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Define "kills spark plugs"? If they foul fast, their heat range maybe too cold not allowing them to burn off deposits. Be careful tampering with specified heat ranges as you can damage pistons. Are the new plugs the exact replacement part for that engine? I have switched brands of of spark plugs and have gotten "exact replacements" that were the wrong heat range. For me, I try to stick with the brand used at the factory where ever possible. This way, if it's wrong, it's THEIR fault. Colder range plugs will work fine but for much less time. Another thought. Does this have an automatic choke or a manual choke that you have to close and open? If it's manual, close it to start, open it part way to get going. Open it all the way in about a minute to run. If you run it with the choke shut too long, your fuel mixture will be way too rich once the engine warms up, in turn, fouling your spark plugs. If the choke is automatic, take the air cleaner off and look down the throat of the carburetor. When cold, the plate should be closed all the way. Start the engine and watch this plate. If it doesn't open within 1 or 2 minutes at the most, it's thermostatic actuator is either stuck, malfunctioning or not reacting to engine heat as it should. This will cause spark plug fouling in a hurry. A cold engine requires more fuel to run properly. Rather than try to make a carburetor that will deliver variable amounts of fuel according to ambient air temperature, It is much easier and cheaper to temporarily restrict the amount of available air with a choke plate to achieve this goal. If this choke stays closed for too long or if it is jammed shut, What is the right amount of fuel in a cold engine becomes way too much fuel once it warms up.This is the way that carburetors have worked for over 100 years. Good luck.
Another thing that can cause this is the carb. It may be getting too much fuel once it's warmed up. An engine needs more fuel when it's cold than it does when it's warm. Cold engines run inefficiently so they need more raw fuel to fire-up, and stay running. This is all a choke does. A choke plate closes-off the air going into the carb which makes the fuel mixture really rich so it can run. Less air = more fuel. You'll also notice that cars with chokes also idle real high until they warm-up. This fast idle and the over rich mixture (due to lack of air), allows the engine to fire up and stay running. As the engine warms-up and starts burning fuel more efficiently, the choke plate begins to open, which slowly lets more air in and leans-out the air/fuel mixture. Once the engine is warmed-up, the choke plate will be wide open allowing the carb to run as it is supposed to with the correct metering of fuel and air.
Hope you had an earlier answer for this problem. The air sound could be the air suspension running after a long time of sitting inactive. As for choking, it does not quite describe how the fuel enrichment system works. The "cold start sequence" is suppose to increase the idle speed and enrichen the fuel ratio until the engine warms up.
If the engine speed is low on start-up, the cold start sequence is not working. The water temperature sensor gives the cue for this system to work. Low antifreeze levels or dirty or defective temperature sensors can affect this. Some vehicles have 2 sensors with 1 operating dash gauges and the other the engine controls. A few sensors operate off of manifold heat without making contact with antifreeze.
There is also the possibility of water in the fuel through condensation similar to a pop bottle sweating. Use 1 or 2 bottles of a product called "HEET" into the gas tank and start the car. You will see clouds of vapor coming from the exhaust if the water was present.
hello wyatt......
Is your jag.built with a carburetor or fuel injected? Carb, your choke is not set to close when cold, and should be set. When set, it also sets a cam that keeps the engine running fast. Then when warm, you hit the pedal and the cam moves, and the engine speed goes to normal. Unless the choke is set, the engine cannot keep running, as it tries to run on cold gas and it can't run good on cold gas. It needs more gas, therefore, and the choke makes more gas go into the engine.
Fuel Injected, the computer should adjust the amount of gas your car is getting when cold. If not, the coolant sensor might be bad. The coolant sensor senses the cold engine and tells the computer to add more gas. Once the engine is warm, the coolant sensor tells the computer to put the gas to normal. So, if the sensor is not working, the engine will try to run normal, and if cold, it can't.
Joe
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Here are some images that might help to assist you, and let me know if you require any further assistance.
Adjust the curb idle with the engine warmed up and the choke off.
The air/fuel mixture screws should be adjusted with the engine warmed up and at normal idle speed, then turn each air/fuel mixture screw in one at a time until the engine just begins to mis-fire, then back the air/fuel mixture screw out 1-1/2 to 2 turns out a half a turn at a time until the engine idle is the smoothest. (your vehicle might have restrictor caps over the air/fuel mixture screws to limit the amount of adjustment)
The choke adjustments;
To adjust the vacuum tension pull on the choke pull-off:
Adjust the fast idle screw to the proper RPM with the engine cold and the choke on.
It sounds like your IAC,idle air control,this unit controls your idle once your choke completally shuts off.on 2.8litre it is located right side of engine just above where your fuel lines go into your manifold ( fuel rails), it's held in by 2 screws &looks like a little electric motor, it's actually a soliniod, inside is a little pinnacle that goes in and out and is controled by the computer.good luck.
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