Originally posted by roger blose:
...and I feel that the ignition and fuel are where they need to be.
We have dyno proof and OBD-II plots that prove otherwise... The IMRC stuck open MIL may not illuminate right away, but it will if the linkage is stuck open for two full drive cycles IIRC. If it doesn't, you might want to check the wiring running to the IMRC as your problem source. If the IMRC monitoring circuit can't be completed, the ECU won't notice that they're pinned open, hence no MIL.
BTW, the kick you feel around the same RPM isn't the same as when the IMRC's open... since the injector is in one port only, it normally gets a certain speed of air passing by it at lower RPMs which create the proper air/fuel mix. Pinning the secondaries "steals" some of that air into the secondary port (separate from the primary runner all the way into the cylinder), which slows the primary runner air and creates a poor burn mixture. Without a way to add more fuel pressure, longer pulse width, or higher speed air, what you're fealing at around 3500 RPMs is the air speed finally reaching the point where you're getting a good burn mixture as well as the timing bump from the ECU "expecting" the IMRC opening point.
