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Discussion Starter · #1 ·
My 2004 Sable Duratec DOHC is still acting bad after well over a month of trying to figure it out. Engine was/is missing without showing any codes. All started in July with the misfires. Then out of nowhere my Alternator needed to be replaced in early August. I posted about this in August and received a bunch of very good suggestions and advice.
Misfiring w/o codes

Anyway here’s what’s still been happening:
The car starts out great and runs with no problems for about 4 miles. Then it will start missing which gets worse as it goes on. Rough idle and hesitation on acceleration. If the A/C is on, turning it off makes the issue a little better but not totally.

In addition, after a while the “Check Battery” warning and light will come on. When I monitor with the scanner plugged in, I can see the battery voltage drop down to around 12.1v and then to slightly below 12v. This will last for a few minutes until voltage starts rising again up to 14v and “Check Battery” light goes out again.
Engine will continue to miss until it sits for a while and completely cools down. Then the same scenario starts all over.

Over the last month, besides the alternator I replaced all six plugs, put in 2 new coil packs (all 3 rear ones are now new) replaced upper and lower manifold gaskets, EGR gaskets, air intake gasket, pulled and checked PCV valve and hose, cleaned battery cables and connectors, cleaned the ground connections on the fender by the battery, and under the cowl by the PCM, pulled the PCM and checked for continuities, replaced all associated fuses and pulled cleaned and reset all remaining fuses and relays in the engine compartment, replaced any related fuses in the cabin and found and cleaned the ground connection there.

The car hasn’t died on me since the alternator was replaced and always starts right up, so that's good. As I said, the engine runs great until it warms up. Then all this starts.
 

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My '05 DOHC when bought had misfire only when hot. Pending code was #3. Used coil from JY fixed the issue, 1.5 years later all is OK.
My '04 Sable DOHC new battery, cleaned terminals. Daughter borrowed it (traded cars). Friday night, she calls and no lights. At gas station nothing working.
Jumped and started. I took the car back. Took battery out and battery box and checked wires, all good. Today, sitting in my drive way, all dead. With only the door open volts at port 11.0, battery terminals 12.3. Loss between negative battery cable and the frame. Cut the insulation off at the cable end and corrosion under the insulation out of sight. The loss of charging could be bad grounds. Grounds to the body Ford clamps eyelets over paint. Pic of firewall ground making for bad idle. The big eyelet is the primary current from the Alt to the body.
-chart-
 

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2003 Taurus SE, 2019 Sonata SE, 2022 Kia Forte LXS
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I wonder if you are using a powerful enough scan too. The cheap ones have limited usefulness.

Go to an AutoZone or O'Reilly where you can get a free code scan with a professional level scanner.
 

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Discussion Starter · #4 ·
My '05 DOHC when bought had misfire only when hot. Pending code was #3. Used coil from JY fixed the issue, 1.5 years later all is OK.
My '04 Sable DOHC new battery, cleaned terminals. Daughter borrowed it (traded cars). Friday night, she calls and no lights. At gas station nothing working.
Jumped and started. I took the car back. Took battery out and battery box and checked wires, all good. Today, sitting in my drive way, all dead. With only the door open volts at port 11.0, battery terminals 12.3. Loss between negative battery cable and the frame. Cut the insulation off at the cable end and corrosion under the insulation out of sight. The loss of charging could be bad grounds. Grounds to the body Ford clamps eyelets over paint. Pic of firewall ground making for bad idle. The big eyelet is the primary current from the Alt to the body.
-chart-
Electrical problems are the worse. I took a wire brush to the ground connections in your photo, and the one on the fender next to battery. Neither one had much corrosion, but I scraped the paint off and cleaned them. Are there any other ground points like that I can get to?
 

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Electrical problems are the worse. I took a wire brush to the ground connections in your photo, and the one on the fender next to battery. Neither one had much corrosion, but I scraped the paint off and cleaned them. Are there any other ground points like that I can get to?
There are two. When the engine is not running: primary is to the fender, when running (Alt charging) primary ground/current is to the firewall. TEST: Key on, not started. Climate blower max, HL on. Measure volts loss between the negative battery post and a cleaned place on the fender. 100mv = 0.1V is the the max acceptable. 50mv is good. In the pic I added a secondary ground strap. This car had 140mv and that is added security, and, I had the strap in my wire box. This car from 140 to 25. My case is, it will always get worse with time. In the pic, I remove the covering of the ground clamp as in the pic, and see this if without corrosion.
Short story, different car, recent buy. '04 Sable wagon. Daughter borrowed it, stopped to get gas and it has no crank. I took the Taurus and battery jumpers and jumped and it started and ran fine. I took it home and since at night left it sit. Next day, dead but battery 12.3V. Under that ground covering, the wire had corroded through at the clamp. I had to cut the covering off to see that. So there is no reason to cover the ground, and it limits the chance to see corrosion, and likely makes corrosion worse.
And good reason to jump with the negative to the engine and not the battery. This bypasses the car ground for the jumper current.
-chart-
 

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You still have the charging problem.

In the 2004 model the PCM regulates the alternator. You might double-check whether the 3 pin connector at the alternator really has all three wires connected (earlier models like my 2000 Vulcan only have the 2 outer wires connected).

I assume your alternator is OK since you replaced it with a new one from O'Reilly's (correct 2004 model too).

Although this sounds far-fetched, you cannot rule out it is the PCM. Either the PCM is broken (no scan tool will report: "I'm broken, replaced me"). Or it is the wrong PCM. How long do you have the car? Is it possible somebody replaced the PCM?

You could check the part-number on the PCM with the compatible part-numbers Flagship One mentions on its website for your 2004 Duratec. You might consider replacing the PCM. A replacement PCM is not much more expensive than a new alternator.
 
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