1981 240 N/A m46, im driving along and suddenly my oil light comes on. I pull over make sure i have oil and then i start the car only to find its idling at 3500 RMP with out my foot on the gas. I even disconnect the throttle cable and it stays like this. I hear no unusual engine noise other then the intense revving. What could cause this?

I did notice fresh oil on the cap when i opened it. The only the thing i did today was install new headlights, all 4 of them. I cant see how thats related unless im having some kind of electrical issues.

Also, I let the car sit for a few hours and then went to start it, no oil light on but still going nuts with the idle.

You may want to have a close look at your wiring harness.

Bill
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Those who beat their swords into plowshares, will surely plow for those who did not.

Howdy librick,

In regard to the fast idle problem, does the car run like crap when it it is cold but seem to smooth out a bit after a couple of minutes? If so, or even if not, check for a big vacuum leak. Maybe a vacuum hose got dislodged while you were working on it. Just behind the left headlight assembly is the purge canister. It has vacuum lines and fuel lines running to it. I would start my search for a vacuum leak there. Also, check that the intake manifold hasn't loosened at the head. Does the brake pedal get excessively hard? Maybe the check valve on the booster has gone to lunch and taken the vacuum with it. ;-)

No vacuum leak? Check to make sure the throttle plate is returning all the way to it's "home" position. Even if the cable has slack in it, in fact, especially if the cable has slack in it, suspect the throttle plate is sticking open.

As far as your oil light, check the oil level. Check it first thing, before driving the car. If the oil level is low, top it off and start searching for the leak. If the oil level is fine, check the connection of the wire on the sending unit. Follow it back and make sure it isn't touching metal anywhere. A bad connection or frayed wire is the most likely explanation of an intermittent oil light.

Buy and install an oil gauge. It doesn't matter whether it is electric or direct reading. You are not concerned about accuracy. A $15 under dash gauge is probably the best insurance against catastrophic engine failure you can buy. In conjunction with a functional "idiot" light, it can save your engine from death by oil starvation. It just needs to give you a reasonable value. The next time the light comes on, check the oil pressure. If it is down, check the oil level. If you have low or no oil pressure and the the level is OK, you've got a problem with the oil pump.

Leaks can be difficult to pin down; you may want to wash the motor so you can see fresh oil emerging from the gasket or seal involved.

Do not continue to run an engine with little or no oil pressure. Find and remedy the problem or the engine will seize. Replacing the oil pump is relatively inexpensive and a Saturday job. Replacing the engine costs more than the KBB value of the car and is a great deal more involved.

Let us know what you find.

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Mr. Shannon DeWolfe -- (I've taken to using Mr. because my name tends to mislead folks on the WWW. I am a 52 year old fat man

Note that the oil sensor wire goes around the front of the engine, just above the oil pan, where it is subject to oil soaking, insulation flaking, and subsequent grounding. Note that in the course of your headlight work, you could have disturbed this wire.

A couple of other wires go with it inside a flexible (when new) black casing, which is clamped to the front of the engine at two spots. The power to the light comes from inside the car, so a short to ground anywhere along the sensor wire will certainly turn the light on. Therefore, if the light stays on when you remove the sensor wire's connector from the oil pressure sensor, that's a big clue that the wire is shorted. Chances are you will find it easier to replace it with a more sensibly routed wire that to repair the original.

On a K-jet a few years ago, I found the source of a 3000-rpm idle was a faulty temp sensor in a replacement head, which had come from an unreliable source. Removing the snesor connector tamed the beast until I got a new sensor, so that's one way to check if that is your problem. It was the temp sensor for the ECU, not the one for the temperature indicator. It does NOT have a spade lug connector, but one that is trickier to remove.

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jds