Bimmer Challenge Round 2: Buttonwillow Raceway Park CW13
With the tune and downpipes removed, I thought our drivetrain malfunction/limp mode issues were a part of history. Especially after the test and tune day at Streets of Willow Springs where the car was ran hard and ran flawlessly, the drivetrain malfunction bug bites once again. The first lap out I was able to lay a 1:54 lap (quite a bit of pace off of my initial 1:52 lap), however it was a decent time to go out and get a feel for the tires and the new alignment. The car was gridded P7 out of the session of 30 or so and I had set out to claim a faster lap. I ran a 70% pace warm up lap to get temps up to speed, and set a near perfect exit out of the first corner and jammed down the front straight away. We had great top speed leading into turn one and by turn 4-5 the predictive lap time showed a low 1:51 on the AIM solo lap timer. I had just surpassed the halfway mark of the lap, exited riverside with good mid and exit speed, and ran full throttle into Phil Hill. Under heavy braking, and trailing right about to crest the apex, the DRIVETRAIN MALFUNCTION STRIKES AGAIN/ Cutting all boost, limiting the car to 4,000rpm and unloading the car quite violently which I was luckily able to save and keep the car on track. I limped it off and let as many people by as possible with my limited speed (I apologize to any other drivers that may have gotten held up by this), and pulled directly into the pits. I key cycled the car, no hard codes were stored, and once I fired it up, the drivetrain malfunction is gone. I checked the coolant levels and they were fine, and let the car cool before the next session. We had one more session to make it count for the competition. 3rd session came after lunch with a bit more ambient temp as well as drastically higher track temps. According the GPS data the car was seeing about 6mph less top speed at the front straight with the same corner exit speed leading up to it and 100% throttle. This meant power/timing was being pulled once again. This leads me to believe the issue lies in heat, intake air temperatures to be specific. Keep in mind this is my best hypothesis as it makes sense for the ECU to engage its failsafes and pull timing especially once it sees higher temps being a forced induction engine. One quick idea that can alleviate under hood IATs as well as increase front downforce (believe it or not), would be to add hood ventilation. The battle now is to cut and add an aesthetically pleasing hood vent as that is very important to me (lol).
To my surprise, I have not personally seen many F80/F82 chassis being pushed to extreme limits, which can also contribute to the lesser seen issues that I may be experiencing. That being said. I will be partnering with a good buddy and track going veteran Amir Bentatou, of RS Future. We will be doing a test and tune day, and logging all data through OBD2 to get all readings from GPS, throttle position, brake position, g force, coolant temps, oil temps, IAT temps etc. We will review the data and see exactly at what temp and in what sections this issue is happening it and will narrow it down to gain solid track and data proven results to share with other track going S55 cars/drivers. The 1:54 lap placed us 4th, edged out of podium by a few tenths in (a very competitive where the fastest times were within 1-2 seconds from 1st-4th) Bimmer Challenge, which is where I did not want to be, but hey once again, the car lived, and although frustrating, we will get to the bottom of this and figure out the recipe for a properly working S55 driven under heavy track conditions.
Unfortunately a buddy had a tensioner pulley failure, so I had to pay it forward to a fellow S2K owner (S2K owner myself), and towed him home.
