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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / November 2006Idle problems when temp is cold...
Vehicle is a 1986 Chevy G10 van. Canadian 4.3 V6 with a four barrel (M4MED?) carb. Automatic trans. 52,000kms on her. I thought I had this problem licked, but it came back yesterday... (temp dropped to around 0'C) Normally, the van runs really nicely, except for a touch of a lope. (This van sat for a few years, so I'm suspecting that the lope is caused by unequal compression due to corrosion, etc.) The problem is, that when it's cold outside (it was around 0'C last night), I can get the van started fine, but within a few minutes the idle starts dropping... lower... lower... lower... stall. Usually when this happens and I'm driving around I end up using one foot on the throttle, keeping the revs up, and the other foot for the brake pedal. After five to ten minutes of this the van runs fine. When the idle is dropping, the exhaust smells strongly of fuel. I've tried adjusting the low idle screw while the idle was dropping and there was no contact between the screw and the stop, indicating that the fast idle was still holding the throttle valve open to keep the idle up. I haven't had the opportunity to pull the doghouse off and pop open the air cleaner when the van is running poorly. From what I could see last night with my flashlight, while at the side of the road, there appeared to be gasoline leaking from the throttle valve shaft at the bottom of the carb. The choke on this carb is electric, and still riveted into its stock adjustment. This carb has been on and off this engine a few times, and disassembled at least once - so any adjustment could be messed up. Now, for what I do know... - Cap, rotor, wires, plugs (platinum) are new & timing is good. - Air filter, PCV valve and PCV filter are new. - Fuel filter is new. - Gas is fresh. - Thermostat is 180' and new. - Oil & filter are new. - EGR is new and correctly valved for this motor. - Vacuum lines are OK and timing advances normally. I've got two questions... 1. What's wrong? Any help is appreciated. 2. What kind of power is fed to the electric choke? Could I short it to 12v to test? > Vehicle is a 1986 Chevy G10 van. Canadian 4.3 V6 with a four barrel > (M4MED?) carb. Automatic trans. 52,000kms on her. [quoted text clipped - 48 lines] > 2. What kind of power is fed to the electric choke? Could I short it to > 12v to test? I believe that you should have a 195 thermostat instead of a 180. Too cold a thermostat could be part of your problem. You need to check the operation of the choke and the choke pull-off. With the vehicle cold. remove the air cleaner so you can watch the choke. Set the choke by opening and closing the throttle. The choke plate should close completely. Start the van and watch the choke plate, it should open slightly ( about 1/4 to 1/2 inch) as soon as the engine is running. If it doesn't open slightly when the engine is started suspect a bad or misadjusted choke pull-off. Then, as the engine warms up, the choke should continue to open further until it is fully open. If it dosen't open further I would suspect an inoperative choke. I believe the choke is fed by 12 volts. Instead of jumping 12 volts to the choke check to see if you have power to the choke wire when first started. I see two problems. First off, with a 180 thermostat in it, you will 'always' need to two foot drive until it warms up. What happens is the choke is on an electric timer that doesn't give a crap about how warm the engine 'really' is when it shuts the choke off and you have a thermostat in there designed to not let the engine warm up fast. These are not a good combination in the winter. This will also give you crappy heat inside. You should have a 195 in there for winter. And second you are describing a sticky float needle valve. When it sat the gas evaporated and left gummy stuff behind. This can make the choke needle stick open, when it's cold especially and any old time eventually. I don't know what is in today's gas mixes, but that happens to my float needle every couple years. It is a pain. I can either get a carb kit that comes with a new needle and seat or I have removed it from the outside and just cleaned the sucker up. The gummy junk is visible as a stain. On my carb, I can remove the gas line and then take out the float needle and seat. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > Vehicle is a 1986 Chevy G10 van. Canadian 4.3 V6 with a four barrel (M4MED?) > carb. Automatic trans. 52,000kms on her. [quoted text clipped - 48 lines] > 2. What kind of power is fed to the electric choke? Could I short it to 12v > to test? > I see two problems. First off, with a 180 thermostat in it, you will > 'always' need to two foot drive until it warms up. (not true) >What happens is the choke is on an electric timer (no timer, current from altenator) that doesn't give a crap about how warm > the engine 'really' is when it shuts the choke off and you have a > thermostat in there designed to not let the engine warm up fast (incorrect, thermostats do not change rate of warm up). >These are not a good combination in the winter. > > This will also give you crappy heat inside.You should have a 195 in > there for winter. (heat will be fine) > And second you are describing a sticky float needle valve. When it sat > the gas evaporated and left gummy stuff behind. This can make the choke needle stick open (no such thing) , when it's cold especially and any old time > eventually. > [quoted text clipped - 64 lines] > > 2. What kind of power is fed to the electric choke? Could I short it to 12v > > to test? does a carburator regulate air, or gas ? > > I see two problems. First off, with a 180 thermostat in it, you will > > 'always' need to two foot drive until it warms up. [quoted text clipped - 88 lines] > > > 2. What kind of power is fed to the electric choke? Could I short it to 12v > > > to test? Before your time eh? You should have a 'little' knowledge before saying what is 'true' or not. Maybe go ask your daddy. Mike > does a carburator regulate air, or gas ? > [quoted text clipped - 90 lines] > > > > 2. What kind of power is fed to the electric choke? Could I short it to 12v > > > > to test? > > I see two problems. First off, with a 180 thermostat in it, you will > > 'always' need to two foot drive until it warms up. > (not true) Got news for ya! That combo he is using will 'always' need 2 foot driving until it warms up and even with the 'right' t-stat, the electric 'timer' choke causes 2 foot driving when it's really cold out until the engine really warms up. I went with and recommend to others up here in the Great White North where it gets cold a manual choke to overcome this design defect. > >What happens is the choke is on an electric timer > (no timer, current from altenator) The bimetal spring inside the electric choke opens according to how 'long' the electricity has been going to it. This is a 'timer', nothing else. > that doesn't give a crap about how warm > > the engine 'really' is when it shuts the choke off and you have a > > thermostat in there designed to not let the engine warm up fast > (incorrect, thermostats do not change rate of warm up). BS. When it's 'really' cold out the t-stat opens at 180 and the engine will stay there, this is not really 'warmed up' enough for good carb operation and manifold heat to atomize the gas. Lots of pollution controls won't turn on properly at this low of a temperature, they want the 195 t-stat. > >These are not a good combination in the winter. > > > > This will also give you crappy heat inside.You should have a 195 in > > there for winter. > (heat will be fine) You obviously have never lived anywhere cold before. A 180 gives crap for inside heat in the 'real' cold. > > And second you are describing a sticky float needle valve. When it sat > > the gas evaporated and left gummy stuff behind. > This can make the choke needle stick open > (no such thing) That was a typo as 'most' might figure out by my next statement.... It makes the 'float' needle stick. Mike > , when it's cold especially and any old time > > eventually. [quoted text clipped - 65 lines] > > > 2. What kind of power is fed to the electric choke? Could I short it to 12v > > > to test? >> > I see two problems. First off, with a 180 thermostat in it, you will >> > 'always' need to two foot drive until it warms up. [quoted text clipped - 4 lines] > 'timer' choke causes 2 foot driving when it's really cold out until the > engine really warms up. 95% of the time, the van works fine. >> that doesn't give a crap about how warm >> > the engine 'really' is when it shuts the choke off and you have a >> > thermostat in there designed to not let the engine warm up fast >> (incorrect, thermostats do not change rate of warm up). > > BS. > When it's 'really' cold out the t-stat opens at 180 and the engine will > stay there, this is not really 'warmed up' enough for good carb > operation and manifold heat to atomize the gas. Lots of pollution > controls won't turn on properly at this low of a temperature, they want > the 195 t-stat. Thermostats don't change the rate of warmup. The engine warms up at the same rate regardless. Once you get close to the opening temp, THEN you'll start seeing the differences. >> >These are not a good combination in the winter. >> > [quoted text clipped - 4 lines] > You obviously have never lived anywhere cold before. A 180 gives crap > for inside heat in the 'real' cold. This I will agree with. The heat just ain't the same as it was with the old thermostat. I have no idea what it was though. I figured with such a low mileage engine that I'd be better off with a cooler thermostat. There was even a 160 degree available, but decided that was too low. I think I'll go to the trouble of pulling the 180 and putting a 195 in, just for the sake of getting more heat. Any idea what the difference between a "normal" thermostat and a "performance" thermostat are: http://ec3.images-amazon.com/images/P/B000C6HSL6.01._AA280_SCLZZZZZZZ_V50825922_.jpg http://ec1.images-amazon.com/images/P/B000C6AX54.01._AA280_SCLZZZZZZZ_V50453740_.jpg >> > And second you are describing a sticky float needle valve. When it sat >> > the gas evaporated and left gummy stuff behind. [quoted text clipped - 3 lines] > That was a typo as 'most' might figure out by my next statement.... It > makes the 'float' needle stick. Definately seems like this, or something similar. Unfortunately I haven't been able to pull open the air cleaner when I'm having problems. It never happens when I've got the toolbox in tha van. Now I've got the doghouse unbolted from the floor. I'll be ready the next time I have issues. > >> > I see two problems. First off, with a 180 thermostat in it, you will > >> > 'always' need to two foot drive until it warms up. [quoted text clipped - 6 lines] > > 95% of the time, the van works fine. It is the -20 and -30 days where that timer choke really shows it's limitations. I love the manual choke. Easy to install too. Canadian Tire sell the kits for it. You would want the heavy duty truck one. > >> that doesn't give a crap about how warm > >> > the engine 'really' is when it shuts the choke off and you have a [quoted text clipped - 12 lines] > rate regardless. Once you get close to the opening temp, THEN you'll start > seeing the differences. Yup, just having it stay at 180 on real cold days makes for issues. If it can warm up higher before the t-stat opens and therefore 'faster to a good operating temperature' then the issues diminish. > >> >These are not a good combination in the winter. > >> > [quoted text clipped - 18 lines] > http://ec3.images-amazon.com/images/P/B000C6HSL6.01._AA280_SCLZZZZZZZ_V50825922_.jpg > http://ec1.images-amazon.com/images/P/B000C6AX54.01._AA280_SCLZZZZZZZ_V50453740_.jpg The last 'performance' t-stat I bought had a 'fail-safe' in it that failed it open if it overheated. I don't know 'what' temperature that SOB was calling 'overheated', but I failed it open in the first 3 months of having it in there and then ended up with an open t-stat and no heat inside come the first cold snap. I run hard in 4x4 low on hot days though which does get the engine pretty warmed up. It never boils over though. I tossed it and put a normal one back in. > >> > And second you are describing a sticky float needle valve. When it sat > >> > the gas evaporated and left gummy stuff behind. [quoted text clipped - 10 lines] > Now I've got the doghouse unbolted from the floor. I'll be ready the next > time I have issues. If you are lucky, the needle and seat are under the gas line, but I don't know on your carb. You might want to get even a cheapie Haynes Repair manual for your vehicle. It will have basics like that in it. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) Good Luck on your choke timer. Let me know when you find it. LMAO. > > >> > I see two problems. First off, with a 180 thermostat in it, you will > > >> > 'always' need to two foot drive until it warms up. [quoted text clipped - 93 lines] > Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 > (More Off Road album links at bottom of the view page) You obviously have never seen a carburetor or a bimetal electrically activated spring. When electricity goes to this bimetal spring, it opens up according to how 'long' or 'for how much time' the electricity has been going to it. Too simple for you idiot techs eh? If the computer don't tell you what's up, you are screwed. Mike > Good Luck on your choke timer. Let me know when you find it. LMAO. > [quoted text clipped - 95 lines] > > Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 > > (More Off Road album links at bottom of the view page) > When electricity goes to this bimetal spring, it opens up according to > how 'long' or 'for how much time' the electricity has been going to it LOL Electricity goes to the choke constantly, as long as the engine is running. the is no on/off time frame. The stat reacts to temperature. Apply current, it opens. Take current away, it closes. How bout the ones that use heat from the manifold to operate. I guess there's something that shuts the heat off !?! LOL > You obviously have never seen a carburetor or a bimetal electrically > activated spring. [quoted text clipped - 106 lines] > > > Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 > > > (More Off Road album links at bottom of the view page) >> When electricity goes to this bimetal spring, it opens up according to >> how 'long' or 'for how much time' the electricity has been going to it > LOL > Electricity goes to the choke constantly, as long as the engine is > running. the is no on/off time frame. The stat reacts to temperature. > Apply current, it opens. Take current away, it closes. How bout the > ones that use heat from the manifold to operate. I guess there's > something that shuts the heat off !?! LOL As soon as the power gets to the choke it begins to open. It takes time for the heat to rise. An instantly opening choke would be pretty useless. Some heat in the choke will be lost to the atmosphere with more on cold days than warm ones, but that difference is going to be rather small with an electric element. The consquence is that warm day or cold day the choke opens at a similiar rate and is fully open in about the same amount of time as on a cold one. The engine however is a rather large mass of metal and coolant and oil. There is a considerable amount of mass to warm up, not to mention surface area causing that heat to be lost. (Then the fact that materials are also good conductors of heat, quickly drawing heat from the inside to the outside surface) Thusly, on a cold day, when the electric choke reaches full opening, the engine won't be as warm as it would be on a warm day when the choke is fully open. The electric choke will be a compromise that will work at most temperatures, however when one gets to extreme temperatures like those being discussed, the rate difference between the choke and the engine warming up will be most pronounced. Of course this could be adapted by using some sort of temperature compensating control system on the electric choke. Which eventually gets us into modern vehicles with temperature sensors and computer engine management. Of course the opening of a manual choke operated correctly will be adapted by the operator to the prevailing conditions. >>When electricity goes to this bimetal spring, it opens up according to >>how 'long' or 'for how much time' the electricity has been going to it > > LOL > Electricity goes to the choke constantly, as long as the engine is > running. SOME of them work that way. Not all of them. Most have electric thermostats inside the choke that turn off the electricity once the choke gets hot enough, or don't turn it on at all if the ambient temperature is high enough (ie, the engine has been run recently). > >>When electricity goes to this bimetal spring, it opens up according to > >>how 'long' or 'for how much time' the electricity has been going to it [quoted text clipped - 9 lines] > if the ambient temperature is high enough (ie, the engine has been run > recently). What are you going on about? Automatic Chokes on carbs default to off or closed. They need constant input to 'stay' open. The input we are talking about in 'this' thread is electricity. As long as the electric choke's bi-metal element sees power, it stays open once it has heated up and expanded to the open position. If the power shuts off with the engine running, the choke closes and the engine chokes out. These fancy gizmos are before computers, purely electromechanical devices that obviously seem to screw up computer thinking brains. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) First you post this: I see two problems. First off, with a 180 thermostat in it, you will 'always' need to two foot drive until it warms up. What happens is the choke is on an electric timer that doesn't give a crap about how warm the engine 'really' is when it shuts the choke off and you have a thermostat in there designed to not let the engine warm up fast. These are not a good combination in the winter. And all through the thread, you talk about a choke timer/choke timer relay. Then your last post has these remarks: As long as the electric choke's bi-metal element sees power, it stays open once it has heated up and expanded to the open position. If the power shuts off with the engine running, the choke closes and the engine chokes out. No which is it?! Electric chokes have timers?! Electric chokes don't have timers?! Does the choke see power all the time, or sometime?! ( I know the answer, so don't bother.) And who knows what you mean when you say: "First off, with a 180 thermostat in it, you will 'always' need to two foot drive until it warms up. ( What?! Don't try to explain this either.) And your little derogatory remarks are so cute. You know, all of these that you put in your posts; 1)"You should have a 'little' knowledge before saying what is 'true' or not. Maybe go ask your daddy" 2)"You are a total moron aren't you?" 3)"Besides having no clue about a carburetor, you also apparently cannot read either" 4)"Too simple for you idiot techs eh? If the computer don't tell you what's up, you are screwed." 5)"You are an obvious idiot with no mechanical knowledge. I 'really' hope you were kidding about working on customers vehicles." 6)"Is that so very hard to understand? I know, before your time and with no diagnostic computer to explain it just too confusing and too simple of a concept to handle eh" 7)"These fancy gizmos are before computers, purely electromechanical devices that obviously seem to screw up computer thinking brains." And that's just in this thread. Sheesh. You are da man! Now into the hermetically sealed "Spam Can" with you, and bury you deep in the waste pile at Weirdo Ville. "PLONK" OK kids... play nice! : ) With a 180' thermostat, there will be NO difference in cold startup. There MAY be a difference in the heater temp once the thermostat is fully open. Just because the thermostat opens at 180' doesn't mean that the engine won't get any hotter. The problems I'm having with my van are either A) a faulty electrical choke or electrical fault at the choke OR B) dirty float valve that sometimes lets the fuel flood the carburetor. An electric choke gets warmer when power is applied. When warmer, it moves the choke plate in the carb. Once it's fully warm the power stays on and the choke plate stays open. The choke does not go to full open instantly, but opens more as it warms up. If it's colder outside, it may cause the choke to open slower. A mechancially heated choke will do a better job when extremely cold, but both should be fine. > First you post this: > I see two problems. First off, with a 180 thermostat in it, you will [quoted text clipped - 47 lines] > > "PLONK" The trouble with the 180 thermostat and the choke is the engine starts it's cooling cycle at 180 taking appreciable time to get up hotter even if it can on a real cold day. The choke's bi-metal spring is 'timed' to be fully open about the same 'time' a 195 would have the engine heated up so the gas vaporizes nice on an average temperature day. With the cold t-stat the engine will want more gas until it actually finishes warming up so you need to 2 foot drive them or wait. They are fine or not as bad in warmer temperatures, but that first stop after you head out can be a stall still. This is aggravated in high humidity also it seems. I got tired of waiting because I need to 3 foot drive with my 5 speed, so went with a manual choke. It works in 'all' temperatures and humidities. :-) I think your choke should be ok once you change the t-stat. If it had a bad connection, it would be staying closed bogging out the engine. The float needle is a regularly needed clean for me as I mentioned.... As for internal heat, I have had crap for heat in any vehicle with a cold t-stat. Back in my days in garages and big V8's, some folks would put a 180 in for the summer and switch it out for the 195 come winter. Mike > OK kids... play nice! > [quoted text clipped - 16 lines] > open slower. A mechancially heated choke will do a better job when extremely > cold, but both should be fine. > Now into the hermetically sealed "Spam Can" with you, and bury you deep > in the waste pile at Weirdo Ville. > > "PLONK" Please leave me 'plonked'! I sure don't need someone who says they don't know if a carb controls fuel or air trying to correct me on carb related problems. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) Willy wrote: > > When electricity goes to this bimetal spring, it opens up according to > > how 'long' or 'for how much time' the electricity has been going to it [quoted text clipped - 4 lines] > ones that use heat from the manifold to operate. I guess there's > something that shuts the heat off !?! LOL You are an obvious idiot with no mechanical knowledge. I 'really' hope you were kidding about working on customers vehicles. Once the choke's bi-metal spring has opened, it 'stays' open as long as it has power via a 'running' engine. Same for the ones with the heat pipes. Once they are warmed up, they 'stay' warmed up as long as the engine is running to provide heat. Is that so very hard to understand? I know, before your time and with no diagnostic computer to explain it just too confusing and too simple of a concept to handle eh. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) LOL I guess the spring says, oh thats enough electricity. I don't need any more right now. What's it do, send it back to the altenator?! LOL You got some damn smart springs! > You obviously have never seen a carburetor or a bimetal electrically > activated spring. [quoted text clipped - 106 lines] > > > Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 > > > (More Off Road album links at bottom of the view page) > > > > > >> > I see two problems. First off, with a 180 thermostat in it, you will > > >> > 'always' need to two foot drive until it warms up. Got news for ya! That combo he is using will 'always' need 2 foot > > > driving until it warms up and even with the 'right' t-stat, the electric > > > 'timer' choke causes 2 foot driving when it's really cold out until the > > > engine really warms up. A customer came in Saturday. Engine warm. She said she had to keep her foot on the gas and brake at the same time. Should I change the thermostat to cure the problem?! LOL. What degree do you recomend? Or should I what untill the choke stat timer comes back on?! ROTFLMAO > > >> > I see two problems. First off, with a 180 thermostat in it, you will > > >> > 'always' need to two foot drive until it warms up. [quoted text clipped - 93 lines] > Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 > (More Off Road album links at bottom of the view page) > > > > > > >> > I see two problems. First off, with a 180 thermostat in it, you will > > > >> > 'always' need to two foot drive until it warms up. [quoted text clipped - 7 lines] > thermostat to cure the problem?! LOL. What degree do you recomend? Or > should I what untill the choke stat timer comes back on?! ROTFLMAO You are a total moron aren't you? Besides having no clue about a carburetor, you also apparently cannot read either. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > A customer came in Saturday. Engine warm. She said she had to keep her > foot on the gas and brake at the same time. Should I change the > thermostat to cure the problem?! LOL. What degree do you recomend? Or > should I what untill the choke stat timer comes back on?! ROTFLMAO Simple: you perform the oil change on the RO (strip the drain plug threads, then add 5qts of oil no matter what vehicle) then hand it back to your service writer so a mechanic can fix the drivability complaint. Toyota MDT in MO |
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