Fast idle not working properly?
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Car: '83 Camaro Berlinetta
Engine: 2.8L v6 (LC1)
Transmission: A3
Fast idle not working properly?
'83 Camaro Berlinetta 2.8l V6 stock carb. Recently installed new choke thermostat as the PO had removed it and installed a manual choke, which wasn't even hooked up properly.
General question about the fast idle function really... What is it meant to do? Is it meant to heat up the engine when it's cold?
And if so, why does my car not initiate fast idle until it's already warmed up? And even further, it never uses the maximum fast idle... (There are 3-4 fast idle settings on the carb to my understanding, the lowest being ~1000 rpm, the highest at ~2200 rpm) Why not?
General question about the fast idle function really... What is it meant to do? Is it meant to heat up the engine when it's cold?
And if so, why does my car not initiate fast idle until it's already warmed up? And even further, it never uses the maximum fast idle... (There are 3-4 fast idle settings on the carb to my understanding, the lowest being ~1000 rpm, the highest at ~2200 rpm) Why not?
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Fast idle keeps the engine running when the intake tract is too cold to properly evaporate the liquid gasoline in the airstream.
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Car: '83 Camaro Berlinetta
Engine: 2.8L v6 (LC1)
Transmission: A3
Re: Fast idle not working properly?
So, because the gas is to cold to vaporize, the solution is to put more gas in? That doesn't seem right.
Furthermore, why would it turn on after the engine has warmed up?
Furthermore, why would it turn on after the engine has warmed up?
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Car: 85 Trans Am
Engine: 98 Vortec 350 LT1 Cam w/ TPI
Transmission: T56
Axle/Gears: 9 bolt 3:27
Re: Fast idle not working properly?
If your car only fast idles when it warms up then it is not set properly. Most likely the choke thermostat is not set properly. Depending on the tension of thermostat it will set the stage of fast idle. The stronger the tension the harder it pulls the choke closed and engaging the higher stage of fast idle. As it warms up it releases its tension and thus stepping down the fast idle while opening the choke flap.
There should also be a fast idle screw as well but this only adjusts the overall speed of all the stages of fast idle. So if you lower the highest stage of fast idle by say 500 RPM then all the lower stages will be 500 RPM lower.
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Re: Fast idle not working properly?
Remember on carbureted cars you MUST stab the gas once before you turn the key the first time on an overnight-cold start. That "unloads" the linkage and allows the choke to close as well as the fast idle cam to engage. One of the little differences between a carb'ed motor and an EFI one.
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Car: '83 Camaro Berlinetta
Engine: 2.8L v6 (LC1)
Transmission: A3
Re: Fast idle not working properly?
I can have visibly see the choke closed as far as it goes, start the car after hitting the gas once, see the choke closed fully still, and it will only idle at around 600rpm (at 20 degrees far in this instance)...
I'll have a look at it this weekend when I have more time, if I get time even. Finals are coming up and I have a lot of projects due.
I'll have a look at it this weekend when I have more time, if I get time even. Finals are coming up and I have a lot of projects due.
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Car: 85 Trans Am
Engine: 98 Vortec 350 LT1 Cam w/ TPI
Transmission: T56
Axle/Gears: 9 bolt 3:27
Re: Fast idle not working properly?
Just because the flap is all the way closed does not mean the fast idle is fully engaged. After the flap is closed you can still turn the thermostat to increase its tension and further engage the higher fast idle.
#9
Re: Fast idle not working properly?
I can have visibly see the choke closed as far as it goes, start the car after hitting the gas once, see the choke closed fully still, and it will only idle at around 600rpm (at 20 degrees far in this instance)...
I'll have a look at it this weekend when I have more time, if I get time even. Finals are coming up and I have a lot of projects due.
I'll have a look at it this weekend when I have more time, if I get time even. Finals are coming up and I have a lot of projects due.
#10
Re: Fast idle not working properly?
There's still something wrong with your choke linkage if fast idle cam step isn't engaged after punching the throttle and lifting your foot off the pedal before cranking, on a cold start the choke spring should rotate the fast idle cam to the highest step (on a 60*F or less day) and the engine should idle around 2000RPM until you hit the pedal, at which time the choke vacuum pulloff has opened the choke partially and slapping the pedal after startup will allow the fast idle cam to come off the highest step. Too much oil and/or grease on the pivot shaft of fast idle cam will cause it to stick and not move freely, I use ATF (or WD-40) on mine as motor oil or lithium grease makes them stick too much.
#11
Re: Fast idle not working properly?
There's still something wrong with your choke linkage if fast idle cam step isn't engaged after punching the throttle and lifting your foot off the pedal before cranking, on a cold start the choke spring should rotate the fast idle cam to the highest step (on a 60*F or less day) and the engine should idle around 2000RPM until you hit the pedal, at which time the choke vacuum pulloff has opened the choke partially and slapping the pedal after startup will allow the fast idle cam to come off the highest step. Too much oil and/or grease on the pivot shaft of fast idle cam will cause it to stick and not move freely, I use ATF (or WD-40) on mine as motor oil or lithium grease makes them stick too much.
The fast idle cam is likely engaged from what I read. As the car warms up a bit (choke blade starts to open) the idle speed picks up. This is a classic symptom of a choke pull off that is not functioning properly. It may be something else, but from what I read, this is the first thing on my list.
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Re: Fast idle not working properly?
I can have visibly see the choke closed as far as it goes, start the car after hitting the gas once, see the choke closed fully still, and it will only idle at around 600rpm (at 20 degrees far in this instance)...
Those vacuum canisters that perform this function do go bad sometimes.
#13
Re: Fast idle not working properly?
Hold on a minute. After you fire the engine the choke is still FULLY closed? It shouldn't be. There should be a vacuum canister somewhere on the outside of the carb that should pop the choke plate slightly open as soon as there is manifold vacuum present (i.e. the engine is fired and running). It's there specifically to prevent flooding the motor immediately after startup and keep it from burbling and gaging from an insanely-rich mixture that would happen if the motor was to be running with the choke FULLY closed.
Those vacuum canisters that perform this function do go bad sometimes.
Those vacuum canisters that perform this function do go bad sometimes.
What you are describing is called the choke pull-off. See my previous posts about this.
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Re: Fast idle not working properly?
Yes, I know. Sorry, I somehow missed that you already covered the same ground I did. Usually I read more carefully than that, but apparently not in this case.
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Re: Fast idle not working properly?
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Car: '83 Camaro Berlinetta
Engine: 2.8L v6 (LC1)
Transmission: A3
Re: Fast idle not working properly?
I've found out what the problems are. Yes, problems.
1: Gunked up linkage. Cleaned it up and everything moves smoothly.
2: Bent linkage. Found that out after a thorough cleaning. (No, I didn't bend it while cleaning, as I only used spray cleaner and compressed air). This was the culprit for lack of high idle.
3: Old broken choke pulloff. Got a new one installed.
Now everything works much better.
Thank you for all the suggestions, info, and advice.
1: Gunked up linkage. Cleaned it up and everything moves smoothly.
2: Bent linkage. Found that out after a thorough cleaning. (No, I didn't bend it while cleaning, as I only used spray cleaner and compressed air). This was the culprit for lack of high idle.
3: Old broken choke pulloff. Got a new one installed.
Now everything works much better.
Thank you for all the suggestions, info, and advice.
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Fast355
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12-02-2016 06:33 PM
28, 83, ajust, berlinetta, camaro, carb, carberated, choke, do, fast, idle, intermotive, pulling, thermostat, v6, working