2000 Ford Taurus engine revs and loses power

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  • 2000 FORD TAURUS

Engine Performance problem
2000 Ford Taurus 6 cyl Front Wheel Drive Automatic 140000 miles

Hello hopefully you can help me. I have asked different people and have gotten different answers. A couple months ago I noticed that my car would rev at all times while idleing. When I looked under the hood I noticed a foam piece connector was burned by hot oil (the connector connects the tube to the engine oil fill tank and I'm not sure of what it's called that the other end goes into). It was leaking some oil due this piece. I didn't buy the actual piece to fix it but I did get a temporary connector to hold it together for now. No oil leaking since then. The reving seemed to have stopped. About a week later the reving started again but only when I have my air on. I also noticed that while driving (at different speeds) I can take my car off the gas and it feels as if the brakes are being hit as the car roughly pulls back and then slows itself down quickly. If I go to press the gas again it hesitates before kicking in to pick up speed. There has been no check engine light on at all and when a computer diagnostics was done it showed no code. Some corrosion on one of the battery cables and the battery hasn't been changed for awhile. Not sure how old the alternator is. There is no other 'electrical like' problems with the car (i.E. Lights dimming, etc.) Please Help!

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Thursday, April 22nd, 2010 AT 11:35 AM

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The tube that you repaired is the oil filler neck ventilation tube. As you noticed, it resides between your valve cover (where the oil cap is) and your air intake.

If you noticed oil at the air intake/throttle body end of the hose, a little oil may have entered your throttle body and fouled your Intake Air Temperature sensor, or clogged up your Idle Air Control valve. To quickly check your IAT, remove your air intake from the throttle body (the intake may look like a stretched accordian on your car, or just a large hose coming from your air filter housing), and peer into the open hose. There should be a sensor poking into the air tunnel. Check for any greasy residue on it, and if needed, spray with it with a little non-chlorinated brake parts cleaner. A very dirty IAT sensor would cause a moderate amount of idle and driving problems.

The IAC is a module that is bolted onto your throttle body, and greatly effects the air getting to the engine. A fouled IAC will give you a rough idle, or if stuck open, could cause you to idle high. You can unbolt it from the throttle body and check inside to see if it is fouled. Bear in mind, even a small amount of black residue can indicate a clogged mechanism. Brake parts cleaner can only go so far with this part, so if you determine that this is the problem, you may have to replace it.

Further, a leak in the OFNV tube can cause a few crankcase pressure related problems, including:

Positive Crankcase Ventilation valves getting blown out, which would likely lead to vacuum leak behavior (which your driving problems indicate). The PCV valve is attached to a vacuum hose. Look around the rear of your engine; you may have a vacuum hose loose (or dangling) from it's nipple. If so, slide it back on.

With the OFNV tube disconnected, you can also stress seals in your engine. You will be looking at other things before worrying about this.

If the OFNV tube still doesn't have a tight seal, it could be causing a (slight) vacuum leak. Since your problems strongly indicate a vacuum leak, I would replace the tube.

Any hissing coming from your engine compartment will mean a major vacuum leak. The usual suspects for a vacuum leak are the emissions modules at the rear of the engine, at the break booster (right next to your brake pedal. You should be able to hear a hiss in the passenger compartment), or at your air conditioning vacuum supply hose. If you find a hissing hose, or even brittle cracked hose, replace it.

Just below your upper intake manifold (which probably looks like branching tubes that curve down into your engine), is the lower intake manifold. It has a gasket that runs all the way around your engine, and this seal is another place you can find an air leak.

Attention: Keep a fire extinguisher around for this part.

You can (carefully, and without wearing loose clothing or dangling jewelry), with the engine running, spray starting fluid at the seam where the lower intake manifold meets the rest of the engine. If the engine idle sound changes, you have found a gasket leak. You may wish to do this for the upper intake manifold gasket-seam also, though I have never personally run into a (noticeable) leak there.

If you find a leak in your gaskets, you will have to take the upper and (possibly) lower intake manifold off to change it. Get a maintenance manual from your parts store if you want to do it yourself, otherwise, call a shop.

Since you said your main problems happened when you are using air (and thus the vacuum supply to the a/c), I would suspect a combination of a small vacuum leak and fouled sensors.

Finally: Do you have a check engine light yet? An injector, ignition, or sensor problem usually turns it on if the oxygen sensors in the exhaust notice bad fuel/air conditions. Contact your local Autozone about reading your OBDII system; sometimes there are codes that don't light your dash up. Heck, your check engine light bulb may even be out!

Good luck!

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Sunday, May 2nd, 2010 AT 1:32 AM

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