P0305 Code (misfire code) Topic is solved

[abscate]

Song...I would get that injector wiring sorted out, that could certainly trip up the injector timing which is sure to misfire.

You can leave that cover off too, those wires sure are pretty

[songzunhuang]

Song...I would get that injector wiring sorted out, that could certainly trip up the injector timing which is sure to misfire.

You can leave that cover off too, those wires sure are pretty

Thanks for your input. I think I will leave the cover off and see if that works. If it does, I can cut, re-solder and then use heat shrink tubing to protect the wires. I did wrap it with electrical tape in hopes that it would remedy this.

I should mention that I checked the plug and it has a healthy looking "ash" on the platinum plug. There's no sign of any moisture (unburned fuel). The plugs only have about 20K miles on them and my understanding was that platinum plugs last a lot longer than that.

[abscate]

Plats should give you a good 50k

If the Fuel injector isn't firing, you won't have any fuel on that plug though.

[songzunhuang]

Well, it's all the same still. The wire is not the problem. I took off the cover and ran it until the code came back. It only took a few minutes. If I reset the code using an ODBII reader, I can drive the car on the freeway for a long time without the code. It's only when I am at low speeds, like idling under 1000 rpm that the code comes back.

Does anyone have any ideas?
Could it be the injector? If so how do I test it? Again, when I check the plug, it's dry and it looks "ashy" just like the other plugs I have checked. Scratching my head a bit.

[abscate]

You can send your injectors out for cleaning and testing fir under $100 for all 5... But first, get some new,seals, and swap,injector 5 and 4 and see if the code moves with the injector.

You can swap them using the old seals too if you are careful but watch for crumbly seals

The cylinder assignment for misfire isn't always perfect btw

[erikv11]

Like the spark plug, injector and injector wiring can be tested by swapping them around. One at a time of course! Easiest to start with the wiring (the injectors all fire at the same time so it doesn't matter which order you plug them in), then the injector itself is a bit more of a hassle (watch out for falling seals and be careful to not damage the o-rings).

About the cap, I don't know that a visual is good enough test. And I suspect you don't want to hear this but until they are tested, I would also consider those pretty new wires could be the problem. From your first post it sounds like the misfire showed up soon after installing the new wires? The only wires out there with rock solid reputation are Kingsborne and Bougicord, the dogma is that "any other brand may give misfires." Do you still have the old #5 wire? Can you grab a cap from a junkyard, for testing purposes?

[songzunhuang]

You can send your injectors out for cleaning and testing fir under $100 for all 5... But first, get some new,seals, and swap,injector 5 and 4 and see if the code moves with the injector.

You can swap them using the old seals too if you are careful but watch for crumbly seals

The cylinder assignment for misfire isn't always perfect btw

Thank you. This sounds like a good next step. I had changed the seals on the injectors when I did my PVC service a few months back, so I hope that it isn't the issue. I see no sign of leaking seals around any of the injectors. It looks like I can get a re-built injector for under $40 if it is the issue.

I'll put this on the to-do list for this weekend.

[songzunhuang]

Like the spark plug, injector and injector wiring can be tested by swapping them around. One at a time of course! Easiest to start with the wiring (the injectors all fire at the same time so it doesn't matter which order you plug them in), then the injector itself is a bit more of a hassle (watch out for falling seals and be careful to not damage the o-rings).

About the cap, I don't know that a visual is good enough test. And I suspect you don't want to hear this but until they are tested, I would also consider those pretty new wires could be the problem. From your first post it sounds like the misfire showed up soon after installing the new wires? The only wires out there with rock solid reputation are Kingsborne and Bougicord, the dogma is that "any other brand may give misfires." Do you still have the old #5 wire? Can you grab a cap from a junkyard, for testing purposes?

I wasn't aware that the injectors all fire at the same time! That seems a bit contrary to the marketing copy of the engine computer firing the injectors at exactly the right time.

Last time I looked, it didn't look like I had enough slack in the #5 injector wire to easily move it to another cylinder. Perhaps there's more wire inside the protective jacket?

RE: The timing of the misfire. It was there before I changed the plug wires. I was hoping that the wire was the cause of the misfire since I do not ever recall changing the wires in the 239K miles I have had the car. Alas, it wasn't the issue. Also, I chunked the old #5 wire.

The cap is an interesting one. When I inspected it, it looked super clean. There's no sign of any issues at all. All contacts are clean, no arcing (black marks or trails. Center electrode looks intact and clean) and the same goes for the rotor. It seems that a misfire isolated to one cylinder would be hard to pin on a rotor since it services all the cylinders. I can see the cap being a possible issue. It has been replaced in the past, but I forget how long ago. I may swap it as a preventative measure, but it does feel a bit like throwing parts at the problem without a more positive way to test.

[polskamafia mjl]

...the injectors all fire at the same time so it doesn't matter which order you plug them in...

Wait, what? That doesn't sound quite right.

EDIT: Apparently it is a thing. Its called batch fuel injection. Interesting concept and super counter intuitive to me. Today I learned.

[erikv11]

... I wasn't aware that the injectors all fire at the same time! That seems a bit contrary to the marketing copy of the engine computer firing the injectors at exactly the right time. ...

Haha, nice. Ah yes, the dichotomy of marketing and the real world. It's like Newton's fifth law.

I don't know if the #5 wire is long enough to stretch to others, just a basic troubleshooting suggestion. Agreed, maybe if you open up the jacketing on the harness. I would check it out, you can get replacement plastic loom for pretty cheap from the auto parts store.

Don't throw parts at it, I'm not suggesting that! Well, unless you have them. I have 'em, so I use 'em. Next tune up, save the old cap ... It's just that with ignition problems, it is usually an ignition component, if you run out of options then it would be good to be able to troubleshoot (not just replace!) the cap.

I think with ME7 the ECU switched over to sequential injection. Motronic 4.3 and 4.4 are strictly batch injected.