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so my girls 05 sx 2.0 keeps running p 0304 so i swapped out new plugs, wires and a new coil and i'm still getting it like what more do i need to do? the only thing else i can think of is that the sensor is sensitive and that it goes off when she hits about 5k rpm, if thats so will we juss have to live with it on and is it safe?

How bad is it misfiring?

Have you tried swapping injectors? (Either swapping to a different set of injectors or swapping injectors around to different cylinders, seeing if the misfire follows a certain injector.

It could also be a mechanical reason.

This caused a misfire code in an '05 I just did work on. (A severe misfire.)

ok i'll look into that and probably spray a can of mopar combustion cleaner through it.

The code never appears until on the highway when she hits about 5 k rpm

when i called my buddy at a local shop he told me to try running premium gas through it and adding sum fuel additives

Check to see if the timing belt has slipped a couple notches. This can happen when you wind the engine up that high. It could be that the timing is off since she hits 5000 rpms! That would cause it to misfire.

excon........you didnt think that one through very well did you.....

if the timing slipped a couple spots, well frankly, the motor would be toast.....

if the timing belt jumps, it will stay that way, or jump even further, it wont jump back, so you can rule out the timing all together...

swap the injectors around...if the misfire follows, you have a bad injector, if it doesn't, take it to a shop or dodge to get it looked at...

also, you can rule out the plug wires and coilpack pretty easily in our cars since our cars use a Wasted Spark system...... 2 cylinders fire at the same time.

To test these parts, swap wires for 4 and 1, if the problem switches to 1, its the wire, if it stays at 4 them unbolt the coilpack, and plug cyl 1 into where 4 should to, and plug 4 into where 1 should go. if the problem switches to 1, its the coilpack, if it stays at 4, then its neither the wires nor the coilpack.....almost certainly the injector...

if BOTH 1 and 4 misfire, then you need to have the PCM and coil plug wiring checked out as it could possibly be a bad driver(the thing that switches on/off to signal firing the coilpack), which means the PCM is bad.

first things first though, get the injectors swapped to see what happens.........

^^^^^ Very nice detailed explanation/ trouble shooting guide.
But also if the cam timing being off was the problem the misfire code would be P0300 for multiple/all cyl's.

Why is she hitting 5k?

Adionik wrote:Why is she hitting 5k?

The same reason we do. Gender has not had any effects on the stupid pedal that I know of. My sister runs her husband's pulling truck harder than he does. Ever hear a BBChevy @7800+ rpm? My brother-in-law just goes and shakes his head.
Don't ever compete against a woman with a level head. She will pwn you.

hey i just thought that if she was getting a misfire code it could be from reving the engine too high. My Sister's neon did that yesterday. I figured the timing belt jumped a notch or two because it just cut off on her after she got off the highway and was idling. It probably slipped 2 or 3 degrees. She said it was running pretty rough.

w0158981 didn't say that his woman's car WASN'T misfiring. He just said there was a code.

if reving to high tripped a misfire code, i think many many many people on this site would have that problem



high reving BBC = sweet music

racer12306 wrote:high reving BBC = sweet music

I figured you would like that.

Edit:

excon wrote:hey i just thought that if she was getting a misfire code it could be from reving the engine too high.
He just said there was a code.

w0158981 wrote:so my girls 05 sx 2.0 keeps running p 0304

Misfire for #4 only. The Misfire code 0300 is generally limited to the UDP on '02 pcm's, from exceeding 4000 ish rpm's, If that's what you were thinking of. Just missing on #4, points more to something specific to that cylinder. It could be a weak spring which would be rpm related.

It's all good.

I would check lots of top end stuff. I'd probably look at the plugs first. If they all look the same, then it's probably not fuel related. But look right after the problem occurs. (i.e. when it's happening, shut off the car and coast to a stop in neutral.)

Keep in mind that winter fuel has different additives to keep the fuel from "gel-ing" up, which lowers btus. Lower btus cause more volume of fuel, which makes a spark plug more likely to "blow out". What's your gap? Have you done a compression check? Have you popped off the exhaust manifold to look for excessive soot in the runner for the misfiring cylinder that might indicate either a rich condition or burning oil? Does the car burn more than a quart of oil per 1k miles? Does it burn antifreeze?

Sorry to throw a ton of tinkering work at you, but you really don't have enough information to diagnose the problem yet.

You know, I've never really though about which sensor is deciding which cylinder has a misfire. I would say the knock sensor, but it's sitting right in front of #2, so unless it's hearing it based on comparing it to CKPS and CPS, that's not it. Actually, it's beginning to sound feasible. If you unbolt the knock sensor and reset the ECU (But leave it plugged in) does the problem remain?

esteinmaier wrote: You know, I've never really though about which sensor is deciding which cylinder has a misfire. I would say the knock sensor, but it's sitting right in front of #2, so unless it's hearing it based on comparing it to CKPS and CPS, that's not it. Actually, it's beginning to sound feasible. If you unbolt the knock sensor and reset the ECU (But leave it plugged in) does the problem remain?

I don't think they rely on the knock sensor 100%. The way it was described to me was variations in torque. How it senses that IDK. It may compare the pulse speeds from the crank sensor while it completes the revolution cycle. I can see the knock sensor argument too, as the following cyl has a higher load due to the misfiring one not having output. It may use info from the tach output, crank, and knock sensors to determine the cyl that is the cause of the torque/rpm variance(s).

ok so i finally got to take it out myself now i'm not a car guru but i didn't really notice a whole lot, one thing i did notice though is when i'm stopped at a light the car shakes like crazy, like it matches the engine. Also the cel begins to flash on the dash.

We checked all the plugs, putting in new ones again since she got it, the wires all work, and the coil works fine so, i'm guess its an injector?

i still haven't run an mopar cumbustion chamber cleaner through it but i will.

sorry i can't tell ya mopre but other than that the car works great

occasional demons wrote:

esteinmaier wrote: You know, I've never really though about which sensor is deciding which cylinder has a misfire. I would say the knock sensor, but it's sitting right in front of #2, so unless it's hearing it based on comparing it to CKPS and CPS, that's not it. Actually, it's beginning to sound feasible. If you unbolt the knock sensor and reset the ECU (But leave it plugged in) does the problem remain?

I don't think they rely on the knock sensor 100%. The way it was described to me was variations in torque. How it senses that IDK. It may compare the pulse speeds from the crank sensor while it completes the revolution cycle. I can see the knock sensor argument too, as the following cyl has a higher load due to the misfiring one not having output. It may use info from the tach output, crank, and knock sensors to determine the cyl that is the cause of the torque/rpm variance(s).

On Toyotas the specific cylinder is determined by the CPS detecting a lack of acceleration on that cylinder's power stroke. I would guess that's probably the way it's done universally.

occasional demons wrote: It may compare the pulse speeds from the crank sensor while it completes the revolution cycle.

So my thought process may actually have some merit.

Sure sounds like it!