Dyno tune but track test A/F not consistent.

[chris2000]

Fitted the S300j and did a tune on WOT on dyno to give 12.5 to 13:1 A/F.

Then road tune for part throttle.

Just before we hit the track we check WOT and it was 12.5 to 13:1 A/f recorded on the PLX-R500.

During the track session we found the car running very heavy and throttle respond is not as good as we wanted and WOT feels heavy. After the track session we check A/F and was shock to find the A/F is now consistently 10:1 to 11:1!!!

What could have cause this?? I'm puzzled..

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S300j fitted in DC2 with B18C5 with Toda C cams.

[Spunkster]

More information, setup, datalogs and calibration.

[CivicVTi]

Check your fuel pressure regulator. SOmetimes they stuck and there is too much pressure in the system and the AF ratios go very rich.