2019 Hyundai Veloster P0300, P0301, P0302, P0303, P0304

Maintenance/Repairs
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1

Hey all,

My 2019 turbo veloster threw a misfire code on all cylinders. The vehicle seems to start and idle just fine. I don’t think it has anything to do with the ignition system or head gasket issue since all cylinders threw a misfire. Where should I look first? I could also smell some fuel on start up, haven’t found any leaks though.

Here’s the OBD snapshot that the car took
Fuelsys1: CL
Load_PCT(%): 38.4
ETC(F): 185
SHRTFT1(%): 7.0
LONGFT1(%): -0.8
MAP(inHG): 26.6
RPM: 2276
VSS(MPH): 24
SPARKADV: 10
IAT(F): 135
TP(%): 28.6
Run Time: 64 sec
FRP(PSI): 932.6
EVAP_PCT(%): 0.0
FLI(%): 94.9
BARO(inHg): 29.8
VPWR: 14.294
LOAD_ABS(%): 77.8
EQ_RAT: 0.999
TP_R(%): 19.2
AAT(F): 97
TP_B(%): 28.2
APP_D(%): 29.0
APP_E(%): 14.5
TAC_PCT(%): 24.7

Thanks all!

2

If you are the original buyer, the car may still under warranty. Take it to a Hyundai dealer.

3

Is car stock? Stock tune?

4

All stock with the exception of a borla catback exhaust.

5

Is it really that hot there?

Tester

6

Definitely! Southern Louisiana, 95F-100F during the day. The code went off after a minute of driving, so easily that temp in the engine compartment.

7

How many miles on the car. Believe it or not these call for spark plug change at 45K miles.

8

Good to know, mine is overdue then. I’m at 55k. But I wouldn’t expect that to trip a misfire code on every cylinder all at the same time

9

https://www.hyundaivelostermanuals.org/veloster-261-normal_maintenance_schedule.html

Tester

1 Like
10

The only thing slightly unusual I notice on the diagnostic snapshot is the intake air temperature, and the 7% short term fuel trim. Since thelong term looks ok, not sure if the short term is indicating a problem or not. So what to do about themisfires?

Common sense says the first step is to bring all the routine maintenance tasks up to date. As the spark plugs are due for replacement , do that, and replace the engine air filter at the same time. Unless you have reason to believe there’s been contaminated fuel in the system, the fuel filter should be ok as is. If you think the fuel might be contaminated, take a sample to look for signs of layering, or better method is to ask your shop to check for you. Hopefully just new spark plugs and air filter will solve the misfires. If not, I suspect you have some sort of problem with the air/fuel mixture, either on the air or fuel side of the equation. Since the computer is saying it needs to add more fuel than expected based on the measured air flow into the engine, that suggests the possibility there’s some sort of air leak. Either on the intake side or the exhaust side. The 932 PSI fuel rail pressure , if I’m interpreting that correctly, suggests this is a direct injection engine. Maybe the air leak is associated w/some part of the fuel system, since you are noticing a fuel odor too. Inspect those parts.