I managed to find the time to upload some documents and original ecu files to the forums. Finding time for car tuning is harder. Getting home from work at 7pm and trying to tune your car and not annoy your wife is a hard thing to do. Not to mention there seems to be endless work to do on the house and the other cars I don’t want to tune. But, I did find time to make an exciting favicon for the website. 😛
So far there hasn’t been much activity in the forums. I’m hoping that once I am able to post some results from my initial tuning in the forums that will stimulate some interest. Once we have some interest in the forums it will be easier to discuss some of the advanced tuning features of the ME7 in an informal stream of consciousness sort of way. If you want to talk about something in particular, just start a forum thread and I will start answering questions as soon as I can.
What time I was able to spend on tuning in the last week, went to fixing some bugs in my data logger software and playing around with rescaling the MAF, fuel injectors, and injector latency correctly. My goal is to rescale the MAF and injectors to physically correct values, and not just scale them relative to each other. To achieve correct scaling I am going to remove my larger MAF housing and reinstall my stock MAF housing with known scaling and flow characteristics. Once I have done that I will be able to scale the injectors relative to my known MAF. Then once the injectors are scaled correctly, I will reinstall my larger MAF housing and begin scaling that until it behaves correctly.
The way I am testing to my changes to the fuel injector scaling, and fuel injector correction is by logging the short term and long term fuel trims. The long term fuel trims give you great feedback on what the engine computer believes the idle additive offset and part throttle multiplicative scaling are. The idle additive offset long term fuel trim is essentially the discrepancy between the injector latency values in the ecu and the actual injector latency. You can use it to determine if you need to increase or decrease the latency values in the ecu. The part throttle multiplicative scaling long term fuel trim is the discrepancy between the flow rate of the injector in the ecu, and the actual flow rate of the injector. This you can use to determine if you need to increase of decrease the scaling of your load to injection time conversion constant in the ecu.
If you want to get crazy with some spread sheets, then you can log your short term fuel trim and plot it against your injection time. Then you would need to do a best fit line through your data set. The difference between that best fit line through your logged data and the ideal line with zero correction can tell you how to adjust injector latency and scaling. If the line starts above or below the ideal line, that will tell you how to adjust your latency. The slope of the line will tell you how to adjust your injector scaling.
It all sounds simple! But when you factor in software bugs, potential vacuum leaks in the motor, problems with fuel atomization at idle, problems with injection time accuracy when using short injection duration at idle, it quickly becomes a moving target taking much longer than you expected. But in the end it will hopefully all be worth it when the tuning start to focus purely on the performance side.