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Won't idle
I was out in the foothills this morning (where it is much cooler) and noticed that I had to blip the accelerator to get my idle down from 1500 to 900 rpm (Holley 3310, electric choke, vacum secondaries). I also noticed that my mpg was way off for the day. What I discovered is that my choke was not opening completely, however, once I got back down to the flat lands where it was a little warm and more stop-n-go the problem went away. I started thinking about this and remembered that I installed a 160 degree thermostat. I'm thinking the engine isn't staying at a temp when it is cool/cold to operate the electric choke properly and I need to bump up the thermostat to 180. The puzzling thing is, I've never had this problem before today.
Any thoughts on this? |
Hi Phil,
You indicate an electric choke, which if the usual variety is simply a 12V source to a heating element within the choke housing that heats the spring which unloads the choke butterfly... it may take a little longer to open fully in colder temps but the overall choke action is irreversible as long as the choke sees a 12V source i.e. as long as the key is in "run" position. So yours should not be able to remain partially closed after driving awhile... my 2c worth is that your choke is malfunctioning, losing its voltage source, linkage sticking, heater element failing, one of those type things :3DSMILE: With your fast idle staying up I assume the choke fast idle cam is still active confirming your choke is not releasing fully. The choke release is independent of your thermstat setting. Check your choke butterfly and linkage - wiggle it open/close with the throttle unloaded to check for binding etc - put 12V to the choke to test its function. Make sure your 12V source remains contant to the choke, no wire probs etc. The electric choke is simply an "on or off" system, so when "on" has to open fully within a set interval of time if it is functioning properly. Good luck! |
Don,
That's great information - THANKS! I agree completely with your diagnosis - it makes sense. But why, at higher temps, does it work properly? Maybe a marginal failure with the heater element (?) I'll do some further "tinkering".... and again, thanks for the assistance. |
Don,
You were right on - a broken wire at the spade clip. Must have been working some times and not others. I was thinking it was an engine temp issue when it intermittently made contact. Guess I was to close to the problem and over diagnosing. I'm changing the T/stat to 180 tomorrow. Thanks again. |
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Hey Phil, glad you got it fixed! :D :D |
Don that was a great call re the choke. Phil...when I bought my car it would run so cool especially on cooler days I didn't think there was a thermostat installed. I checked with the auto parts store and Ford specs a 195 for the fe390. So thatt's what I installed but in doing so I found a 160 stat there already. My car runs MUCH better at temp always around 190 hot or cold weather, warms up to temp much faster, gets the oil warmer sooner...all good things. I think 180 is still too low for you. But that's only because it's too low for me. I have read other post stating 210 running temps is what you need for maximum HP. You may want to reconsider the 180. There are a lot of guys here with much more experience than me with engines. Just so you know my suggestion is from somewhat limited experience. John
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Phil,
- 180 with a small steam hole drilled in it, distilled water, Water Wetter. ;) You'll find your FE will generally run crisper and perform better if you help it to sustain optimum operating temp; especially on those cooler days and nights. Watch what happens to your throttle response and takeoffs as well. |
Low temps are a real issue ESPECIALLY if you run aluminum heads. They will suck the heat out of the combustion charge, and the engine will be WAY down on power. That's why most newer cars OEM run between 210-220 in normal conditions (with heavy dose of coolant) to control boiling & loss of coolant. By doing so increased temps help with emissions too.
Don: good call, those electric chokes take a fair amount of current to make them function. Question: Why is a choke necessay? Most of us run the motors a little "Fat" anyway. With the low profile air filters use by many in these cars, you would be well served to remove the choke housing entirely and blend the entry edges or change to an "HP" type main body on a Holley. FACT! |
To all FE owners. Please DO NOT run anything less than a 185-degree thermostat, expecially if you have a functioning oil cooler. Want proof? Run your engine with a 165-degree thermostat for a while, then pull the valve cover breather out. Probably looks like a chocolate milkshake around the bottom of the breather. I had nighmares after looking at that.
The thermostat does not have anything to do with engine cooling, only engine warmup. Sorry for the lecture, but seeing that gunk was a life-altering experience. Brian |
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