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Discussion and questions related to the course EFI Tuning Fundamentals
So I been re-watching every lesson thats available to me, and I'm really surprised that I am actually starting to understand some of this stuff. And now that I am starting to, I feel so much more relieved 😌 and confident that I will fully understand all the lessons. That being said.. I ran this in my situation in my head many times but I can't or not can't.. but not yet understanding how kpa is increased but the rpm can stay at a certain rpm.. Hopefully I don't sound to stupid.. Lets say I'm at 30% KPA and rpm is at 3000 rpms. Then I increase my KPA to 40% but rpms are still at 3000.. with increasing the KPA, wouldn't the rpms climb also?? With pressing down on the throttle to increase load or KPA increase both load and rpms at the same time?Or am I over thinking this? Or can you increase the KPA load and bring the rpms back down to 3000?? If anyone can help me understand this a bit more, then I can finally get a better understanding on how to read and find the exact point im at on the fuel tables. I know how to find where I am at, its the KPA load and rpm increase that has me kinda stumped.. Thanks in advanced.
This is happening because the car is being run on a load controlled dyno. So as the throttle is opened (and the Manifold Pressure, measured in kPa increases), the engine produces more torque, but the dyno holds the engine speed (RPM) constant.
You can approximate this when street tuning, but it requires real skill to left-foot brake and keep the RPMs constant. You should not be trying to live-tune unless you are in the passenger seat and someone else is doing the driving. When street tuning, normally you will simply be trying to operate the engine in as many cells as possible, and will examine a data log later to decide on what changes to make. Another good technique, is to drive up steep hills, those require more load at a given RPM that cruising on the flat ground.
Many dyno's are not load controlled, and the engine will accelerate as you increase the throttle -- but for proper EFI tuning, you want to use a load-controlled dyno so you can use all the techniques shown in many of the HPA videos. Any tuning setup (Standalone ECU, or re-flash that allows live tuning) will also speed up the tuning process and really requires that load-controlled dyno to tune the ignition timing.