Rough idle?

[CZSteve]

Wife's car is a '98 Mercury Mountaineer 5.0 2WD.

The car began exibiting the 'chirp' coming from the front of the engine.

Appeared to be the drive unit for the cam position sensor.
Based upon a comment here, I decided to try a stop gap by pulling the sensor and spraying white lythium grease down drive unit.

The CMP sensor looked terrble, the magnet was rusty and a bit loose in the plastic housing. I re-assembled everything and upon starting the idle was quite rough.

Figured it was the sensor and a result of my disturbng it when I removed it.
Put a new sensor in from NAPA and the idle is STILL rough.

I've checked the plug connections and everything seems good.
The drive unit was never pulled or rotated, I just removed/replaced the cam position sensor.

BTW the 'chirp' is gone at least (for now)

Any thoughts?

Thanks in advance.
Steve

 

[Turdle]

Did you recheck vacuum lines. Check under the upper intake plennum, there is one there that could get knocked off. If the wiring to the sensor was bad you'd get a CEL for sure, and it would idle ok if it was bumped out of adjustment. I think a vacuum line got bumped when you messed with the sensor the first time.
Are you sure you didn't rotate the housing at all?
This is a fuel injector timing signal, it should be adjusted correctly

 

[exploded99]

I am not sure at all that this will correct your issue, but disconnect the battery for 15 minutes to reset the computer. This will restore the PCM to default settings and erase any "learned" idle behavior.

 

[ExplorerDMB]

Some sensors are VERy sensitive and if they are moved a little or even have the wrong air gap can be worthless. Make sure you did everthing to specification.

-Drew

 

[CZSteve]

I'm going to recheck the vacuum lines on Thur and the weekend, lack of daylight in the evening makes it tough after work.

I already disconnected the battery for about fifteen minutes to reset, no help.

I'm 100% positive I did not rotate the drive unit. Never even touched the hold down clamp.
But, it's idling like the timing is off ever so slightly.
The wife drove it today to work, short drive - right or wrong.
It will maintain idle in gear, even with the a/c compressor engaged - just feels like it's on the verge of dyeing.

Still welcome to any thoughts.
BTW: I know this isn't proper procedure. But, is it possible to increase the idle about 50-100 rpm's?
Is their an idle set screw in these fuel injections engines?

BBTW: Can a shop check if the the cam position sensor's timing is off?
I'm use to the old day's - hook-up the timing light and re-adjust the distributer.