4AGZE Power loss at high RPM

[z0ton]

I recall this being covered in the past but I can't seem to find the threads, what is the fix for the drop off at about 5500 rpm?

There are times when there is no sudden power loss at all but most of the time its really noticeable.

I remember discussion around the knock sensor?

[MAC_HATER]

if the knock sensor hears something it doesn't like at the top end and pulls timing it would explain why it falls flat on its face there, My corona will do that from time to time, but that's cause its *actually* pinging and the sensor is doing its job, I just need to run 98 as intended and it is fine, but for you if you're already running good fuel, maybe try a known good spare sensor if you can get one?

[Pelo]

Could it be the supercharger belt slipping?

[~SlideWays~]

You could try pulling a little bit of IGN timing via the CAS. That worked for me with one of my old MAP 4agze's, it flew passed 5500 and went better than ever (butt dyno).

Other than that, you could try source a new knock sensor, I don't think they can be bought new anymore though.

It's not the supercharger itself, it'll happen on a turbo converted MAP ecu'd 4agze dead on 5500rpm as well, so this points to knock sensor as well. But if it's detonating, retarding timing will held.

Or run 98 and some octane booster in every tank.