AFR goes rich after track time?

[gslender]

Just rebuilt the 1.6 engine, and after 4 runs on the track I notice the AFR has become very rich across the map.

Check the tune and nothing has changed. The pw are same in early logs and last run, but AFR measured is approaching 1.5 lower.... ie near 11 instead of 12.5 for example. now is idle at just 13 instead of 14.5

I can't see anything that says the ecu has changed, but was wondering if aspects of the running in of the engine can account for that? Engine has done about 400klms before the track day and was running maybe 170kPa boost from a SC. intake temps not crazy high, but normal at around 40.

Would failing spark plugs or Toyota COP be the culprit? Changes to engine advance/retard maybe?

Thoughts?

G

[Sailor]

Plenty of dusty offs?
Try a new air filter

[A.Chen89]

Recalibrate the wideband?

[gslender]

Plenty of dusty offs?
Try a new air filter

Nah, doubt dust is the issue, but you raise a good point. Does air filter restriction impact flow volume but not manifold pressure? Need to think more, but initially I'd think that a restrictive filter would show up as a reduction in MAP sensor, which is then aligned to the ecu tune correctly, but perhaps not ???

Anyway, gives me something to look at....

G

[timk]

Recalibrate the wideband?

+1

A misfire will show as a lean condition, so I doubt it is your coils.

[manga_blue]

Recalibrate the wideband, though it's probably reading more correct now after a good track blasting than it was before.