'04 Taurus rough running

[NMBurb02]

I have helped out a friend with his 2004 Ford Taurus SES over the past few months due to it having a rough idle, hesitation, and check engine lights. So far, we've replaced the spark plugs (got rid of the first CEL), cleaned the MAF sensor and throttle plate, replaced the cabin air filter and engine air filter, and replaced the spark plug wires (second CEL).

Today he texted me the following:

The car has been somewhat rough lately. Not as bad as when the spark plug needed replacing but still enough to make me uncomfortable.
It only happens when the ac is on and usually when the engine is cold - though it does happen at times when the engine is warm.
Going up a hill and a cold start are when it happens most frequently. If AC is off - no issues.
I was reading online and someone suggested to change the idle air control valve.
I tried that this morning and no dice.
Then, usually when it's real hot out, when the ac is on and I start it up there's a loud squeal until I get the car going. If the ac is off, no squeal."

Much of the A/C system was replaced within the last year or two (compressor, condenser, and most refrigerant carrying lines, I believe). I'm thinking the A/C compressor is low on oil and the A/C compressor clutch is dragging, causing the rough running and belt squealing only when the A/C is on. Am I far off? If that is most likely the problem, is it pretty easy to replace the compressor oil in a Vulcan V6?

 

[bdcardinal]

Check motor mounts. Also it is not unheard of for the heads to drop a valve seat on the Vulcan motors.

 

[NMBurb02]

Originally Posted By: bdcardinal
Check motor mounts. Also it is not unheard of for the heads to drop a valve seat on the Vulcan motors.

How does that explain the belt squeal?

BTW, the second paragraph was the texts from my friend. The last paragraph was mine. I meant to close the italics at the end of the second paragraph but forgot and it is now too late to edit.

 

[yonyon]

Originally Posted By: NMBurb02
Originally Posted By: bdcardinal
Check motor mounts. Also it is not unheard of for the heads to drop a valve seat on the Vulcan motors.

How does that explain the belt squeal?

It doesn't. It very well may explain the vibration. Okay, dropping a valve seat would give you both, but motor mounts wouldn't. Sometimes a car has more than one problem. Have you replaced the belt or measured the grooves with a belt wear gauge recently?

 

[Barkleymut]

could be a number of things, PCV, egr, ignition coil, etc.

 

[NMBurb02]

If it is a motor mount, dropped valve seat, belt, PCV, EGR, and/or ignition coil, why are the issues only encountered while the A/C is running?

 

[yonyon]

The A/C increases load (compressor and alternator) without raising the idle speed by much.

 

[Warstud]

I wonder if the newish compressor was installed dry?

 

[crazyoildude]

what are the codes?

 

[NMBurb02]

Originally Posted By: crazyoildude
what are the codes?

No codes now and don't remember the specific numbers, but all four were for misfires. The plugs and wires were replaced about a month apart. Each time there were codes, there was one for a misfire in a specific cylinder and another for misfire within first 1,000 rotations. I believe the first CEL was for cylinder 3 (plugs) and the second for cylinder 2 (wires - one was burned through).

 

[NMBurb02]

Originally Posted By: Warstud
I wonder if the newish compressor was installed dry?

I was thinking it might have been shipped low and it wasn't checked/topped off by the installing shop.

 

[bdcardinal]

I missed the squeal part. If there is a new belt and the squeal is still there then it is the cam synchronizer.

 

[SuperDave456]

I have a 2002 Ford Taurus with the 3.0 Vulcan also, I just went through something similar.

Replace the Power Pack with one from Denso, NAPA has them. They are expensive, but they should last around 100,000 miles.

I replaced mine with plugs using a Autozone Duralast part 2.5 years ago. It just failed.
Not a lifetime warranty on the part, 2.5 years ago the power pack only carried a 2 year warranty.
I told AZ they could keep my part, and I went to NAPA to get the OEM Denso part.
Did the wires too, as the Autozone Boch ones that I bought had clips that broke as soon as I pulled them off.

It won't throw codes till the idle gets REALLY rough and the Power Pack dies completely.

I'm really disappointed with AZ. 2nd part to fail and strand me in the past year.
I had a brake light sensor die on me at a job interview, I couldn't leave the parking lot till I had that fixed.
I've really started to hate that place.