chines1 posted:@Meade you have an OBD-II diagnostics port, which can be scanned with a common code reader. Most auto parts stores have these and let you use them for free. You will always have a secondary o2 code and a data link code, but note all of the codes and I can reference exactly what they are.
4500RPM is the cutoff point that the motor defaults to if you do not have a speed signal, so a broken or disconnected speedo cabe, a slipping dust cap or a failed speed sensor will cause this. There are other faults that will cause an early rev limit, but they are usually down around 3500RPM, such as a bad VVT solenoid or an errant throttle pedal signal. Normal redline and hard cutout for the motor is 6800RPM, just FYI
My MAF sensor I believe was cutting in/out or missing/ bucking action somewhere around 4K.
We cleaned it and the K&N and we ODB linked it to a laptop and went for a drive and found the MAF was the culprit.
We proved it as it disappeared with the MAF installed.
P.S. The K&N one time was dirty as well as the MAF and causing it to have this symptom. I think this should be cleaned with each oil change IMO.