sthacker590

I have 99 Ford Taurus 24 valve v6 dohc. After my car has been running for awhile, the rpms will begin to jump up and down when I come to a stop. Has died several times, engine runs rather rough. Found one vaccum line with a large whole burned in it, seem to run ok after fixed, then it started all over again today. Any ideas about what is going on? I am in desperate need of HELP!!! Any info is greatly appreciated!!
Sherry

shorod

Welcome to the forum!

There are a few rather common issues that could be causing what you are experiencing. If you are pretty certain that there are no other bad vacuum lines, then you may have a faulty DPFE or EGR Position sensor. These are rather common parts to fail. There are numerous threads in this forum related to that sensor, so I'll let you use the search feature to find more info on them.

Another possible problem could be a stuck Exhaust Gas Recirculation (EGR) valve, so that it does not close when your engine comes to idle. Often times if this is the problem, you could remove the EGR valve and clean the passages both of the valve as well as in the upper intake manifold with Throttle Body Cleaner and reinstall.

While you're inspecting the EGR valve, you should pull the air intake hose from the throttle body, manually open the throttle plate, and inspect the back side of the throttle plate and inside the upper intake manifold for carbon build up. If there is a large build up of carbon in the intake or on the throttle plate, the build-up may not be allowing enough air to bypass the throttle plate to keep the car running smoothly. Throttle Body Cleaner will work here too. Do you happen to have a stickly throttle?

You will also want to inspect the spark plugs and spark plug wires. If you have some bad wires, they may be arcing to the engine and causing a misfire.

In addition, if the Mass AirFlow (MAF) sensor elements are dirty (often due to the addition of an oiled air filter such as a K&N) it could cause idle problems in extreme cases. Often times you'll notice a considerable decrease in fuel economy prior to a change in the way the engine idles. There are numerous threads on cleaning the MAF sensor elements (very carefully) so you can search for them as well.

Since you have the 24V engine, you could also have stuck secondary intake runners. If the valves on for the secondaries are stuck open due to a faulty Intake Manifold Runner Control (IMRC) you could experience a rough idle and dieing. I believe on your '99 the IMRC is electrically driven rather than vacuum actuated, so this is probably less likely to be the cause in your case.

Hmmm, that's all I'm thinking of right now. Good luck and keep us informed of your progress.

-Rod

sthacker590

Thanks for all the info. Will try your suggestions and let you know if they work.
-Sherry