lean after dyno tune.

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So I got my car tuned yesterday on the dyno. A/F was perfect while making pulls on the dyno. On the way home I tried to make a quick 3-4 pull but had to back out as a/f was high 12's lox 13's. There was a considerable amount of wheel spin on the dyno which required someone in the trunk and even then it still spun a tad. Is it possible this tire spin could have effected the ecm calculated load which in turn is throwing my tune off under a real world load.?

This was a mustang dyno BTW. Datalogged this morning and injectors are at 70% and pumps are at 74% so I am no where near maxed on anything including the maf.

Tvs 3.0/4#
E85

 

[LGHTEMUP]

check alternator or charging system..

 

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I always log that when datalogging. 13.0-13.4. It is not a voltage issue, would have found that when logging.

 

[LGHTEMUP]

looks like you have a stock alternator and those can not keep up if you have a upgraded fuel system and any other mods...you should see over 14.0 all the time to run an aftermarket blower and fuel system...and what kind of battery that comes into play too..

 

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Its never been in the 14's. Not even when stock. Has a 3.2 metco alternator pulley on it to keep it from over spinning and making 14 volts. 13+ volts is perfectly healthy under load. @ 75% duty cycle with perfect rail pressure it is clear it is not a voltage issue.