I don't know if they dealership put premium fuel in it, but I put 89 octane in on my first fill up. That might not be high enough octane, and causing detonation, but I won't know that.
Is this something that the ecu does (i.e. learn driving habits)?
You aren't offending anyone, but please explain how you know that the program is 'pulling timing". Isn't that an assumption on your part?
Actually, it may not be.
MattM, a brief run down on ECM "learning".
What most people talk about when they are talking about an ECM "learning" has to do with fuel trims. There are two types, Long Term Fuel Trims (LTFT) and Short Term Fuel Trims (STFT).
Whenever you reset your ECM (through a programmer, scanner, or unplugging the battery for about 30 minutes) you are resetting your fuel trims to 0. When a fuel trim, Long or Short term, is at 0, it is neither adding or subtracting fuel from the basic fueling table. This means, whatever values you have in your various tables that dictate how much fuel to add (fuel injector tables and Mass Air Flow, or MAF, tables mainly) are spot on and the trim has to do nothing.
Now, if your trim goes into a positive number, this means that whatever you have in your tables is off a little and the trim has to add more fuel to achieve the proper Air to Fuel Ratio (AFR) for those specific conditions...ei RPM, Throttle Position, MAF reading, fuel injector duty cycle, etc. If the number goes negative, then that means the trim is pulling fuel to achieve the proper AFR.
Like I mentioned, there is a Short Term Trim and a Long Term Trim. The STFT is what the ECM is doing RIGHT NOW to adjust fuel. If, for a certain condition the STFT is constantly adding or subtracting fuel, it will re-write the LTFT to the average STFT value for that condition.
So let's say for a certain condition your STFT averages -6. This means it usually is rich in this condition and thus the STFT is pulling about 6% of the commanded fuel to hit 14.7:1 AFR (because for this condition you're just cruising...makes things simpler). So since it's doing that, it writes -6 to the LTFT. Now your LTFT is at -6 and your STFT is at 0 for this condition. Why did the STFT change? Because the LTFT is already pulling the 6% the STFT averaged. Now, there may be times when the LTFT is at -6 and the STFT is at 1 or -1 too but it's average over time should be at 0 once the LTFT cell is learned for that condition.
What's important to know is that the values for the LTFTs and STFTs are cumulative. So if the LTFT is at -6 and the STFT is at -1 then you are pulling 7% fuel at that condition. If LTFT is -6 and STFT is 1 then you are pulling 5% fuel for that condition.
This is how the ECM "learns" not just your driving style but the little nuances of your engine, the environment you're driving in and how the engine is reacting to different conditions.
This is constantly happening and your LTFTs and STFTs are always updating themselves. As a tuner, one thing we do is tune the MAF table to get those LTFTs to learn to 0...or as close to 0 as possible. This means our ECM is loading the proper values to hit the correct AFR target in these conditions within +/-2%
To get a better idea of how all this works, check out these two images I made on closed and open loops in the ECM. This was for a Harley forum but the principle applies here too. This is just a very basic overview on what's going on with our ECMs:
HOWEVER, This learning has nothing to do with spark. This is only fuel. Our ECMs are designed to run our cars optimally on 91 octane or higher fuel. When you do this, you should see no knock and when the ECM sees no or only sporadic unpredictable knock (which is defined as false knock) it runs on a spark advance table called "Good Fuel Spark Table". This is your basic spark table and determines how much spark advance the ECU bases it's spark calculations on. Now, whenever you see knock, false or otherwise, the ECM will pull timing (reducing performance) to try and combat this knock. With False knock, because the knock is usually just there and gone, this timing comes back very quickly. With real knock though, the timing will come back more slowly as knock is reduced. The worse the real knock, the longer it takes the ECM to add it back in.
However, if you have knock consistently, the ECM will switch over to what it calls the "Bad Fuel Spark Table". This table has lower timing across the board. Remember, these Good Fuel and Bad Fuel spark tables are the base spark advance table your ECM uses before adding or subtracting timing for various conditions. Thus if you run on the Bad Fuel Spark table, your timing will always be less than if you're on the Good Fuel Spark table.
Running your car on anything other than 91+ octane will put you on the Bad Spark Table. This is why our engines are "recommended" to run on 91+. If you run on 91+, you get the Good Fuel Spark table and get more performance. If you run on less than 91+, the car isn't going to get damaged but it is going to run on the Bad Fuel Spark Table and the reduced performance that goes along with that.
So if he is running on 89 octane, it may be a safe assumption the ECM is "pulling timing" because it should be running on the Bad Fuel Spark table. This also means just scanning for knock may not tell us anything. If the car is running on the Bad Fuel Spark table and it's lower spark advance numbers to start with, the car may not be seeing any knock...and thus the Bad Fuel Spark Table is giving us the results is should be giving us, no knock when running on fuel with an octane lower than 91. We need to see the spark advance commanded to get an idea of what table his ECM is running on.
I will also add that running on 89 octane is the worst decision you can make. It's more expensive than 87 but gives you 0 performance benefits over 87. Run 87 or 91+...and with the turbo motors you really only want to run 91+.
Dropping your boost to 13 psi though is related to neither of these things. That sounds like your ECM is pulling boost for some reason...or you have some other issue that's causing a loss of boost pressure...though usually that's an all or nothing kind of thing if you're not getting some kind of engine code along with the lower performance.