93 Pickup 2.3L High Idle

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93 Pickup 2.3L High Idle

Postby tjmac0967 » Sun Sep 26, 2010 3:41 pm

My 1993 Isuzu Idles extremely high. I brought it to a shop and he said I need a new carb, but I think it is something else. There is this Idle switch that is to the left of the carb. It has an electrical whip on one end, and it plugs into a vacuum line. According to vacuum line diagram underneath the hood, this is called an idle switch. I have checked every part store around and online, and I cannot find anything. When I have this Idle switch plugged in, the idle is so high it hits the rev limiter. If I unplug it the idle will go down, but it is still very high and erratic. So, I think that it is this switch. Does anyone know what this is called, or where I can get one? Or possibly someone sell me one? I would really appreciate this because this truck is a beauty, it is just not mechanically sound right now. I really appreciate your responses!
1993 Isuzu Pickup 2.3L.

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Re: 93 Pickup 2.3L High Idle

Postby Finetuned-2 » Sun Sep 26, 2010 10:50 pm

I had a similar problem with my 92, and changed to a Weber Carb. I can now set the idle without a problem! The idle switch is for the A/C, to boost the idle when the A/C is turned on. I think the guy in the shop told you right.

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Re: 93 Pickup 2.3L High Idle

Postby terrirae » Mon Sep 27, 2010 3:20 am

Also have had the problem with a different solution and positive results. I did the following and it resolved the high idle issue.

1)Checked throttle linkage and cleaned it to make sure it wasn't sticking.
2) Adjusted the idle as best as I could (had trouble getting my external tachometer to work due to solid state coil)
3) The thing that really solved my high idle issue and I often neglected was adjusting the Valve clearances (suppose to be adjusted every 15000 miles). Irregular, ticking sound is usually heard in the engine - sorry not sure how else to describe it.
4) also check your vacuum hoses and replace them if they have not been. There is another idle control on the inside of the air cleaner which if the vacuum hose that goes from the carb. to the air cleaner connection is worn or cracked can also cause idle problems. Often this causes surging vs. a high idle but it is worth checking.

I always like to start simple before replacing parts. If you just got the truck and don't know the maintenance history, I would start with replacing the vacuum hoses and then the Valve adjustment plus other normal tune up and maintenance steps. It has helped me remove high idle as well as inconsistent idle in the past.

Hope this helps.
1992 2.3 4 cyl engine 4x2
Denver, CO

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Re: 93 Pickup 2.3L High Idle

Postby SC_PUP » Mon Oct 11, 2010 2:14 pm

I agree, start simple first. I've only had my Pickup for a few days. I had a similar problem, a high idle and the truck wanted to stall. The prior owner just 'lived with it' for years. He had the carb changed and still had the same problem. I just took the time to look at all the vac lines. I found missing, disconnected and dry-rotted lines. The main problem was that the line from the EVAP canister to the EGR valve was not hooked up. Just reconnecting/replacing lines solved the stalling problem, and the idle seemed to naturally lower itself as well. From there, I also used one of the idle set screws to back the idle down even more-- it was artificially bumped up to compensate for stalling.

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Re: 93 Pickup 2.3L High Idle

Postby WillyBoy » Thu Sep 20, 2012 12:48 am

hello there. Two years had already passed since the topic here was posted and I do apologize for that. The topic here caught my attention because this was my issue a couple of months ago. Its my first time to have a mini pickup truck like isuzu. Fortunately I saw this thread, I might follow the steps that was posted here. I hope that this will help me. thanks.
Even if the morrow is barren of promises, nothing shall forestall my return. - Loveless, Act III
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