No idle this morning (1999 Grand Marquis)

Oct 12, 2007 6 Replies
E

As title says, It would start but die instantly. over & over, unless I kept my foot on the pedal. Did that a while ago, but it started fine on the third try, so I didn't give it any thought other than a fluke...



This morning, Had to drive with both the gas & brake pedal son it wouldn't stall in order to bring it to the mechanic 2 streets from there. Suddenly, a little surge (choke kicking in perhaps?), and of course, it wouldn't do it at the garage (it would've been to easy :)



Tpnight, started fine, but I noticed something, while at stop lights the idle dipped twice.



Friend of mine says MAF or O2 sensor. No codes, no CEL.



On a related note, the Y-Pipe is starting to detach itself from the left catlytic converter (related)



Since winter is coming, I'd like to be able to rely on it, besides, at



60,000Miles, it's a little early to start behaving like my previous POS beater...
Vote
Twitter Facebook LinkedIn
S

Idle Air Control (IAC) valve is dirty/worn, causing dying, erratic idle.

Vote
Twitter Facebook LinkedIn
F

My similar experience (with 97 4.6) was Idle Control Valve. For a picture click the link at the bottom. The part with the egg shaped circle.

THE IDLE CONTROL VALVE

Depending on whom you talk to, this little gadget is called the ISC, BYP, IAB or IAC valve. Whatever you call it, the valve goes bad due to a broken motor or soot buildup from crankcase vapors, usually soot. The answer is to clean the assembly.

-------------------------------------------------------------------------------- Where is it?

On EEC-IV multi-port EFI motors, the idle control valve is located on the throttlebody. The valve has a cylindrical shape with a small wiring harness at one end, with another casting that attaches to the throttlebody.

There are two 5/16th bolts holding the valve to the throttlebody. Disconnect the harness with a small flathead screwdriver and unbolt the valve. Check the gasket that attaches the valve to the throttlebody for any damage or cracks, and replace if necessary.

With the valve in your hand, generously spray light oil such as WD-40, or a throttlebody/carb cleaner in the two bores of the valve. Shake the valve around to ensure the cleaner is moving freely in the bore. If possible, get a length of fuzzy pipe cleaner and use it to scrub the bores to a shine.

Shake the valve until most of the fluid is expelled. Repeat the above procedure if the expelled fluid is extremely dirty. Reattach the gasket, the valve and its wiring harness. You should see a dramatic difference in the idle control of the car.

formatting link

Vote
Twitter Facebook LinkedIn
E

Great... now, it seems to lack power on the low end... (but didn't stall on me yet)

Vote
Twitter Facebook LinkedIn
S

Did you try cleaning it, or did you replace it? In my experience, cleaning them is a lesson in frustration- they may work for a few days or weeks, then the problem returns, or the problem never really went away. For less than $75, it can be replaced with a new Motorcraft one.

Go here to page 151:

formatting link
Your car may have to relearn its idle.

Good luck, SC Tom

Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required