Epoxy Filled Ported TB? Check This.
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iTrader: (11)
Joined: Mar 2002
Posts: 12,604
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From: East Central Florida
Epoxy Filled Ported TB? Check This. Been chasing some cold start and surging problems ever
since the cam swap. Seemed like nothing I did, with the
running and startup airflow values, had any real effect.
Yesterday I observed that the Desired Airflow in HPTuners
logs was way more than the actuals. So I was asking and
not getting. I thinks to meself, "maybe time to drill more of
a hole in the epoxy".
Well, hell yeah. Check the chart:
1/4" hole limited the max airflow to about 11 g/sec. This is
where I am trying to idle, roughly. Looking for more to start
cold, no dice. Opening it up to 3/8" made the IAC regain full
range of airflow. Back in the day, people were saying 3/16"
would do.
It wasn't much of a problem with the stock cam but the
224 needs more.
If you need more air and can't get it, the PCM just keeps
commanding is higher and higher, with no or little result,
then has to ramp back down if it ever gets there. That's
a good way to get low frequency surging. Car used to die
the first time I put the A/C on; now it doesn't, and starts
like stock again cold.
If you fill it, drill it - and drill it good.
since the cam swap. Seemed like nothing I did, with the
running and startup airflow values, had any real effect.
Yesterday I observed that the Desired Airflow in HPTuners
logs was way more than the actuals. So I was asking and
not getting. I thinks to meself, "maybe time to drill more of
a hole in the epoxy".
Well, hell yeah. Check the chart:
1/4" hole limited the max airflow to about 11 g/sec. This is
where I am trying to idle, roughly. Looking for more to start
cold, no dice. Opening it up to 3/8" made the IAC regain full
range of airflow. Back in the day, people were saying 3/16"
would do.
It wasn't much of a problem with the stock cam but the
224 needs more.
If you need more air and can't get it, the PCM just keeps
commanding is higher and higher, with no or little result,
then has to ramp back down if it ever gets there. That's
a good way to get low frequency surging. Car used to die
the first time I put the A/C on; now it doesn't, and starts
like stock again cold.
If you fill it, drill it - and drill it good.
