16 Aug

I finally figured out datalogging and boost control, so now it’s down to test drives, datalog reviews, sw changes, and more drives, only this isn’t the best time to be doing that – or just about any other outdoor activity. At around 90 degrees F, the airflow around a open-top car stops making it feel cooler and starts making it feel warmer; at a humid 100+ deg, I’m a slow-roasting turkey in a hot-air oven. Midlana handled it fine, which is a good data point for the cooling system, but it wasn’t any fun for me. It’s frustrating not being able to use my day off to further tuning, but it’s just too miserable to be out driving, especially since it’s not our usual “dry heat.”

The data logs are for fine tuning the ECU control loop for holding commanded boost. It turned out that the parameters I had were too small, restricting the ECU’s ability to maintain a boost setpoint. So that’s getting dialed in, in addition to how MAP dropping off above 7500 rpm, which means finding space to do full throttle pulls in third or forth without scaring people. Typically I run out of room short of that and it’s one reason why I didn’t realize I had the MAP problem in the first place. After finally getting the datalogger sorted, all I needed is one good run to see if it’s solved, which was late in the day, and the anomaly is still present.

Click on the thumbnail and welcome to my world. The more you study the plot the more information will become apparent. The vertical blue line mark where MAP drops off unexpectedly. I’ve looked at just about every engine parameter and haven’t figured out what’s happening first to cause it. The problem is that MAP is a component in just about every engine parameter table, so when MAP drops off, it’s hard to tell if it’s driving all the changes, or one of the changes is driving MAP and it’s just an innocent bystander. This may take a while to figure out. Given that the problem only occurs above 7500, it’s not an issue in 99% of normal driving. It’s when I get out on track that it becomes a bigger deal. If I can’t figure it out on my own I’ll either have to give up and just accept a 7500 rpm limit, or take in to a shop that really knows this ECU.

In a related matter, I got lectured by the ECU manufacturer about their unit being in my street car. Because aftermarket ECUs don’t have government emissions approval, they’re subject to government scrutiny about their product being used on public roads. No problem, I thought, Midlana is 100% road legal and smog-exempt thanks to the SB100 specially-constructed car exemption. Yes it is and no they don’t care; they don’t want to risk appearing to be supporting someone doing something illegal with their product (even if I’m not). So in an odd twist, I’m doing them a favor by not giving their ECU any publicity, so there won’t be any more mention of the manufacturer.