This morning on the way to work the Emperor felt his usual self (VVT kicking in at 3400 RPM with a solid pull up the rev range) until he got fully warmed up, then he reverted to the off tune style acceleration (VVT hitting at about 4500 RPM and sluggish acceleration.)
Thinking I have another another clue to my troubles, I emailed Steve at Panic at Panic Motorsports:
Saturday I put a new Cam Position Sensor in and now the VVT seems to act right – for the first few miles. Once the car is fully warm the VVT “surge” moves from ~3200 RPM to around 4500 and becomes almost unnoticeable and the car feels out of tune.
Is this warm/cold thing a clue or another red herring? Should I tackle the actuator itself even though it appears to be walking a high wire without a net?
His reply:
mmmmmmmmmmmaybe. There is a temperature sensor on the back of the head, sometimes you can grab on to them and twist (gently) to see it if moves. It shouldn’t. Fishing here, via emails obviously, but always happy to help you fix on your own if possible.
Today after work it seemed like the VVT would kick on at the higher 4500 RPM, but then it would solidly pull to 6000 RPM. I’m waiting now for the motor to cool off enough for me to reach between the firewall and engine to see about those wires. My logical, but ignorant mind, thought for sure he was going to say it must be that actuator because it is so oil pressure dependent and the change is due to the multi-viscosity oil thinning after it heats up. But no.
I still think it is the ACTUATOR, VARIABLE VALVE TIMING Part #BP6D-12-4X0D, but no where near sure enough (remember logical & ignorant from above) to just pull the trigger on one. Let alone know how to change it out. Trouble being that what resides inside that actuator remains a tightly held secret, no wait, I forgot Google, I’ll be back in a couple of hours, wait here.
Miata Top Transitions since 06/25/15: 182