Big cam hesitation only when cold

Tuning a 2010 camaro with a 525 HP GM Performance crate engine transplanted into it. I don't know the complete engine specs, but it seems to be mostly the same engine as stock but with a much bigger cam.


During the first 5 minutes after a cold start the car runs poorly at part throttle. It hesitates on throttle tip-in and bucks lightly during steady cruise anywhere below 3000 rpm. It feels like a lean misfire and/or it needs more timing. Full throttle it pulls like an animal.

Car runs great at full throttle and runs good at part throttle when warmed up.

Car has long tube headers and an aftermarket air intake tube.


I'm looking for suggestions for things to look at in the tune to fix the cold hesitation.

Tune file attached.

Try loading the stock Final minimum air flow table then multiplying it by .75 and let us know if that makes a difference.

Quote:

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Originally Posted by Mez

Try loading the stock Final minimum air flow table then multiplying it by .75 and let us know if that makes a difference.

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So reduce the final airflow minimum to 25% lower than stock? I don't really understand the logic of that, but I'll give it a try when I get back to the shop tomorrow.


I don't have access to the car right now, but it occurred to me that becasuse the hesitation goes away with rising coolant temperature, perhaps I should try adjusting the injector timing vs. ECT table because to the larger than stock cam. Any other suggestions?

Thanks.

It should tell you if your are on the right track or not.

Check your spark advance. Cat light off spark and piston slap spark tables.