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Swooshski
User
Nov 20, 2006, 10:01 AM
Post #1 of 7
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94 S-10 high idle
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My son's 94 S-10 (little bitty 4 cyl engine, I forget the size) has all of a sudden developed a very high idle. I checked all hoses etc and they look to be in place and making good seals with no vaccum type leaks. I even tried adjusting the idle via the throttle cable adjusting screw ... but even with it backed off all the way the engine still idles very high (put it back where it was). And the engine seems to bog down when the clutch is let out.
I also noticed a rattle in the catalytic converter. Could this be causing it? I've never had a converter go out so I don't know what kind of impact that will have on the engine.
Man, first the buick ... and now this! I hope my F-250 holds together until I can get these 2 back on the road!
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 20, 2006, 3:13 PM
Post #2 of 7
(4765 views)
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Re: 94 S-10 high idle
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If no check engine light I still would suspect vacuum leaks(s). Carb cleaner sprayed at spots possible can change idle and it shouldn't. Also check at intake manifold, T
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Keoni
Novice
Nov 20, 2006, 3:42 PM
Post #3 of 7
(4763 views)
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Re: 94 S-10 high idle
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I would suspect a I.A.C motor ( idle air control motor ) is defective or needs cleaned. Remove the air cleaner take note of a small slit before the throttle plate. With the engine running spray carb intake cleaner ( cheap ok ) into the slit , enough to bog the motor but not kill it. Do this several times to exercise the iac then let it idle. I will agree it could be a vacuum leak but this is a good cheap service point .
Keoni
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Guest
Anonymous Poster
Nov 20, 2006, 6:03 PM
Post #4 of 7
(4760 views)
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Re: 94 S-10 high idle
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UNPLUG YOUR COMPUTER AND LOOK FOR MOISTER IN THE PLUGS MAKE SURE THERE IS NO WETNESS IN PLUGS MOISTER IS WHAT I HAD FOUND TO BE A HIGH IDLE ALONG WITH VACCUME HOSES INTAKE ANY TYPE OF VACCUME LEAKS
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Swooshski
User
Dec 18, 2006, 3:01 PM
Post #5 of 7
(4742 views)
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Re: 94 S-10 high idle
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I pulled the air filter & air induction hose off. I don't see a slit anywhere in the neck of the throttle body where the hose from the air cleaner attaches .... so I don't know what to say about that one.
I checked all vacuum hoses which seem to be in place and in good shape. I took a can of carb cleaner and gave each connection a few squirts to see if the idle would change ... it did not .... so that confirms that there are no leaks. I do not hear any type of hissing or anything that would indicate a possible leak (or at least one that I can find). I checked the PCV valve/connection and it's functioning ok.
If I unplug the 2-wire plug on the throttle body that is closest to the throat opening it does cause the idle to increase even higher, and drops back down a bit when I plug it back in. Although at a high idle, the engine runs smoothly. If I bump the accelerator quickly it takes a long time for the rpm's to drop down to idle speed again (if this helps). This motor had the EGR valve replaced on it about a year ago to meet inspection requirements if that helps too. But this problem just happened... overnight ... without the engine being touched.
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way2old
Veteran
/ Moderator
Dec 18, 2006, 5:23 PM
Post #6 of 7
(4737 views)
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Re: 94 S-10 high idle
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Look down inside the throttle body and see if you can see any gasket material inside the throttle. The full size trucks in that era were bad about sucking part of the throttle body gasket in thereby causing an internal vacuum leak.
Being way2old is why I need help from younger minds
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Guest
Anonymous Poster
Dec 19, 2006, 8:26 PM
Post #7 of 7
(4734 views)
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Re: 94 S-10 high idle
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check the plug for the water temp sensor i had put mechanical gauges in and took out the water temp sensor and it developed a high idel
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