Let me start off by saying, I have looked through all related questions regarding this sort of issue... so I'm definitely not wasting anyone's time.
The first time I found this problem I was on a spirited drive and found my 2009 hyundai accent hatch (5spd 140k mi) misfiring above 5k rpm. The only thing I have personally done is, I bored out the beginning of the intake where the air is initially sucked in from behind the grill. (OEM) It looked like some plastic structural support pieces inside an oval opening. Nothing else was touched.
So, I ended up scanning the codes after my check engine light came on flashing. I made sure this wasn't a fluke thing and brought the rpms up to 5k a couple more times when driving... P0337 low input is what came up, along with misfire on cylinder 2 and 3.
After I cleared the codes, I switched the coilpacks around, cylinder 1 to 2 and 3 to 4. Went for another drive, and now only the sensor code (P0337) is coming up. I bought a sensor at autozone hoping to fix the problem to no avail. I still get a low input code and misfire above 5k rpm. I ended up changing plugs and coils, still not fixing the problem.
I just got my car back from the local shop down the road and the mechanic that looked at it is clueless! That may be due to lack of information/miscommunication because my dad told him it was a misfire above 4k rpm, etc... I was told I need to bring the car over when the check engine light is ON. As of right now it isn't on, and it only stayed on for a few days before disappearing. I still have a misfire of course. When this problem first started the CEL would flash (misfire) but it seems it isn't doing that anymore. I have also found that the misfire has nothing to do with the position of the throttle, it only has to do with rpm. As soon as I go above 5.1k to 5.2k it misfires like a M-effer.
I'm not all that knowledgeable about the inner workings of engines and processes of elimination, but the only things I think of it possibly being are; an electrical issue, timing, or the cvvt. I would GREATLY appreciate it if someone can even point me in the right direction. Anything helps.
Thanks,
-Trent.
I was also told by another shop to look into getting an OEM sensor, but the hyundai par websites are very vague and 3 or 4 things come up as a ckp sensor that range from 80 to 200 dollars! So before spending more money I thought I'd try to get more opinions.
I'm happy to see people trying the search before posting. Thank you.
However, it sounds like you missed the Frequently Asked Questions.
There you will find a whole page about diagnosing misfires. So have a look that, try some things, and get back to us with the results.
Also, you didn't post the whole diagnostic trouble fault.
P0337 means: Crankshaft Position Sensor A Circuit Low
(again, FAQ has another section for dealing with check engine lights)
Run through the "Diagnostic and Repair Procedures" on this page: https://www.obd-codes.com/p0337
I'm not sure what you mean by the whole diagnostic trouble fault. But I will read into that article and get back to yall with some updated information soon. Thanks Joe!
you said "low input" was the fault. The rest of it is pretty important.
I don't have easy access to a 10k dollar scan tool so that is all that came up when I used my buddys scanner.
Evidently, you have access to internet, so type P0337 into a web search. No special tools required.
It was explained in the "Frequently Asked Questions" on our main page.
As it turns out, I took the sensor out to clean up the area around the orifice, and to see if there was anything going on with the sensor itself. I bolted it back on and also checked the wires going to and from the sensor. I'm not sure if there was an air gap or what but my misfire is GONE. This really goes to show that any time you have a problem with something you just changed/fixed, to retrace your steps and maybe it is something as simple as not being fully tightened or debris on the mating surface of something that needs to be air tight. Thanks again Joe!
I'm glad you solved your mystery. Happy motoring.
