My Taurus has died twice this week while idling. It seemed that the A/C compressor kicked on just as it died. Im not sure what to check, so any help will be greatly appreciated.

 

There are several paths one might pursue ,one of which is ,
The available electric power to the components.
If the battery and cable connections are not clean and tight there is resistance in the system and when a considerable load like the air conditioning compressor is turned on the available power drops and it drops low enough for the vehicle's computer to shut down and the engine quits running due to lack of fuel control. So, a good place to start checking would be all the ground connections and battery cables. Once that is confirmed you can move on to other possible areas.
When an additional load is placed on the engine the computer is made aware of the load request and adjusts the idle speed accordingly. At higher engine speeds the charging system may make up for the powerdrop and the problem may not be present.

 

The battery terminals are clean and tight. I filled up with gas yesterday and the car was running rough like it had water in it or something. It was fine until then but after, it was bucking again. I then realized that the last time it shut off was right after filling it up. I use the same station every time. Is it possible to have some water in the tank, and when I fill it up it mixes with the gas for a while and causes rough running. This morning after sitting over night it ran just fine with no bucking or cutting out. Oh and when it is runnning rough the tach never drops.

 

I kinda doubt there is a water in the fuel problem, but what I would suspect is that there is a problem in the Evap system. When putting fuel in the tank vapors are supposed to be able to exit out through the charcoal canister where they get trapped only to be removed later to get burned in the engine. At that time a vent valve is supposed to open and allow the pressure to escape . If it sticks open or the valve sticks open that opens to allow the canister to be purged, can result in a rough running idle or cause an overrich condition because the engine vacuum system is constantly purging when it should only be purging when certain conditions are met. A good possibility one of those valves is malfunctioning.

 

Last week I had a code for the purge valve open circuit. I checked the connector, cleaned it and put it back together. I didn't clear the code because I wanted to see if that fixed it or not. After about three days the code cleared itself and I haven't recieved a new CEL. Last weekend when it started acting up again the CEL wasn't on and it still hasn't come back on. It was surging a couple of weeks ago and I found a vacuum hose off that must have come loose when I was changing plugs. I put it back on and it did seem to help. I can't find another hose off but it is getting worse than it was before. I am baffled as to what to do. It has 224,000 miles on it now and maybe it is just time for it to go but it runs fine until this surging starts. It seems to get worse while going uphill though when the engine is under more stress. I didn't change the plug wires when I put in new plugs, and was wondering if the plug wires could cause this surging thing? I hope I don't have to put it in the shop because they are up to about 80 dollars an hour for labor. I cant afford to pay much for them to trouble shoot it. I can do most of the checking myself if I only knew what to check. Thanks for all your help.

 

Just a little something you might try.
If you remove the intake hose from the throttle body you should see the throttle butterfly. With the engine not running if you look at the butterfly and it looks cruddy and dirty try cleaning it with a rag and a little throttle body cleaner. Many times it takes care of many problems that do not turn on the check engine light.

 

I took a look, and the butterfly was extremely dirty. I cleaned it up with carb cleaner and a rag. I also cleaned the carbon build up in the IAC valve. It was pretty bad too. I did notice that the Tach is now moving back and forth between 6000 and 8000 RPMs. I drove the car about 200 miles since cleaning the butterfly and so far it hasn't surged or bucked anymore. It hasn't died while idling anymore but the Tach fluctuating has me baffled. Any Ideas? Thanks in advance for all you do.

 

The tach gets it's info from the crank sensor and the PCM. Things like electrical gauges can do strange things when poor grounds are involved. I believe we suggested checking all the body ground connections and if that was not done it is a good start to rule out something simple. After that some more detailed checking will be in order.

 

Today the CEL came on. I took it in and the store manager said it was a P-1235 code. The car started surging again just like before but it hasn't died yet. Any idea as to what to check? Thanks in advance. I have checked all the grounds I can find but maybe i missed one. Also the radio has started going silent periodically. It stays on and everything looks the same, except there is no sound coming out of the speakers. Any help on that would be appreciated. Thanks

 

Update, The CEL went out on its own. The car is still surging though. Any ideas will be greatly appreciated.