A lot of threads touching upon these issues, but I have two specific questions:

(a) I know the MINI uses its knock sensor to pull timing if it detects knocking due to low octane fuel. Does the MINI remember this new retarded timing everytime the car is started up?

(I ask because if it doesn't and it resets upon every start up, then I would guess the engine would be knocking upon every startup, which would be bad, no?)

(b) If the MINI keeps this new timing upon every startup (to prevent knocking) and one switches back to a higher octane, how does the ECU know that it should revert to the timing appropriate for the higher octane?

(Note: Let's please not debate low octane vs high octane----there're other threads for that I just wish to understand what the ECU is doing. Thanks!)

 

the ecu only retards timing when it notices knocking. you can actually run a lowergrade octane with it out the ecu retarding the timing if there is no knock.

the ecu does not remember this it only adjusts to what it detects. so if its set back because you used 87 as soon as the knock goes away when you put in 91 then it will advance the timing back

 

Exactly! The ECU does not store a previously encountered knock but monitors the engine in real time and adjusts accordingly.

 

Hmmm ... so the engine detects the knocking, pulls timing till knocking disappears. Since the knocking is now gone you say it will then advance the timing back until it knocks again (?) and then will pull back the timing once more? Is that right?

 

As I understand it, the system monitors, and adjusts, constantly, or as Suzanne's Chili said so succinctly, "in real time".
Picture driving on a hilly road, and trying to maintain a steady speed; You increase and decrease the throttle according to the road conditions and grade. The ECU retards and advances the timing in order to maintain, for lack of a better way of putting it, optimum efficiency.
Hope this helps a little.

 

yes thats is correct

 

OK, I have to admit that my questions arose from the discussions about 87 vs 91 octane. If what you folks are saying is accurate, then I would think that putting in the lower octane fuel is clearly a bad thing to do.

If the ECU is always trying to push the timing to an optimal level then getting knocking then pulling back the timing, then pushing it forward then getting knocking, etc, etc, etc. I would imagine that the engine may go through a lot of knock! (Something that I think everyone agrees is bad.)

(So, I wonder why some folks argue so strongly that "the ECU will pull the timing anyway, so it is OK to put 87 octane." Yes it is pulling the timing, but it is doing that a lot of times every time the engine knocks----not a good thing, right? )

Thanks for the input folks.

 

Hard to read the grey text, but yes, pulling timing is not a good thing. Besides dragging the engine out of it's optimal performance range, most new vehicles (I think that includes MINIs) make the fuel mixture richer to help compensate, and Whups!, there goes the mileage. Also not good at 5 bucks a gallon.

 

Thanks, AM. Yeah, I was trying to avoid making judgements about performance and mileage ... just wanted to understand what's going on physically. The arguments that the ECU will pull the timing and so things will be OK just didn't make sense. For the engine to know to pull the timing the engine has to be knocking in the first place---which is bad.

 

Put it in context, as well. MINIUSA has said that 91 OCT is not required on the 07 & up Coopers, because the PSA/BMW VVT engine will perform well either way. I do not believe the Cooper owners manual calls for 91 AKI as a requirement anymore (not sure though).

But on the UK01-06 TRITEC engines, running 87 AKI is likely to kill any $$$ savings in the loss of MPGs.

This being said, everyone I've talked to lately at MOTD, MTTS, MOT, etc, has said they run 91 AKI in their 'S' no matter what. OK, OK, so there was ONE guy that runs 87 and below in his 'S' (which Dyno's at about 115WHP...).

BTW, I've done two 'test runs' when I was in Washington State to judge 87/89/91/93 AKI effects on performance & MPG. I noticed a maximum of 2.1 AveMPG between the two extremes, 87 to 93. And I noted a sluggish pedal response with 89 & 87. So if you're pouring $1000 into pulleys, exhaust, remap... why pour less than 91 in the gas tank?!?

(yes, I know, I turned it into a mileage & performance thread, SORRY! I'll buy you a beer the next time we're at a MINI meet)

 

QandElf: you drive a long ways to do test drives! Hope your visit to our little corner of paradise was a pleasant one.

 

Actually, AM, I was stationed in Washington. First US port my MINI was in after I bought her in Italy. Both my Motoring Crewmates (ie- Kids) were born in Washington. And even though we've since moved on, we're still paid up, card carrying members of PSMINI.

So, yes, I'd say our visit was a good one!

 

Ha ha, no problem. Beer is good.

 

Well said. I have a ScanGauge II in my MINI. I normally do not have it set to display timing, but to see this for myself, I set it to display timing and the ECU is constantly moving the timing all over the place. Of course, the ScanGauge can not show why the timing is moving, only that it is moving.

 

INteresting; thanks! I need to get one of those ...

 

Yes, you do.

If you are not Tracking your car on a routine basis, the Scanguage II provides you with everything you need to monitor your MINI's performance, and even has a built in code reader.

The latest iteration includes 'X-Guage', which allows you to determine Boost dependent on your normal altitude. So it can work effectively as four gauges at about a quarter of the price! Not too shabby!

I will say, however, that it's based upon your OBD II ports output from the ECU, so IF you do track your beast, or you just need the accuracy of Mechanical input, then this is probably a nice add-on, but won't satisfy the 'need' .