i just swapped a 96 ls head onto my friends 90 ls... his car ran fine before the head swap and threw no codes... after finishing we started the car... it started right up but the tach jumped to 5000 rpms!!... i triple checked everything... all sensors connected, no vacuum leaks, vacuum lines connected correctly, not throwing any codes when running... im gonna try a new intake manifold gasket tomorrow... does anyone else have any ideas??

 

check the throttlecable, its probably too tight, i just got through putting pistons in my car and my idle was at 2500 the throttle was too tight, so mabe your throttle was to tight, thats what it sounds like to me

 

spray brake cleaner around the gaskets and see if they are leaking.

without an intake connected to your throttble body put your hand over the throttle body so that the engine can't get any air... if it keeps running you definatly have a gasket problem...

have you looked to see that the throttle plate isn't physically stuck open partially as mentioned above?

 

yeah i loosened the throttle cable until it was just hanging so thats not it... also tried messing with the idle adjuster screw but didnt do a thing... ill try your throttle body method though... thanks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheOne &raquo;</TD></TR><TR><TD CLASS="quote">check the throttlecable, its probably too tight, i just got through putting pistons in my car and my idle was at 2500 the throttle was too tight, so mabe your throttle was to tight, thats what it sounds like to me</TD></TR></TABLE>

good info

nice icon too "TheOne"

 

hey...has anyone told you, 5000rpms is a little high for idling?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by integraL &raquo;</TD></TR><TR><TD CLASS="quote">hey...has anyone told you, 5000rpms is a little high for idling?</TD></TR></TABLE>

Yeah thanks for helping

I would definately check the throttle cable over all others. Check the pulley and other things. Easy way to make sure is to run it without the intake and see if the butterfly is partially open.

 

yeah i will check it without the intake before i put the new gasket on... i doubt it is the plate though because like i said everything was fine before the swap

 

it was the i/m gasket... car runs super smooth now