I have a problem with a 2002 Mercury sable. At idle and under acceleration, it has a miss, it’s worse when cold then improves when it’s warm but never goes away and almost seems to come and go when driving. It’s definitely worse going slow or idling. The check engine light is also on, I scanned the codes and it came up with 4 cylinders misfiring. codes were p0301 p0302 p0303 p0305 p0316 to be specific. I changed the spark plugs last weekend, how it ran at all is something I’ll never understand they were so bad, obviously original with 150,000 miles on the engine. It’s a little better now but not much. Does anyone know where I should look next? I’ve been told a lot of things but I can’t keep throwing money at this, I’m unemployed so really the next major attempt is probably the last. Anything I should try? If it was carburated with the old distributer I’d have this fixed in no time but fuel injection and computers, coil packs, all totally new to me. No white smoke out the exhaust, no funny noises just a miss and check engine light with only the codes above. Thanks.
@JohnM80 this might be for you.
Updating the PCM software might cost you a c note, but not much more, as it’s a relatively simple procedure for a dealer.
I would thoroughly check out the battery and charging system, as per the TSB
Replace the battery if it’s more than 5 years old.
There are several other possibilities, but I don’t want to go overboard.
In my opinion, spending a c note on a software flash because of a known TSB (for which you actually have the symptoms) is not an act of desperation. I also wouldn’t call it guessing.
Without being there and troubleshooting for myself, my best guess would be the coil packs. Normally the coil packs would last the life of the car, but the newer coil packs are epoxy filled instead of oil filled. Every time the spark plug misfires, the voltage has to go somewhere and generally arcs from turn to turn arc inside the coil. The old oil filled coils were self healing because the oil was fluid, but since oil is not as good of an insulator as epoxy, the coils had to be big.
The epoxy coils can withstand very high voltages for short periods of time, but eventually the epoxy begins to break down, and when it does, the coil stops working. In other words, the smoke gets out, and coils don’t work without the smoke inside them. You may even see some little burn holes where the smoke escaped. Smoke is like a cat, once it gets out, you can’t put it back in.
@Keith as far as I know, that car has one single coil pack
It may be one module but it looks like three separate coils for a lost spark ignition. I suspect two of the coils are bad. Looks like he will have to get one of these and that will replace all the coils.
@JohnM80, here’s another one for your consideration. It amounts to the same thing: reprogram the PCM.
If I’m reading the first PCM reprogramming article, it mentions a battery discharge code, the codes I posted are the only codes I get which is the cylinder misfire, coil pack thing makes more sense to me. That’s what I suspected from the get go but it seems like almost everyone I know discourages that idea and where the spark plugs I took out last week had almost no electrode left at all and because of it were gapped at more than double what they were supposed to be, and I never knew until shortly before, it does suggest to me what was said about the coil packs over working. And yes, you replace one you replace them all, it’s in a 6 pack configuration on a single block so replacing it is all or nothing. Probably the easiest thing I’ll have replaced on this car. If anyone else has ideas let me know, or any reason I should try something else, other wise I’m going out in a couple hours anyway so I may make a quick stop at the parts store and grab one.
witch v6 do you have?
the ohv uses 1 coil for the whole eng. and the dohc has 6 coil packs. if its the ohv when was the wires last replaced?
It’s the OHV engine. The plug wires were replaced a year ago when I had other work done on the car under warranty, I bought it used with a warranty but I’m not sure if he used new wires or decent ones he had sitting around so I just got brand new wires now though what’s there looks fine. I’ll change the coil pack and wires and see what that does. It would be so nice if I was on the right track here.
@JohnM80 if you look at that first TSB I sent you, it states that you may have one or both of the conditions. While you may not have a battery problem, you definitely have those exact misfire codes that are being referred to.
Either way, you’ll be out about a c-note, whether you do the coil pack or get the PCM reprogrammed.
If you do the coil pack, tackle it yourself. It’s pretty simple.
I replaced the coil pack, that improved it a bit, then I noticed a lot of brap on the spark plugs when I took the plug wires off them, right where the plug wires connect so we took a good look and I guess when the plug wires were replaced a year ago, they were not new. They are now and that made the rest of the difference.