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Hi, I have an '84 Corvette and up until recently, it's been running very well although I haven't driven it much in the past year. I took it out the other day and it ran great, the next day, I started it and the idle jumped to 4000 and stayed there. Of course when it happened the first time, Ii shut it down, then I started it again and it keeps doing the same thing. I disconnected the battery to reset the system, but that didn't help. I looked for a stuck cable, but that doesn't seem to be the problem and the butterflies are closed. I disconnected the wires to the top of the injectors one at a time and when the front is connected and back disconnected it still runs high. Vice-versa, it runs lower, or barely runs. I've done various searches and the problems I've seen are similar, but I haven't found one where it's stuck at this high an idle.
I'm looking for any ideas or advice on the problem.
Thank you,
Tom
I'd suspect a large vacuum leak. You can remove the vacuum tube from the left rear corner of the manifold, then block that fitting to eliminate anything on that vacuum circuit as a potential source.
Be sure all of the bolts around the periphery of your intake manifold top plate are tight.
Last edited by Hot Rod Roy; Nov 4, 2019 at 03:33 PM.
From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
Take a look at the TB blade angle and see if they are almost closed. If they are, you may have a rather large vacuum leak. Check TB base gaskets and top plate for starters. Do you get a CEL?
Take a look at the TB blade angle and see if they are almost closed. If they are, you may have a rather large vacuum leak. Check TB base gaskets and top plate for starters. Do you get a CEL?
No, I don't get an engine light and the blades aren't closed completely. I'd guess (not near the car right now) they're about 1/8"-1/4" open or so. Not completely closed..
It ran perfectly 12 hours before this started. I would think I'd see some signs of a vacuum leak before, but I'm not going to argue, just surprised.
I'll give those a try.
Thanks,
Tom
From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
Originally Posted by Hot Rod Roy
That's a problem! Something is holding the blades open. Cruise Control cable, Throttle linkage, TV (Throttle Valve) cable to the trans.
Exactly my point! If they are open that far, you have a mechanical issue with linkage somewhere. Something sounds like it may be binding. blip the throttle a few times at the crossover linkage bar and see if they close more. If so, there is something going on. How many miles are on it?
It was the cruise control. I disconnected the cable and now it works. The end of the cable looked like it was binding and not seated all the way into the little ball chain connector. The ball chain was set on the second ball from the end so the remainder may have interfered with the cable end it causing it to hang up. I'm not sure if that's the whole reason or how it happened, but when I disconnected the chain from the cable, it returned the blades to normal.
It's got 14k on it.
Thanks a million!!
Stuck on high idle problem - '84
