Car A/F totally different on dyno and track

Calibrations for S-Manager - Use all calibrations at your own risk (dyno tuning recommended)
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chris2000
Posts: 56
Joined: Thu Oct 05, 2006 6:35 pm
Location: Asia

Car A/F totally different on dyno and track

Post by chris2000 »

This is on a race dc2 with b18cr 11.5:1 with toda cams.

The car was tuned on dynojet to 13-12.8:1 A/F on dyno with water temp above 81'c.

1st test on track showed that water temp was hovering just below 81'c. about 79-80'c. And A/F was like 11.8-12.2:1. Then noted water compensation shows add over 20% fuel at 75'c.

So when back to dyno to touch up a/f further and try using 0% compensation at 75'c. On dyno it shows that it work and a/f consistent.

back to track for testing, water temp throughout datalogs shows water temp was 79.7'c consistent. And a/f once again drop to 12-12.2:1 instead of 13-12.8:1 that we set on dyno.

Could this be low water temp problem??? But even i set 0 compensation at 75'c and 81'c will the ECU some how still override and add fuel to a cool engine?

I'm now thinking of changing to a higher temp themostat but wanted to get some idea/suggestion from here before burning more money on parts, dyno time and track fee testing...



:cry:
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Hondata
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Post by Hondata »

Always use a stock thermostat. Post your calibration. It could be that the temp compensations are not correct.
Hondata
chris2000
Posts: 56
Joined: Thu Oct 05, 2006 6:35 pm
Location: Asia

Post by chris2000 »

but i have already set the water compensation at 75'c and 81'c to 0% compensation.

Anyway, i have change the thermostat now and will try to get the calibration up tomorrow.

thanks.
newsoltsc
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Joined: Fri Oct 09, 2009 11:49 am
Location: Bay Area, CA

Post by newsoltsc »

The conditions at the dyno are different then at the track.

Your afs will never be the same once you are off the dyno.
-Jose
blackek4
Posts: 40
Joined: Sun Jan 17, 2010 12:06 pm

Post by blackek4 »

take a look at your IAT compensation table. that might be your problem, the intake temperatures are very diferent in the dyno and on the track/road.
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