Feb 092012
 
91octdatalog

Recently we have been getting more and more customers with poorly runing cars, or check engine codes for super knock.   A large source of these customers are in California or where 91oct fuel is the highest they can get at the pump. In any turbocharged or supercharged engine, octane is very important for performance and for keeping knock/detonation at bay.  This article isn’t about knock or what it is, or why its bad, you can find out about this many places on the web.  This article is to show you how bad your Mini R56 turbo will run when its on 91octane fuel.

This all started a couple years back when customers would call or even complain about their MINI loosing power, has hicupps, or just overall not smooth running engines. Besides all the normal MINI gremlins, we started to see a trend in customers calling. Shortly after that, we came out with the AccessPORT, which allowed us to see much deeper into the problem.

Most likely people that are “feeling” a loss in performance over time are either:

  • Most likely are not running an AccessPORT in 91 oct areas.
  • Are seeing issues from carbon build up
  • BOV’s have ripped diaphragms

Knock Knock……

The first reason is important because I have seen the stock tunes on 91 octane cars in California run very dangerous. Like ignition timing constantly being retard 5 degrees from what the map is calling for. That along with how lean the car is setup to run, its not very good/safe under full throttle. The next problem is that the ECU is constantly testing the octane in the fuel by adding timing until it knocks, then pulls it back. For normal cruising around town this is ok, but for full throttle power runs, this is not.

On the AP, we tell the ECU to start out with less timing so its consistent all the time, and overall makes for a better running more powerful car. Add to that we run a richer safer Air Fuel Ratio under full throttle. This is the other thing that causes MAJOR issues with knock. In stock form MINI programmed the engine to run super lean under full throttle. Its great for fuel economy, but BAD for power and durability under full throttle. This is how engines blow up, knock atr 18psi of boost at 6000 RPM is NOT GOOD!

I truely feel this is one of the many reasons why we are starting to see more and more engine failures in areas with 91 octane fuel.

Proof is in the Datalogs

You can see the left graph is showing the stock ECU on 91 octane. The right is showing ALTA stage 1. This is on a JCW BTW.

We had many customers log their car running the stock maps and then compared it to our map.  What signs you should be looking at is ignition timing, Air Fuel Ratio and Boost. You can see how the igntion timing is all over the place. It should be a nice smooth number increasing as it goes to redline.  On the stock mapping you can see where it pulls timing all over the place and isn’t consistent at all. The second thing is the Air Fuel ratio. Under high load you can see how lean it is. Typically a turbo engine runs between 12-10.5 AFR. Leaner than 12.5 is dangerous as it can lead to knock and higher EGT’s. Because the MINI is a direct injection engine, it can get away with this, kind of……

Don’t Reset Your ECU!

I also hear customers (without AccessPORTs) saying “My car learned around my aftermarket parts I installed, so I have to reset my ECU all the time”. This maybe the case, but in fact, its just your car detuning itself to be safe and not blow up.  For instance on a 91 oct California car, after an ECU reset it may feel faster (because of the higher timing) but over time the ECU retards the timing everywhere to keep it safe.  Resetting the ECU is bad because it will constantly have to deal with knock and constantly be fighting this. It is much safer if you do not have an AccessPORT, to just leave it alone!

 

Besides our ALTA Tunes making more HP, they are much safer and more consistent power than the stock tune.

The ALTA AccessPORT takes care this problem because we actually tuned the ECU for full throttle. We didn’t care about fuel economy under full throttle, we cared about horsepower, and safety of the engine. The graph above shows a lot of things. It shows the engine is running safer with more boost, its making more HP, and accelerates faster. It may sound like a scare tactic to get customers to buy an AccessPORT, but if you value your MINI and you live where 91 octane is the highest octane fuel you can get, consider your self scared.

 Posted by on February 9, 2012 About Your Car, Dyno Test & Tune, MINI Only

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