My dealer has finally received v38, and I am scheduled for the install. The Service Advisor states v38 corrects my Yo-Yo problems - however recommends I drop from my Sunoco Ultra 94 Octane to 89 Octane for my Cold Start Promblem. Can he be for real???

 

Dunno. I've seen that advice before, though. High octane gas burns slower than low octane gas, so lower octane gas is to some degree quicker to light off. How much so is hard to say.

I'd be concerned about preignition with low octane gas, though. You can do a lot of damage to an engine that way.

 

This may not be addressing your concern, but I thought it was an interesting letter I saw on a German MINI web site about octane ratings.

 

Yeah, for real, dude!......It works..... 93 or 94 is too rich for the MINI.....89 works fine!.....I alternate tanks between 89 and 93 and have had no further problems! Try it - what's to loose except a problem, right>?

Motor has a knock sensor to compensate anyway, so ........go for it!
I heard no form of knocking or detonation of any kind.:smile:

 

I have had excellent results with Citgo 93 octane gasoline. My '04 MCS (9/03 build) with version 36 runs like a champ and starts the first time EVERY TIME with a cold engine and the idle is smooth as silk.

Whenever I switch back to either Mobil or Chevron 93 gasolines, the idle after a cold engine startup is rougher and unstable. The version 36 algorithms really seem to like and get along very well with Citgo 93 formulation.

Today the car started perfectly smooth with a cold engine. Ambient temperature at the time of start up was around 89F and 95% relative humidity.


Couldn't be happier!:smile:

 

Is there a performance loss from such a low octane?

 

The MINI's computer automatically adjusts the engine/combustion process when lower than recommended octane gasoline is used. You will not experience knocking, etc.

However, you may feel a very slight decrease in power, but not extremely noticeable.


Some MCS owners in our local club currently run their cars in either 87 or 89 octane fuel with no problems for regular street driving and switch to 93 when they hit the track for autocrossing.


Before switching to lower octane fuels, I encourage everyone to try out a tankful of Citgo 93 Octane gasoline. It has made a TREMENDOUS difference in my MCS and I don't doubt it will do so for yours as well.

 

There is another thread on this subject you may find interesting:


https://www.northamericanmotoring.co...ad.php?t=28423

Cheers,
Jack

 

I had the same experience with Mobil. I generally use Amoco or BP 93 without any problems. One time I filled with Mobil and for the entire tank I had cold-start issues. Needless to say, I stay with Amoco until I'm forced by availability to something else.

 

I must admit that anyone with ECUs that tune for better A/F ratio will be shooting themselves in the foot (feet?) because the lower the octane rating, the less aggressive the fuel mapping will be.

I know this is tangential, but still to spend money on ANY mods and then make them useless/more dangerous (like reduction pulleys) by running lower octane fuel is just ridiculous. I have had two cold start stalls in almost a year, using almost exclusilvely Citgo 93. FWIW anyway...

Marty

 

My SA suggested I fill it up a couple times with lower octane. 89 to be precise. I don't know if I am just imagining it or what, but I think it runs better on the lower octane. The cold start problem goes away, I know that for sure.