P0305 Code (misfire code) Topic is solved

[songzunhuang]

So my local parts shop had a cap and rotor that was compatible with my car. I went ahead and changed these items in my car as a preventative measure. Well, after doing this work in the dark, I can say that my misfire was definitely not because of the cap and rotor.

i was using an LED light and doing this at night. Odd how it affected all the colors. The new blue wires I had installed really got all whacked out. They almost look fluorescent.

Transferring the wires from old to new cap. This is right before I remove the old cap.

It's time to explore the injector now...

[abscate]

When you swap 4 and 5 take off the connector and put it back on the new injector in the same place. I think you are right that you won't reach without straining.

By the way, the injectors should have 12V on them permanent and. Are fired by grounding with the ECU. Checking 12V supply at each connector , starting with number 5 might be good

[songzunhuang]

When you swap 4 and 5 take off the connector and put it back on the new injector in the same place. I think you are right that you won't reach without straining.

By the way, the injectors should have 12V on them permanent and. Are fired by grounding with the ECU. Checking 12V supply at each connector , starting with number 5 might be good

Allright, I'll give it a try this weekend. While swapping the cap and rotor, I looked at the injector wire again and verified that #5 injector connector won't reach over to the other positions.

I have noticed that after about 1,500 rpm it all smooths out. I've driven the car to the airport 26 miles away and it never tripped the code or ran rough when above 1,500rpm. This leads me to believe that if an injector is involved, perhaps it's clogged just enough that it is an issue at lower rpms? It just doesn't make sense that it runs just fine otherwise.

Question: so if the injector is always energized and grounding by the ECU causes it to spray fuel, is the only variable the length of time of the fuel spray? There doesn't seem to be an "intensity" of the fuel spray that is controllable. It's either on or off right?

Oh to heck with it, I just bought a remanufactured injector. If I'm going to take it apart, I may as well just replace it

Now I'm anxious for the weekend as the mystery is killing me.

[erikv11]

Yes: In the ECU programming (the tune), there is a variable for the injector pulse length. So if you swap in an injector that doesn't match the ECU, or if you swap in an ECU that doesn't match the injector, you can adjust the tune to accommodate (deliver the expected amount of fuel) by changing the pulse length.

[songzunhuang]

So I am getting a bit cornered. I got a new injector and replaced the #5. The car ran worse than before. So about the only thing left was the plugs. I replaced all 5 plugs with NGKs with the new injector. Not so good. I put back in the original injector. The car ran a bit smoother, but after a day of driving, the code came back.

At this point, I will have to check the compression. I am very worried that if low compression reading results, it may be the end of the line for the car. I can't see rebuilding the head or this engine at 249K miles. There's a lot that needs to be done cosmetically and I can't see how it will be a good value.

OK, I won't give up yet. A compression tester is next... stay tuned.

[gswede]

What make are those blue plug wires?

Still got the OEM wires? If so, I`d try with the old wires.

Plugs, what have you gapped them to?

[erikv11]

If I am following correctly you didn't try swapping the original injector, I would do that between 5 and 1.

Just FYI on the injector you might be better off with a junkyard white injector (or even a set), or just sending them all in for flow testing and cleaning (about $20 per injector, I like cruzinperformance.com). They almost always check out good anyway, but at least you get the numbers to settle that issue.

[songzunhuang]

What make are those blue plug wires?

Still got the OEM wires? If so, I`d try with the old wires.

Plugs, what have you gapped them to?

Plug wires are also NGK, just like the new plugs I purchased and installed.

[songzunhuang]

If I am following correctly you didn't try swapping the original injector, I would do that between 5 and 1.

Just FYI on the injector you might be better off with a junkyard white injector (or even a set), or just sending them all in for flow testing and cleaning (about $20 per injector, I like cruzinperformance.com). They almost always check out good anyway, but at least you get the numbers to settle that issue.

I did not swap, but I did replace #5 with a new injector and it ran worse than before so I put the old one back. When I put the new injector in, the CEL was flashing after the misfire. It never did that before. Normally the light comes on and thats it. Also the stutter would only happen at idle speeds. When I put in the new injector, it was stuttering at idle and acceleration. It was way worse.

I guess I cold do a swap like you indicated. At this point, I may as well eliminate that.

Incidentally, why do you think I should swap with #1? Why not one of the other cylinders? Is there a logic here that I am not aware?

[erikv11]

I know, I did read your injector replacement notes, but TBH I wouldn't trust an eBay rebuilt injector unless others have vouched for the seller. I know I sound like a conspiracy theorist on parts makes here, but you do need to be somewhat picky about your parts sources, it has been shown over and over again here on the forums.

On the 1-to5 I was thinking about abscate's earlier comment that sometimes the P030x reports are not always accurate to the correct cylinder. I haven't had that experience but it may be true ... So based on firing order and physical proximity I'm just speculating that #1 is less easily confused with #5 than, say, #4. https://www.matthewsvolvosite.com/forums/vie ... hp?t=18523.