Superchip 1715 mode questions 2003 F250 V10 4x4
 

I have a new 2003 F250 V10 4x4 and I have been running the 87 octane mode for several days. I do like the mode. Engine is smooth and the trans has a bit more shift pressure although it is a bit lacking for power.
Today, I switched to performance mode. I did notice quite a bit more power and tighter transmission. The engine has a bit more vibration to it. I also noticed that if in park and I rev the engine, there is a bit of popping coming from the exhaust as the engine idles back. This does not exist at idle or when driving, only when I rev the engine and let it idle back. I put back the economy mode and heard the same thing.

Questions:

1. I mixed 1/4 (~9 gals) tank of 87 octane with 3/4 (~20.5 gals) tank of 93 octane and ran for about 14 miles prior to changing to performance mode. Aggregate octane should be about 91-92 if my calculations are correct. This should prevent ping. Am I thinking right? Normally I will fill with 93 but this is the first tank prior to changing modes.

2. Is it normal for the engine to run a bit more rough in performance mode (possibly due to advanced timing and increased air in air/fuel mixture)?

3. What is the popping from the exhaust? I hear a similar thing on high performanace vehicles such as the Roush Stage 3 Mustang. Why is it present in both modes? I have not yet confirmed that it is there in stock mode.

4. The engine has more of a rumbling sound in performance mode. Is this normal? What causes this to happen?

5. Since the computer is now freshly loaded with code, will it take time for the computer to adjust to my driving habits?

Thanks for your help.

Craig
:-tap

Any time you change the tune in the vehicle you need to give it several key cycles and a hundred miles or so for the idle to be relearned by the computer.

We've found that mixing octane typically does not give the octane results you expect and recommend that you run 100% premium in order to avoid engine ping.

To question #2, run 100% premium and give it 100 miles.

The exhaust note change is due to the leaner fuel mixture and timing change. Perfectly normal.

Thanks for the reply Ken. I have run about 60 miles with the mixed fuel so I am going to fill up again. I am not seeing any ping issues so far but the fill today should pretty much round out the tank to 92-93 octane. I am trying to get to 100% premium.

The engine seems to be getting smoother now but every so often, it is rough again. I thought that it took some time to relearn it parameters so thanks for confirming that for me.

Additionally, after speaking with the guys at Roush Performance, they told me that the popping or puff puff from the exhaust on idle back is the air pump in the emissions system and is perfectly normal. I had thought that I heard it on the Roush Mustangs and they confirmed it.

Craig