29 Aug

While it’s been quiet, things have been happening, and because it’s too hot and humid to be driving the car, you get an update.

To make a long story short, the premature rev-limiting may be solved. The problem is/was that under full-throttle acceleration, sometimes the car would reach redline and sometimes MAP would drop off about 300-500 short of redline. It turns out that the problem is intermittent, which really messes up testing if you don’t realize that! You do a run and see a problem, so you make a change and do another drive. The problem is gone, so you figure you found the trouble and that it’s fixed, only it isn’t. Change the wastegate, it’s fixed, no wait, it isn’t. Change the boost control valve, it’s fixed, no wait, it isn’t. Re-gap the plugs and swap in new ignition coils. Okay, cool, it’s finally fixed… no wait, it isn’t. The only way to deal with this is to make one change at a time and do multiple runs to determine if it’s really fixed or not.

After changing all the obvious things – and somewhat grasping at straws at this point – attention turned to checking less-obvious things such as the rev-limiter function. As an experiment, the rev-limit was increased from 8000 rpm to 8500 rpm. Changing the rev-limiter is the only thing that’s ever had any direct effect on the problem, and beforehand, has never worked right even twice in a row. As of today, three successful runs have been performed without a problem, the engine reaching 8000 rpm without issue. However, more testing is required before drawing any hard conclusions.

I asked the ECU manufacturer if there were any known issues with the rev-limit code, and the somewhat arrogant response was “No, there is not a rev limiter bug*.” That’s a pretty lofty statement; per that logic, anyone reporting a rev-limit bug doesn’t warrant attention because there is no bug – that’s called circular reasoning. To be fair though, maybe the problem is something else, so I can’t be too sure of my own claim until more runs are performed without failure.

* I got a similar reaction when reporting that their manual contained an error regarding how to connect the flex-fuel sensor. Their response: “No one has ever had a problem with this.” The long pause after they realized that their manual was wrong was very satisfying.