Welcome to the Corvette Forums at the Corvette Action Center!

start up idle

L

LarryK 87

Guest
have had this going on now for about a month. when the engine is first started, rpm goes to 1800,and holds there for about 3 seconds, then drops back to around 900. does this hot or cold.

any ideas what could be causing this?
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Got a VAC leak

Somewhere.. time to strat lookin @ vac hoses!



Vig!
 
1

1DOWN6TOGO

Guest
does this for my '77 as well when i put her in park
may be completely unrelated, but thought i would ask
thought at first idle was too high, but it idles beautiful when runnin' in drive

any ideas?
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Completely different

Your 77 is a CARB.. the premise might be similar.. but the control devices are different.


Vig!
 
1

1DOWN6TOGO

Guest
i should have stated that all differently.
i mean, i know i have a carb! :J
what i meant, was i am wondering if y'all knew what causes my problem. i just posted it there because the symptoms were the same, and it was convenient
it's not a big deal to me. hasn't given me any trouble yet.
thanks Vig

sam
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Sam

I knew YOU knew you had a carb...the statement was intended for others ...not as savvy!


So a VAC leak will raise the idle by some amount...I would start checking lines in yours too!...and I know it's a train wreck under the hood of Later C-3's...

I hose at a time!


Vig!
 
L

LarryK 87

Guest
should have posted this with the original post, just missed it, all hoses ( Vac ) have been replaced ( underhood ) with new stock, car is also missing the Vacuum tank ( this line i capped off ). on a few occasions ( after having the ECM in Diag mode ), and IAC, TPS re-adjusted, engine starts perfectly RPM at start up is ~1000. as would be expected, it almost appears as the IAC is slowly moving its self to progressivly higher settings for start up, I did how ever try putting it into diag mode ( did not disconnect the IAC as you would when adjusting minimum idle ), key off, Remove diag plug, start engine, same effect, high initial idle, then settles down, ( i defeat this most of the time by starting the engine as if it is in flodded mode ) causes the engine to stumble at first, but it also allows the oil pressure to climb before revs climb to 1500+

Side note, i have not replaced the hard plastic Vac lines, as they all appear to be in good shape, ( or is that a bad assumption on my part)
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Assumption

= make a ass outa U & ME!


Vig!
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Parts/Accessories:

Vetteskins

Advertise with the Corvette Action Center!

Double Your Chances!

Partners

Top Bottom