VTEC engaging below set parameters

[Juncura1]

Vehicle: 2000 Honda S2000
ECU: KPRO V4

Hello,

I felt VTEC engaging below the set parameters today so I did a datalog. I've got it set to engage at 4600 rpm/78kpa, but the log is showing engagement at 4600/67kpa which is causing knock. The already logged knock count in the datalog is from a previous event (under the same conditions) before I started recording. Could the tune be corrupted?

[fonzeka]

Your atmospheric pressure reads way low, are you on high altitude?
I'm not sure if the ecu compensates for this and causes VTEC to switch on "earlier" but hopefully the Hondata guys will confirm.

[Juncura1]

Yes. I'm in Denver. The max I see here is 84 kpa. I've setup my tables accordingly and the ecu reads the correct cells (kpa/rpm) so I don't see why it would be engaging VTEC earlier. Hopefully I'll here back.

[Juncura1]

Update:

VTEC seems to be engaging at 4600rpm no matter what kPa I have it set to. I've set it at 78, 88, 98 and 102 all with the same result.

[Spunkster]

Are you uploading to the ECU after making the changes in the calibration?

[Juncura1]

Are you uploading to the ECU after making the changes in the calibration?

Yes I am. I did three tests yesterday. One at 80, 88 and 102. They were all separate tunes and I cleared the ECU before uploaded. They all switched at 68 kPa.

[Juncura1]

Any ideas?

[Spunkster]

As I am working from home, I have no way to test this at this at the moment. We will test when we can.

[Juncura1]

As I am working from home, I have no way to test this at this at the moment. We will test when we can.

No worries. I appreciate the help.

[Spunkster]

I have tested on the bench and cannot find any problem with how it is working. The only possibility is that your calibration is corrupt in some way. I would recommend going to New Calibration and starting with a fresh calibration and see if it works as it should.