The other day my SES light came on and I started getting a bit of a shudder while driving and at idle. Above about 2200 rpm it smooths out somewhat but still feels down on power. Between about 1200 and 1800 rpms if you're under load, like going up a hill, it shudders so bad I'm afraid it's going to throw a rod. It litterally shakes the entire vehicle. If I'm going up an extended hill the SES will start to flash unless I bring the RPMS up out of the zone where the bad shuddering is and then it will go back to steady.

So I took it to the dealership, since I don't have time to mess with it myself. He said it's showing a misfire on #3 and that there was a coolant leak dripping onto the #3 cop and causing it to malfunction. He quoted about $250 to fix the leak and change the #3 cop and plug.

A couple questions. Would one cylider down cause the whole vehicle to shudder so bad? I can see the slight shuddering at idle, but man it's really bad sometimes. More than one cylider out of eight would cause, at least I would think.

Second, does $250 sound reasonable? I was actually thinking it'd be more than that, so I'm happy.

Third, which cylider is #3. I've asked a couple people with differing results. Most seem to be of the opinion that the cyliders are numbered:

Front
1 5
2 6
3 7
4 8

But I also get people that say they alternate like they do on a chevy:
Front
1 2
3 4
5 6
7 8

Thanks all
__________________
Mike
99 Eddie Bauer Expedition
5.4L, AWD, 3.73 LS Rear, Air Suspension

 

Your coolant hose are on the passenger side of the motor and it is a common problem with leaks but it's the 7 and 8 cylinders that it effects. Would ask them to show how coolant is getting to #3. I just fixed a very rough idle problem on my 99, 5.4L Exp by replacing the DPFE sensor. Like you I figured out that the idle was so rough it had to be more than one cylinder misfire causing the problem. No codes on mine.

 

Well I just got it back from the dealer and it was the #4, not 3. Runs like a champ again. Apparently, from what I read on the archives here the coolant leak onto the #4 cop is a fairly common problem. I have yet to look under the hood to figure out exactly what was leaking and what they did, etc. but so far I'm happy with it.

 

As an added bonus my MPG went up almost 2.5 miles per gallon since the fix! Must have been slowly going bad for a while now. I wonder if I replace the rest of the cops & plugs if the milage will go up further.