Ford Fuel System :: Fast Idle Speed Holds The Throttle At 1500 RPM On Cold Start
May 5, 2017
Carburetor: Autolite 4100
Fast Idle Speed: 1250 RPM
Curb Idle Speed: 600 RPM (At normal operating temperature)
When I cold start my truck, the fast idle speed holds the throttle at 1500 RPM. I will let it idle about 30 seconds or so, and then I will tap the gas to bring the idle down.
When I do this, the idle will immediately drop all the way down, and too low for a cold engine. The engine won't stall, but it will hover just below 500 RPM, which is a bit too low to idle smoothly.
But when the engine is at operating temperature, the idle speed is 600 RPM and the engine will happily idle smoothly.
Shouldn't there be an "in between" speed? When I tap the gas pedal at 1500 RPM to bring the idle down some, shouldn't the speed drop down a little lower, like 1000 RPM since the engine is still a bit cold?
If so, what do I need to adjust? The Autolite 4100 works PERFECTLY otherwise.
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After my truck sits overnight it starts immediately and goes to fast idle for a few seconds, then ithe idle starts dropping until it gets to approx. 400 RPM.If I drive off immediately it will correct itself in a short while, otherwise I need to baby the engine speed until it runs on its own - usually five minutes.I cleaned the MAF and performed a MAF tap test with no success.
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My truck has developed a bad habit when it is cold (as in outside air below freezing and engine cold): The accelerator pump arm rubs against the throttle arm hard enough to bind the throttle partially open (NEVER a good situation!). I've removed the carb and verified that everything "looks" right:
1) The throttle shaft is in the right location and doesn't have any side to side movement.
2) The accelerator pump arm pivot is straight
3) The accelerator pump arm is straight (It's design makes it a bit difficult to just "bend" the arm side to side and I shouldn't have to do that anyway...)
4) The throttle arm is straight
After taking the arm off and straightening it out (repairing my attempts at a "field" repair...), verifying the linkage and then reinstalling and adjusting the AP, everything was working perfectly on the bench (kitchen table...), so I went ahead and reinstalled the carb (always fun at 10:30pm when it is 7F outside and the freaking wind is blowing at 30mph!).
By the time I got everything bolted down and hooked back up, the carb had cooled off a LOT, and the linkage was once more binding. I have no doubt that if I bring it in and let it warm back up, it will work perfectly.
So, what could be the problem? Do I just need to say the heck with it and hit the side of that lever with a file to get the cold clearance it just doesn't have? I can't imagine that this is a common problem with Holley 4160 carbs...
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I picked up a 90 f150 with the 302. it wont idle without a little throttle, so after a quick look under the hood i noticed alot of broken torn and missing vacuum lines. Where I can get some sort of diagram for routing?
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Fast idle 6.7 when cold remote start. My GM had what could be called a auto fast idle when it was cold it idle a lot faster.
It appears my 2012 f350 does not , Ford dealer said he could install a fast idle using one of the switches.
And then if I park truck with park brake on and switch on it when I start it will fast idle to around 1300.
My question is being if truck is started by remote , will not this switch be off and by being off fast idle will not work , is this not the case?
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Working on a 88 Ranger 2.9L 5-speed ext cab. The fuel pressure drops off fairly fast when turned off and I'm pretty sure that the check valve is bad. My question is, which pump has the check valve? It is a single mid tank set-up and has a pump in the tank and on the frame.
Pressure is fine while running. about 30psi @ idle and 40psi with no vacuum on the regulator. The pressure drops off within a couple of minutes which causes it to have to crank over for a bit to rebuild pressure and start.
It looks like the frame pump is readily available while the in take pump is special order. I just need to know which one has a check valve. I'm thinking the in tank pump, but I hate to waste money for the wrong pump.
Pressure drop rate
30 psi @ shut off
25 psi @ 1:05 min
20PSI @ 2:30 min
15psi @ 4:45 min
still dropping
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When I start my 1999 1.8 petrol passat it needs some throttle to start, low idle speed, misfires, drop in idle, so boot the throtle full - still no pick up and sits on 1000 rpm busy backfiring away! It started after fitting a new windscreen wiper motor, battery was disconnected but went back ok, all other electrics work and no warning on the dash. Didn't touch anything in the engine bay nor were there any issues before I changed the wiper motor.
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My 98 Chrysler sebring has a fast idle at about 1500, occasionally dies but will restart, and has been making the garage smell like gas. Can't seem to figure out the problem.
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The other day I disconnected battery, then removed and cleaned the throttle body. Now cold-start idle is high, and erratic,
goes to 1,600, drops to 1,000
- back to 1600, drops, up to 1,400
-- wavers there, and then finally,
starts to taper down to steady idle of about 650-700 rpm.
Since battery disconnected, does not seem there would be a chance for TB to "un-synch" with cars computer.
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I have an issue with extreme high initial idle at start up. I took my 1998 Ranger with a 3.0L to the local dealer to have some work done about a month ago. Long story short, my number six plug wire got burned against the exhaust rail.
Anyway, I guess they re-flashed the computer to the newest *.bin, or flash version. After that when I start the truck the tachometer jumps up to 2200 - 2300 RPM and then it settles down to about 1500 after a moment or two, then it finally adjusts itself to about 1100 for a few more seconds and eventually ends up at 900 - 1000 RPM.
I confronted Ford about this and they said that Ranger's and F-150's do have a tendency to do that at start up. Ordinarily I wouldn't be too concerned, however I believe that the 2200 - 2300 RPM high idle at start up at 0 F, a bit much.
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So I got a check engine light... did a scan and it said something about, "Cold Start Idle-Control System" and then it also has misfires on all of the cylinders and that it is running too lean.
I automatically went to check the intake, took it apart and the rubber coupler that connects the MAF sensor to the stage 2 pipe has a rip in it.
Now I'm freaking out thinking that maybe water... dust... dirt... has gotten into the engine.
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Bought my 2006, V6, about 2 months ago. This morning was the first really cold once since I bought the care. When I started it today, the idle speed was about 1200 RPM. It took a few minutes to warm up and then the idle speed dropped to normal. Quick question. Is this normal?
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Since having my engine replaced with a newer used engine block my idle speed when I first start it up or when it is cold is around 2000rpm which lasts for about 2-3 minutes until it begins to fall to the normal range of 1200-1400 and finally to 850 or 900rpm when warm. how can I fix this or is it okay to idle at 2000rpm for a couple of minutes? is it hurting anything?
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I just rebuilt the Autolite 4100 on the 390 in the 62 T-Bird I just purchased. Starts up and idles great, but when I apply slight throttle, the motor shuts off. If I apply a lot of throttle quickly, it picks up fine and drives with no problems. No sputtering, or backfiring. I just slightly apply the throttle, the RPMs drop, and the motor cuts out completely. Starts right back up when I turn the key, but does the same thing, at any temp.
I originally thought it was a vacuum leak, but checked what few vacuum lines there were, with no leaks to be found. Hooked up my vacuum gauge and it read at a steady 15psi.
New mechanical fuel pump, haven't checked the fuel pressure yet, but I installed a see through inline filter, and it's filled up and pumps fine.
Timing is at 8 degrees, and vacuum advance is hooked up to the only vacuum line in the carb. New cap, rotor, plugs and wires.
I adjusted the idle mixture screws down until the idle dropped, then turned them out a half turn (I've read on here it should only be a 1/4 turn, so I'll adjust that later today). When I was messing with the carb yesterday, I noticed the inlet check ball retaining screw was leaking a bit of fuel, so I went over the carb and checked all the screws and tightened down what needed it.
When I rebuilt the carb, I left the original needle & seat assembly, since they were in great shape, and the ones in the rebuild kit were much smaller. The choke plate needs to be adjusted, as it doesn't open up all the way at full temp, but the engine did the same thing with the plate held open all the way open.
I've gone through everything else I think it could be, so I'm figuring it's the carb. This is my second carb rebuild ever (first was a Motorcraft 2150) and it went smoothly, and I double checked the floats and measurements.
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Is it possible to take an 'throttle emissions control solenoid" off a 2150 Carburetor and swap it with a different solenoid, say something like an idle swap?? I can't find a new throttle emissions control solenoid, but I see plenty of idle stops.
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I noticed last night while messing with my truck that I have a constant small spark on my throttle linkage on my carb. BTW, it's a 77F250 with a quick fuel Ethanol carb with an electronic choke. That really probably don't make a difference anyway. Is this a common thing and do I need to run a grounding wire from the carb to the rest of the engine?
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My 1981 302 dosent like this 4160 apparently. When i start my truck it shudders on first seconds of startup and whenever i touch the throttle. It runs and operates, but im getting concerned.
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'99 Explorer 5.0 doesn't want to start in the cold weather, below 30. After it finally starts it runs great and will start all day. It cranks fast but it doesn't get driven every day.
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1991 Buick Regal, 3800 V6
Having a rough idle on a cold start. After some research and closer inspection of the vehicle, I'm quite certain I have at least one leaking injector that is flooding a cylinder and causing the car to misfire on a cold start. I'm also not at the gas mileage I should be at.
So I'm wondering, is fuel injector replacement as straightforward of a job as it looks? Any major issues I could run into in doing a replacement?
I'm planning on replacing all six injectors (I can get them for $50 each buying online with a discount code), but given that the vehicle is so old am I better off just replacing the faulty ones? I'm assuming pulling the spark plugs and seeing which cylinder is wet will tell me which I need to replace.
And one more question: Is there a way to depressurize the fuel system when I park the car for the night, thus preventing fuel (or most of it) from leaking into the engine until I get this fixed? I've read that just unscrewing the gas cap can depressurize the system.
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I was using the method of spraying starter fluid around the intake and found a pretty significant vacuum leak around the throttle shaft on the drivers side. The carb is a 2 barrel holley. What are some different ways to seal a throttle shaft vacuum leak? Could I take it apart and seal it with a plastic O-ring for now?
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I have a 1998 Chevrolet Prizm that will not fast idle when it is started in cold weather the first thing in morning. what could be the problem?
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