Smokes like a Duramax at WOT

[BiggFoot]

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[QUICRNU]

Originally Posted by dreksnot

Perhaps it's your tune's Power Enrichment. When you nail the throttle, your car goes from stoichiometric AFR of 14.7:1 to whatever your PE table is set to, like 10.5 to 11.5 AFR (which many tuners use for FI applications).

Pictures below:
<> First table is the Stock GM LS3
<> Second table is a typical Supercharged Power Enrichment table (a tuner may use)

These tables are in EQ ratio, which is the inverse of lambda, which is the percentage of Stoich, so if you're looking at 2,000rpm on the Supercharged PE table, the EQ value is 1.25, which is 0.80lambda (1/1.25), which is 11.76AFR (0.80*14.7). So, depending on your PE settings, your PE table could be very rich at low RPMs. Just some food for thought - ask your tuner where it's set. I believe if it's too rich down low, you're dumping fuel into the motor and you're blowing smoke.

But, depending on other parameters in the tune, it could be dumping way more fuel (like where the MAF/VE tables are set - if they're heavy, then PE will be more than commanded).

Wouldn't 11.40 AFR seem rich, or is that where the Whipple likes to be?

[cc-rider]

Yes. Any forced induction needs 11.5ish afr. Naturally aspirated can be up in the 12's.

[MudderFinger]

Originally Posted by dreksnot

Perhaps it's your tune's Power Enrichment. When you nail the throttle, your car goes from stoichiometric AFR of 14.7:1 to whatever your PE table is set to, like 10.5 to 11.5 AFR (which many tuners use for FI applications).

Pictures below:
<> First table is the Stock GM LS3
<> Second table is a typical Supercharged Power Enrichment table (a tuner may use)

These tables are in EQ ratio, which is the inverse of lambda, which is the percentage of Stoich, so if you're looking at 2,000rpm on the Supercharged PE table, the EQ value is 1.25, which is 0.80lambda (1/1.25), which is 11.76AFR (0.80*14.7). So, depending on your PE settings, your PE table could be very rich at low RPMs. Just some food for thought - ask your tuner where it's set. I believe if it's too rich down low, you're dumping fuel into the motor and you're blowing smoke.

But, depending on other parameters in the tune, it could be dumping way more fuel (like where the MAF/VE tables are set - if they're heavy, then PE will be more than commanded).

The PE ramp in rate setting could also be too high. To the OP, the hose sounds like it may have been leaking vacuum, if so the computer would try to add additional fuel to make up for the leanness the leak caused.