HOT ROD CAMS HELP!

FIRE IT UP

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Jan 10, 2009
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I've had my hot rod cams installed for about a year and a half now, and have consistently had the same problem of hanging rpms. It has come to my attention recently that it could be a vacuum line problem, i.e. there could be a knicked line in there somewhere that's causing the engine to breathe improperly hang the rpms when the engine slows from a higher rpm to a lower one.
Can anyone help me identify how many lines there are or which it may be that's causing the problem or even how to identify a line failure so I can do the work myself?

Any help would be much appreciated:hail2:
 
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Sounds like an IAC problem

Sounds like an IAC problem to me. What have you done to diagnose this? Have you performed the basic IAC function tests? Have you altered the throttle body set screw? Do you have an ODB2 monitor/scanner?

Look at post #3.
http://www.stangnet.com/mustang-forums/810729-starts-but-dies-idle-help.html

Hanging idle is frequently a bad IAC or bad TPS. But with hot cams, this will reduce the engine vacuum. The IAC with the black vent needs engine vacuum to work. It may be possible that the vacuum is so low as to prevent it from working. In that case, consider switching to a later model IAC without the vent (2001+). However, it is way too soon to make that call.
 
FIRE IT UP:

If the engine has always done this since the cams and tune were installed then it is related to the tune. Your tuner should review the dashpot functions and scalars. If the hanging idle is a recent problem then you are correct to start hunting for a hardware problem.

I suggest that you call your tuner, collect a couple of datalogs that capture the hanging idle problem, and your tuner can e-mail you a modified tune to test. It may take a few datalog/test tune attempts before you get exactly what you want.

Chris