy.

Shopping at Ritchies supermarkets. If there's one in Bendigo they probably do a deal with the local BP.

ReVd_uP · 20-06-2006, 06:24 PM

AU XR8 at close to 100 000 kms? id be looking into leads for the idle concern, or you could wait till it starts missfiring, wouldnt hurt to change plugs either, in answer to you other Q, i run my xr8 on 98, although mines been edited

xd5.8l · 20-06-2006, 06:29 PM

They all idle like crap but all is forgiven when the right foot hits the firewall

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sednwol · 20-06-2006, 06:40 PM

Quote:

id be looking into leads for the idle concern,

It was idling beautifully until I put the Shell '95 in, sure leads will be soon but that's not the issue at present.

xd5.8l · 20-06-2006, 06:42 PM

start her up now sednwol and watch the firworks. Close the bonnet on yourself so its extra dark if anyone asks you what your doing tell them to f$%k off.

sednwol · 20-06-2006, 06:44 PM

: Great advise mate!

8pAc · 20-06-2006, 06:45 PM

My series 3 xr8 like optimax better then ultimate, my older 6 liked it the other way round.

fordAU · 21-06-2006, 08:00 AM

Correct me if I am wrong but as far as I know the 200/220's are tuned for 95 octane.

On a 220 I have found no difference between 95 or 98, if anything this particular vehicle seems to like Vortex 95 the best out of all them for economy, performance wise I don't think there is any difference between them.

sednwol · 21-06-2006, 09:08 AM

Don't you get better economy using the '98 ron? Or is that an urban myth?

XR6-VCT-2000 · 21-06-2006, 09:32 AM

Whatever works best for you and your car , or whatever you've had it specifically tuned to run on. ;) .

fordAU · 21-06-2006, 01:03 PM

Quote:

Originally Posted by sednwol

Don't you get better economy using the '98 ron? Or is that an urban myth?

Not really sure, many reckon you do but I can't really say.
I drive pretty sedately being an old codger, should take it out and give it a bootfull, give it a canning, on the track offcourse. :voldar02:

SLY 68U · 21-06-2006, 05:45 PM

Ive got an AUII XR8 220. I've always run vortex 95 and its never missed a beat.
Ran vortex 95 at Eastern Creek and ran a 14.607. Only mod is SS CAI