Several Engine Codes at Once

My 2004 Duratec with 133,000 miles runs perfectly 98% of the time. About a month ago I was driving on the interstate with no problems. I get off at my exit, stopped at a traffic light and the car felt like it was going to stall (it didn't). When the light turned green I took off & it was smooth as silk. The Service Engine light came on.

The Wife and I went to a party, came out about 3 hours later for our 20 mile drive home. The Service Engine light remained on but the car once again ran perfectly.

The next morning I hooked up my Code Scanner. It had 6 codes, PO-351 thru PO-356 which are supposedly Coil related. The car has 1 coil per Spark Plug.

I knew this was out of my league so I took it to a local mechanic who I trust. I didn't tell him I had my own Scanner. He came up with the same 6 Codes & said what I thought "all 6 coils couldn't go bad at once". After further checking he said the Intake Manifold gaskets must be bad & the engine is "sucking air". He said under different temperatures the engine could act differently.

After $300.00 and a month or so later the engine felt like it was going to stall again. Occasionally while accelerating the engine "misses a beat". Most of the time it runs perfectly. Today the Service Engine light came on again. I hooked up the scanner, this time 4 Codes came up. PO-351, 353, 355 & 356.

I took it back to the mechanic, he asked me if I was afraid I would get stuck. The car has never stalled so I told him no. He erased the codes & told me to drive it until the Light comes on again. Naturally, the car is running perfectly. I don't know what to think but I do want it fixed.

Any ideas? Thanks for reading.

If the issue were a vacuum leak due to a bad intake gasket, I'd expect that at a minimum you'd also be getting codes for lean bank 1 and/or 2. Since you are only getting codes for coil primary/secondary issues, I'd be more suspect of the Camshaft Position Sensor (CMP) or wiring issues. Some of the Duratechs had harness issues that I thought caused fuel injector issues, but you may want to look in to the wiring harness issues to see if that also impact the coils.

-Rod

Rod, as always thanks for your response. Would it pay me to replace the Camshaft Position Sensor? I have not spent much money on this car since I bought it (5 years ago with 95,000 miles).

Thanks, Mike

Generally I do not recommend shotgunning parts, but it's probably less expensive for you to buy the CMP sensor and replace it than it would be to pay the diagnostic fee at a shop. It's got to be your call, but shotgunning the CMP is one option. If that doesn't turn out to be the issue, you're not likely going to be ahead in the long run as the CMP is not necessarily a maintenance item that will fail.

-Rod

Someone had informed me about the "Engineering Test Mode". Here is what happened to me today with this new knowledge.

A January day in late October. Rainy, occasional slush & down right chilly. I went to visit my Dad in the hospital. With weather like today the defroster (which runs the AC compressor), rear defroster, headlights, wipers, CD player were all on. As big a drain as you could possibly have on your battery.

The car starts up fine & is running fine as usual. I noticed as I came to a stop the CD player shut off for a second or 2. This get more & more frequent during this 5 mile ride. The car actually hesitated when I accelerated after stopping at a traffic light. I got to my destination, turned the engine off then got it into the Engineering Test Mode (ETM). The battery at rest registered 12.1 Volts. I started the car & stayed in the ETM and I had 14.3 Volts.

When I left the hospital (about 1 1/2 hours later), I had the bright idea of driving the car home in the ETM. I had it set on battery.

When just driving along at 30 MPH the Voltage maintained 14.3 Volts +/-. When coming to a stop the Voltage was all over the place (11.6 to 14.3). At one time the CD Player went off the Voltage was 10.9. The car has always had a very low idle speed, about 600 RPM's in drive when warm. Between 800 to 1000 RPM's in Park. When the Voltage dropped to 10.9 I thought the car was going to stall. I hit the gas a little with my foot on the brake, I was at about 1000 RPM's and back to 14.3 Volts.

Does this mean the Alternator/Regulator is going bad? I have not had a chance to go to Autozone yet to get the charging system checked.

Has anyone come across anything like this before? Any help would be appreciated. Thanks!!

I'm now kicking myself for not suggesting you check the battery earlier. I had a somewhat similar issue on my wife's 2002 Lincoln LS. It seemed about 2 mornings per week she'd start the car in the morning, back down the driveway, and when she'd step on the brake to shift from reverse to drive, the car would stall. I tried a tune up, confirmed the fuel pressure was good, checked for vacuum leaks, etc. No change. Then through reading on Automotive Forums I started to read about several oddities happening on those cars due to low batteries. Even though the battery in her car was only 3 years old at the time, I decided to swap it with a a new one. Sure enough, that strange stalling went away. I suspect after sitting overnight, then starting the car it dropped the battery down just enough that when pressing on the brake pedal it brought the system voltage below that threshhold for the computer to clearly know what it was doing.

It sounds like your alternator and regulator are working to me, but that your battery is weak and not able to supply sustained and instantaneous loads well. The alternator isn't designed to sustain large draws when the engine is at idle, that's the battery's job. I'd suggest starting with the battery.

-Rod

Thanks Rod, I'll let you know what happens. I hope that is the problem, maybe we can help someone in the future.

Checked with Hydrometer, all cells even & at full strength.

Tested with Volt meter, reading 12.35 at rest. Started car voltage read 14.1.

Drove car to Advance Auto, car ran horribly. Voltage varied from 11.1 to 14.3, radio went off (a second or 2) when voltage was low. Car never stalled.

Advance tested Battery: Voltage 12.55U, 630 CCA, rated 650 CCA, temperature 63 Degrees. Battery meets or exceeds required standards.

Starter Test: Results Cranking Normal, Voltage 10.33U, Amps 0.0 A, Time 812mS.

Charging Test: Results No Problems, No Load 14.37U, Loaded 14.30U.
Charging System Output Test Normal.

After Advance telling me everything was fine I decided to buy a Battery anyway. I took the sparkling clean terminals off, cleaned them again & installed the new Battery.

I took the car for a 3 mile test drive with the AC, Rear Defroster & Radio on. It was in the Engineering Test Mode. While running (perfectly) the Voltage was 14.0, when I stopped at a traffic light the lowest it went to was 12.6 Volts.

Now, only time will tell. As I said the car ran horribly before I replaced the Battery & perfectly after. We shall see.

I will post back if anything changes.

I've seen those automated charging system tests test faulty batteries as good on at least two occasions (and that's probably 40% of the tests I've seen).

-Rod