I've never had P0300 come up on any of my vehicles but hopefully this will send you in new directions. Nissan Versa P0300: Engine Misfire Detected | Drivetrain Resource I know some models of the Versa had fuel regulator issues. If that's not the problem I'd try testing the cam/crank sensors and check the EGR system is operating properly. I would think that a cam/crank sensor and probably EGR problems would set other codes as well.

 

Thanks, I'll check out the fuel regulator and EGR system.

 

My first guess would have been a vacuum leak but if that were the case I'd think you'd also have other lean codes.

 

Have you tried changing out ignition coils? What shape were your plugs when they were replaced? If they had carbon build up, I would start with the coils. Just my .02

Edit: Additionally, what brand spark plugs did you purchase? Did you go oem or aftermarket?

 

Well, I replaced the fuel pump, which has the regulator pump and filter in one unit. I thought it was fixed, ran great for about 30 miles, then started missing again. I'll have to check out the EGR system. Hopefully that is the problem.

 

Oh, i replaced the plugs with NGK Iridium plugs.

 

I think at this point I'd try to find out how to run a diagnostic on the cam/crank sensors. Often if the crank sensor is bad the engine won't start and run but that's often not the case with the cam sensor.

 

I think that may be my next move. I have already replaced the crank sensor, and that’s the hard one. I have tried to find info on the EGR, but it seems these don’t have one. Maybe the PCV system?

 

7 Symptoms of a Bad Camshaft Position Sensor (and Replacement Cost in 2025)

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I had to replace the cam sensor on my '02 Ford Escort this summer. I had code P0340 which is a cam position code. There were several drivability issues poor fuel mileage, rough idle and often stalling when stopping at a stop sign/light or when hitting the gas to take off from a stop. After replacing CPS all the drivability issues were gone.

 

Well, replaced the cam sensor and all the coils just in case. Took it for a drive and thought it might actually be fixed, ran great! then about five miles later I got a check engine light with a P0300 and P0302. Then about a mile later it died and wouldn’t restart. Im about to give up.

 

Dang, I'm running out of suggestions. I'd go back and check the wiring harness going to #2 to be sure there's not problem there since that's the specific cylinder code it spit out. Might also want to move that coil to another cylinder to be sure the misfire doesn't move. If it does you got a bad coil. If I come up with any other ideas I'll post them. I know you said compression was good but was there any cylinder that was low enough that it might be caused by a bad head gasket and could possibly be the cause of the misfire? Or two side by side cylinders where the compression was lower and the gasket could be bad between those two?

 

I am very sorry that your Versa gives you so much trouble, where you spent a lot of time and replaced a bunch of parts. Not to mention a lot of frustration.

Now, looking back, do you think it would be less trouble to bring your car in the first place to the reliable shop, where they do a proper diagnostic before they change parts, and attempt to fix it right the first time? Do you think even with their fees it still would be less expensive than the amount you already spent?

 

As it sits right now, definitely not, it seems the reliable shop is throwing much more expensive parts at it with no fix yet. I think I’m $3200 in at the dealer and I’m not any closer to finding the problem.

 

Typically people don’t work on their own cars to save the trouble. I might think about taking it in if I knew of a reputable shop. Heck, I had a coolant leak on my truck that I took in recently. I figured the dealer should know what they are doing. But they literally threw parts at it trying to find the problem. It was in and out of the shop for over a month. Total bill for what ended up being an oil cooler was over $3500. They ended up replacing the hoses, water pump, 3 way coolant valve, and egr cooler before finding out the coolant was leaking into the crankcase.
But I enjoy working on them. And under normal circumstances, I can narrow a problem down to a few things. If I can replace them both for the cost of a shop replacing one, then I’m ahead. I also received the knowledge from the experience.

 

Thanks for the suggestions, I appreciate it. I’m going to yank the intake off today and replace the new coil with the old one and double check the wiring. Compression was 172-165-168-175.

 

Doesn't look like the compression numbers vary enough that it should be having any impact. Bad head gasket was just a thought.

 

When you find the problem please post what the problem was so if anyone else runs into this problem they'll have an idea what to look for. Here's a thread where someone else was having a similar problem but they didn't post the solution to the problem. P302 Cylinder 2 Misfire, What Else Could it Be?

 

Will do, definitely!

 

Well, had it towed to to the local shop, they couldn’t figure it out but they thought it was the computer. Charged me $150 and said it would need to go to the dealer because they can’t program the computer. Had it towed an hour to the nearest dealer. They said the Nissan’s do not like any aftermarket coils. I told them to go ahead if they thought it would fix it. Sure enough $1500 later and it’s running great again.
I would have never thought it would burn up aftermarket coils and pop the coil fuse within 20 miles.

 

Well, had it towed to to the local shop, they couldn’t figure it out but they thought it was the computer. Charged me $150 and said it would need to go to the dealer because they can’t program the computer. Had it towed an hour to the nearest dealer. They said the Nissan’s do not like any aftermarket coils. I told them to go ahead if they thought it would fix it. Sure enough $1500 later and it’s running great again.
I would have never thought it would burn up aftermarket coils and pop the coil fuse within 20 miles.

Anymore, especially with imports, if you buy the cheaper parts, you're doomed. I just recently watched a vid from Scanner Danner where they went through 4 new identical aftermarket ICMs, each failing from onset. The question posed was "who is going to pay for all this lost time" because the mechanics shouldn't have to eat it, and the customer shouldn't either. Doesn't matter that the part is warranted and refundable. Untold hours of diagnostic labor are wasted due to inferior/defective products. Mechanics have little choice other than insisting OEM parts are used.

 

Well long needed update. So about 4 months after the coils, it starts missing again, back to the shop it goes, figured one of the coils went bad again, $2000 dollars later they said the MAF sensor needed replaced and the 4 month old spark plugs. Ran ok for about 2 weeks then started missing again. I heard a funny rattle in the exhaust so I yanked it off. Looks like the misfires took out my cat and shot the particles into the muffler. I was hoping the particles plugged the exhaust a bit to cause the miss so I Hollowed out the cat to test out my theory and put on a new muffler. Still misses. Back to the dealer it goes…. I hate this car…

 

Sounds like it was just a bad coil. The car doesn't know what kind is on there.

Now cross's your fingers and hope that p0420 doesn't pop up soon from the misfire!

For future readers, these don't have egr valves. The same effect is achieved with variable valve timing.

 

Sounds like it was just a bad coil. The car doesn't know what kind is on there.

Now cross's your fingers and hope that p0420 doesn't pop up soon from the misfire!

For future readers, these don't have egr valves. The same effect is achieved with variable valve timing.

Actually, I still have not found the problem. So far I have replaced, the cam sensors, crank sensors, coils twice, spark plugs twice, intake gaskets twice, MAF sensor, fuel pump, fuel filter, hollowed out the cat (because it had melted from the misfire), the muffler, and had the fuel system professionally cleaned.

It still misfires. I hate this car....

 

There is still quite a bit that can be tested, bit at this point I'd recommend finding a local diagnostic tech to just tell you what it needs.

You really want to ignite everything you e done and follow the data where it leads, but it doesn't sound like you have the equipment to do this accurately, and it takes knowledge/experience to evaluate the data.

There is still injectors and compression that I didn't see mentioned. In theory I believe bad belt tension could cause the computer to think there is a misfire. How did you test for vacuum leaks?

 

Any new updates on this issue? You have taken care of many of the things that could have caused the issue. Intermittent/ re-occurring problems are some of the hardest to track down.Most people don’t have the skill set to solve just the basic stuff, much less this. You should feel good on the operations that you have performed as they are not for the faint of heart and more than just the work of a parts changer as they indicate a level of diagnostics and skill not found in the average person. The only thing that I could suggest at this point would possibly be either an electrical contract (plug) issue or possibly injector(s) issue. Without some live data it’s really difficult to accurately diagnose.

 

Live data IS the key to figuring this out. I'd order a cheap Bluetooth OBD2 dongle on Amazon or your favorite shopping site, and get an app to use it on your phone. I prefer incardrpro over others I've used and the whole rig will only set you back like $15. No need for any expensive ones like bluedrive or that despicable Fixd one.

 

Agreed, live data is the key. Using your stft and ltft data you can probably diagnose most misfire issues. Other data like O2 and MAF data is also helpful. I had a similar issue and replaced the coils and plugs and it went away for about 50 miles, then bam, it came right back. Come to find out that one of the coils failed again. Been driving it around for about three weeks now and no issues! Manufacturing quality is not always what it used to be, regardless of who made the goods. I try to stay away from the dealership as much as possible because they are no better that a lot of the independent garages out there. Although difficult to find a competent shop they are out there.
Even a cheap scan tool that gives live data can be very helpful in diagnosing an issue like this.
I did make sure that I force triggered a “bad MAF sensor code” to clear out my LTFT and it was part of my repair. Of course I reset it and cleared the code to force a re-learn on that parameter.

 

I have the same or similar issue with my 2018 versa. Started with clogged cats( yes cats). There is an exhaust manifold cat and a cat after that.
Never got a cat code so never knew it was the problem until I couldn't go over 50mph.
Punched out both cats and car ran great for 2 months. Misfire came back and mph went down. Changed upstream 02 and mpg is back except for when the car is under a load or accelerating. Started toying with down stream 02 with fouler's and is getting worse. Going to the store to get new down stream 02 and test with and without fouler.
OBD2 says it's rich which I believe is coming from down stream 02 leaning it out.
Stft is running 0 to -?? . I think the random misfire is a fuel issue. It does not feel like a spark or coil issue. Misfire only occurs (flashing check engine light) at idle and stops flashing when driving.
It would be great to fix this POS because I am getting 35mpg + and 45mpg at 62mph drafting and vehicle.

 

What is your LTFT?
If it is normal then I hate to say it but look at your spark plugs.
You can reset the STFT and LTFT by forcing a bad MAF code. Disconnect the MAF plug (carefully) and start the car up and run it for a few seconds. Clear the codes and reconnect the MAF plug and your LTFT should be reset. Not you can get some accurate and current data to work with. That should help with the diagnostics part and hopefully point to the culprit.
Good luck!