darkhonda2k2

iTrader: (1)

don’t flame me but this is not on my civic but my gf's 350z, but I am a member here not there and in my exp people here know a lot about a lot also its 4am and vie been at work for 9hours so this might be a little scatter brained

So 350z, 88k miles. After a couple days idle the car experienced the first event of random misfires (it was idling way off, shaking the car and after a few minutes finally threw the P0300 code)

So I fired up the torque app and began to watch the O2 voltages of bank 1 and 2 hoping to see a drastic difference, and also monitored the fuel trim to see that fuel seemed balanced.. Basically just hoping for more direction than "p0300 random misfire"

I tore through the 350z forums and while many posts were started on this topic none had solutions only possibilities (spark, coil, injectors,..., profit?)

So I started small, spark plugs. A couple seemed more fouled up than others but none 100% screaming "look at me!" also while each coil was removed I checked the resistance between the 3 terminals per some poorly described way to check for a bad coil-pack: though none measured as an outlier but one had possible melted bubble so I put this one in the easiest place to reach if need to replace later.

So I reassembled with new plugs, and it seemed the issue was gone... for a whole 1.5 weeks. Then yesterday it happened again, shaking and poor idle randomly, so I pulled the plug connecting to the suspect coil to see if no change would be observed, but there was.. So that coil is not at fault.

Then like magic and with an actual noticeable 'click' the issue was gone and she purred like a kitten the rest of the day.

So now the question to the great minds here.. WTF? Does anyone know other tests to put coil packs through? Has anyone experienced this random misfire?

Any experience or tips are greatly appreciated just to help narrow it down. I would have stethoscoped it but since the issue is random I have not been able to reproduce it in the garage.

Thanks for reading all of this.

ezone

My second choice, after some touchy-feely time with the car so I could experience the same things you did, would probably be to connect a real scanner and gather data from that.
I have only a vague idea of what the car is equipped with in the engine compartment.

Only ran rough and crappy at an idle?
Does it have an EGR valve? My first thought is the EGR was stuck open. (That would not necessarily mean the valve is bad though.) What operates the EGR valve, electric or vacuum?

darkhonda2k2

iTrader: (1)

unfortunately i dont own my own real scanner, just the bluetoothe ODBII reader and torque. and the quick read at advanced didnt offer any new intel

No when it is misfiring it runs terrible at all RPMs, all gears. when it "clicked" (a truely audible event via the exhaust note), the power just came up out of no where and everything smoothed out like it was brand new.

I will check into the EGR valve, I like you dont know what it has so ill have to search their forums again.

thanks for the response.

ezone

EGR stuck open would have the greatest effect at idle, and its effects would lessen with increased RPM/load/throttle opening.

You wouldn't notice it at say, highway speeds and loads.

Stab again.


It's not that I don't know anything about the car, it's that I don't have access to Alldata at home anymore.

darkhonda2k2

iTrader: (1)

Oh well it def exists at highway speeds, in fact the shifter would shake so violently it looks like it would come out of gear. it does seem to happen with cold starts, but does not always go away when the engine reaches temp..

i dont suppose you know what values would be normal for O2 voltages and fuel trim levels.. i started looking at those numbers thinking they would show me if fuel is going in evenly bank to bank, and if the O2 were reporting equal burn.. does that make sense?

it is also burning through gas.. like ~10mpg instead of 25+.. but I assume that is a common symptom of misfire and not very helpful.

ezone

The beauty of OBDII is some sort of standardization across all manufacturers in generic mode.

Ideal O2s and STFT/LTFT will look almost exactly the same as every other OBDII car on the road on your generic data.





I had a better reply all typed out at work, but that laptop ate it in a WIFI SNAFU.

darkhonda2k2

iTrader: (1)

haha isnt that always how it happens. I am going to run the scanner on my civic tomorrow just to get a baseline / idea of what a normal output is

also I looked into the EGR valve on the 350z forums, i think that is going to be my next part to check.

ezone

If you mess with EGR, just disable it (while it runs good), then see if it acts up again.


If it has O2 sensors (not A/F-Rs etc.), the fronts should fluctuate all over the place while it is in "closed loop". 0.00v is lean or fuel shutoff, and close to 1.00v is rich. LTFT should be within 10% of 0. STFT will fluctuate with O2s.

Air/Fuel Ratio sensors, Lean Air Fuel sensors, and the like are tougher to read on a screen than regular O2 sensors.

If it is running bad, O2s and trims are likely to only reflect the running conditions you already see--- symptoms, not the cause.
Generic data really sucks for diagnostics. Factory and high end scanners supply tons of data that can be far more useful.
Generic data is also S-L-O-W to update. Maybe several seconds late.

darkhonda2k2

iTrader: (1)

How would i go about disabling it? is it as easy as just unpluging something?

Thanks for those numbers! It feels good to have an actual idea of what I should see... and did see btw on my civic tonight, my O2 was avg at .5, and my F/T was about 3.5-6.0 on sensor 1.

I started looking at these readings not expecting to figure out what exactly is wrong, but rather hope i could narrow it down (at the very least hoped for a bank 1/bank2 difference to reduce it to 3 cylinders) but also hoping discover symptoms i can bring here

any ideas of where i might find someone with a high end scanner to use that wont cost me a fortune? i'd like to do this work myself for fun / my gf only works 1.3miles away so she doesnt really need her car. lol

ezone

Yes.

Ask around.
The dealer is supposed to be the place...Too bad most people treat it like their last resort (both customers AND management)... Insist on a top gun to fix it, not a rookie or a oil changing lubie.


I know, I know..... Most shops won't employ a full staff of top-shelf talent.



If you think it's expensive to hire a professional.....just wait until you hire an amateur.



Good luck.

darkhonda2k2

iTrader: (1)

i will try that then. verifying it as the root could be tricky with this problem being so sparatic, it went almost 2 weeks without an issue after i changed the spark plugs out..

Zivic

All of a sudden, my 2003 civic gave me somewhat intermittently more p0303, p0301, p0300 and occasionally p0302 and p0304, p0420.

Took it to a Honda specialized repair shop at a Saturday and got turned away after they erase the codes and could not reproduced them after a short drive. I was told that Saturday is usually not a good day to fix cars. After I brought in the car to the same place again, they adjusted engine valve clearance and the problem is fixed. The car is running well and I become realized that it was a little sluggish.

Wonder this may help someone in the similar situation.

darkhonda2k2

iTrader: (1)

zombie thread awakens.. The issue has returned

since my Civic's alternator decided to die yesterday, I took my gf's 350Z to work tonight..

after about 30min of driving i felt a rather noticable 'clunk' and the CEL began to flash..(makes me think im looking for some sort of valve but thats just my uneducated guess)
it wasnt shaking as violently as it had before but I have to assume its the same misfire issue (will check for codes when I get home)
this continued for <5min, then a second 'clunk' and all was right with the world again.. until it happened 3 more times over the next 30min.

the last two times seemed to be when going up a slight hill [keeping throttle as constant as i can w/o cruise control] though im not sure if that was conicidence or what but ill keep a more close eye on that when i drive home..

thinking caps on everybody... ideas??

ezone

What year is the Z?
Is the only code a P0300 again, or something different this time?

darkhonda2k2

iTrader: (1)

The Z is an 03, ~90k
When I drove home in the morning the car was running well, untill about 10miles from home when the CEL came on (not flashing like before).

got home, turned the car off, got my scanner from inside, started the car again, no CEL, pulled stored codes and came up with a P0301 (Cyl 1 misfire). This is different, but no time to look into it this morning as she needed her car for work.

ran torque app the entire way into work tonight, watching for O2, and F/T readings that seemed off but of course no CEL or issues the entire drive in tonight. will run again on my way home.

ezone

Sounds like a different situation this time, you didn't say it went CLICK and ran real crappy like the last time.



I don't see that it has an EGR valve, I don't see any bulletins on Alldata, I don't see anything helpful yet.

What is the freeze frame data? Idle, or flying down the road?
What does the plug look like, and
Swap the #1 coil with another cylinder and see if the miss moves or stays on #1.
Then see what happens. Apply a bunch of logic to whatever the answer is.


How many aftermarket ignition coils are on it already? What cylinders are they on?

Shake wire harnesses with it running, see if it stumbles in any way.....?

All I can really do is start with the basics that would apply to any car/engine.
I have no intimate knowledge of Nissans at all.....In fact, I never really cared for their engineering at all.


Have you checked if recalls are up to date? Check with your dealer.

darkhonda2k2

iTrader: (1)

My gf says she felt a 'click' before but I never did, it did however shake violently before which it is not donig now.. so i too feel it might be a new issue.

I found people talking about deleting the egr and such on the 350z forums so it must be there somewhere, but as ive never seen/dealt with one I have no idea what to even look for.

Freeze frame rate?? All O2 readings and F/T readings I was looking at was highway cruise speeds (same condition as the 'Click' occured two days ago)
After I read the P0301 code, I cleared it just to see if it would come back right away, or what conditions would make it come back.. so far 100miles and no P0301 or any codes are present.


ZERO aftermarket coils are on the car. this car is 99.6% as it came from the factory. I replaced the spark plugs when the initial problem started, also inspected and resistance tested teh coil packs per description found on my350Z.com

ezone

"Freeze Frame" is a collection of engine data saved at the time the code was set in memory. Coolant temp, MPH, fuel trims, and some other parameters are included, and some manufacturers store a lot more data than others.
This is done so you can know exactly what the conditions were at the time of the failure, like the car was in the middle of warmup at 143 degrees, the throttle was open 9%, the car was going 37MPH, bla bla bla....

So then you don't have to wonder:

You can drive it in the exact same conditions by using that data.

Freeze fame data is included with all OBD2 emission related codes.

Make sense now?


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On the EGR, Alldata didn't list it in the powertrain controls so I think it shouldn't have one. The function or effect that an EGR system would perform is now accomplished through the variable camshaft timing.



Still no more guesses about the problem here though.
HTH

darkhonda2k2

iTrader: (1)

That sounds like the key ive been looking for! now.. how can i pull this magical data out of the ECU? a dealership? i dont remember seeing that capability listed within the torque app.

ezone

It isn't magical at all.
All OBD2 computers do it.
Some manufacturers were even doing it long before it became mandated.
No dealer needed to get the basic set of data.
I would hope that most code readers can get it.
You just need to find it.
I don't normally use code readers though, so I don't know that all cheap readers can get it. I would imagine that the cheapest of the cheap can't do it.
(This is an area where you really do get what you pay for.)

The code MUST be present though. You erased the code, so all stored data that came with the code is gone too.

Wait for it to happen again, then try.
OTOH if it happened while you were driving, you should have a good idea of what you were doing when the CEL came on. Right?



Side note: The data that a high end scanner or a dealer scanner can retrieve could be much more than what a generic scanner can retrieve.
Like I said before, some manufacturers give far more data than others. Some manufacturers only gave the bare minimum no matter what.
I have no idea what data any Nissan product would possibly have available beyond the parameters mandated by OBD2.
I have never used a Nissan Consult scanner.


HTH

darkhonda2k2

iTrader: (1)

right on. I did clear the code because I wanted to replicate the issue. im a scientist at heart.. all tests must have multiple sample sets.

plus I figured the code was a P0301 so as long as i know what it was i can still look for issues in cyl1 until the code comes up again.