Can a faulty injector cause the P0301 scan code?

The vehicle is a 2002 Ford Windstar van with a 3.8L V-6 engine. It has a constant miss on the #1 cylinder. That’s the one on the backside of the V-6 on the passenger end of the engine. I have changed the plug(s) and still had the miss and P0301 code. The plug’s wire has about 7500 Ohms, so it’s not the problem. I hear no snapping of a high voltage short to ground. A friend suggested that the injector might be the issue, but I am of the opinion that the scan code shows only a high tension or secondary ignition system issue, and not fuel injection issues. I’m thinking the problem is more likely to be the coil pack.

What is the opinion of the group.

I dont think that code is specific about why there is a misfire or not…I have to research that. I would see if that wire has spark…by the usual methods… No spark? Then start down that road. However you can get a misfire from no fuel as well.

You could have a bad injector or a faulty coil or wire or plug… The spark side of things is easy to diagnose…so I wont go into that but the injector is a little more tricky. I guess figure out which situation you are facing…its one or the other usually.

You can check your fuel injector by listening for the injector clicking while the engine is running. I have a mechanics stethascope for this but a long screwdriver does the trick also. See if you get a clicking sound similar to the known working injectors noises. If not…test for batt voltage on one of the injectors wires. The other side is pulsed by the engine ECU…it sends pulsed ground signals to each injector once it gets the go ahead by either the cam sensor or the crank…whichever way Ford set this system up. A “Noid” light is nice to have in these cases. Once you find batt voltage on one of those injector wires its now up to the ground pulse to fire that injector…no pulse…no fire. I have found the injector systems to be pretty solid in reliability…

I have had injectors simply go bad or maybe sometimes they have a particle of dirt stuck in them… Again listening to the injector is a big help. Whenever I think an injector is stuck I ground out the negative side of the injector WHILE the harness is plugged in…this will hold that injector OPEN…and dislodge any particle that might be holding it open…works a lot of the time actually.

See if you need a new injector…or have a spark issue and you will be on the road again in no time.

Blackbird

P0301 simply means that cylinder #1 is not firing properly. Spark plug, wire, coil pack, fuel injector, vacuum leak, mechanical problem, etc, all can cause this code.

Forget about the fault codes and just go about diagnosing it as you would have before OBD2. Check spark, check mechanical, check fuel delivery.

Of course since it is OBD2 your scan data will tell you whether you’re looking at an ignition, fuel, or mechanical issue so you’ll have a direction to start.

Does it misfire constantly or just under a load when driving?

Yes a defective injector not injecting fuel can cause a P301 code.

However, anything that would cause cylinder #1 to not contribute to the crank rotation would set a P301 code. When the ECM sets the P301 DTC, it is saying that cylinder #1 did not show a torque pulse on the Crankshaft Position Sensor. The items that should be looked at for this DTC are spark, compression, fuel, valve timing, spark timing, fuel injection timing, etc. Anything that would cause a one cylinder engine to not run should be examined. Therefore, you should check that the spark is present and healthy; check the compression; make sure that the valves are openning and closing; check the TDC spark timing for #1; etc. As Blackbird suggested, check that you can hear the injector armature click with each injection cycle.

Hope this hellps.

Quoting @researcher

“When the ECM sets the P301 DTC, it is saying that cylinder #1 did not show a torque pulse on the Crankshaft Position Sensor.”

There’s there part I didn’t understand. Now I have some better direction to look into.

Thanks

I would start by doing a compression test on the motor to rule out a mechanical problem.

"#1 did not show a torque pulse on the Crankshaft Position Sensor" ... Now I have some better direction to look into

Yes, that means there’s occasionally (or always) no big explosion happening inside that cylinder for some reason, at the time there should be.

So what makes an explosion? Fuel & air of the right ratio. Enough compression. Spark at the right time. Blammo!!! Since you got no Blammo, something is amiss with at least one of those things.

If it was a fuel injector not injecting, you’d expect you might see a problem in the O2 sensor as well, as there’d be lots of unburned O2 hitting that exhaust sensor. And you might see a problem in the fuel trim, as the computer would try to compensate for the extra O2 in the exhaust steam by injecting more gas.

At the end of the day who cares? You need to see if you have Both Spark and Fuel. Spark can be figured out in about 5 seconds… Fuel…a little more difficult.

Blackbird

I definitely have no spark on the #1 cylinder. Since the plug is new, and the wire ohms out good, I now suspect the coil pack. It is one the fires all six cylinders. That being the case, isn’t also one (or 1/3) that fires a “waste spark” to another cylinder at the same time it is firing #1? If so, shouldn’t I have a P030X code for that other cylinder when it’s supposed to fire, or is that more of a GM trick? All it shows is P0301 on my code scanner. Do I need a coil pack?

Yes.

The engine has a wasted spark ignition system, which means the coil pack fires two plugs at the same time.

What you might try is move #1 fuel injector to another cylinder, and see if the miss moves with the injector.

Tester

As for those companion cylinders . . .

There is no reason that a bad coil and/or coil pack would affect both of the cylinders it feeds

I’ve seen plenty of waste spark coil packs, where only 1/2 of it failed

Qouting @Tester

"The engine has a wasted spark ignition system, which means the coil pack fires two plugs at the same time."

So, if the coil pack were bad, it should miss on both #1, and its opposite, #5 right? It’s not missing on #5, so I need to swap the injector.

Not necessarily.

There could be a broken connection from the coil to #1 tower inside coil pack.

If you don’t have any spark at #1 cylinder, the problem is most likely with the coil pack.

Tester

“So, if the coil pack were bad, it should miss on both #1, and its opposite, #5, right?”

No, not necessarily

“so I need to swap the injector.”

If you have no spark on one specific cylinder, you should try another coil pack, in my opinion

Let me give you a waste spark story

Inline 6 cylinder, firing order 1-5-3-6-2-4

#1 and #6 are fed by the same coil, yet only #1 is misfiring

I’ve seen it plenty of times

I see.

I have an '01 Mustang which appears to have the same coil pack. I’ll try that first, before spending any money.

Thanks.

Unclip the plug wire from the coil, and just lay the wire on top of the coil tower. Start the car. Grab the wire a few inches from the end and pull it up slowly and see if/how far the coil will throw a spark. Chances are there is no or weak spark.

Not unusual for a Ford coil pack to lose one cylinder.

I used a spark tester that clips to any ground with the spark plug wire attached. The gap can be varied, but there was no spark even at a narrow gap.

Any chance the compression could be low in that cylinder? That can cause a spark plug to fail to fire.
There’s always the possibility of a bad plug right out of the box. I’m leaning towards this not being the case but it has been known to happen; much to my chagrin and more than once.

I’m sorry, I should have posted back weeks ago. A new coil pack was the answer. It’s now running on all six, and the MIL is no longer coming on.

Thanks for all your help.

Thanks for posting the answer!