I have a 2004 Hyundai Santa Fe 3.5L V6. When I was driving a couple of days ago the check engine light flashed and after a while it stayed on.

The codes are P0300 which is a random misfire as well as a misfire in cylinder 2, 4 and 6.

I replaced all 6 spark plugs and the 3 spark plug wires still the same issue.

the car hesitates when accelerating. When I accelerate it looks like it wants to stop, the RPM's goes to almost zero and then it moves and so on. The RPM goes up and down like crazy.

Sometimes it won't move past 1000 rpm I'm moving 60mph and still on 1000rpm and sometimes it works just fine like there is no issue at all.

When idling, the car is fine and everything seems normal it stays at around 900 RPM's.

The car has 158K miles on it.

I uploaded a video to show you what's happening to the tachometer when I accelerate the RPM's jump up and down

Update when i scanned for codes again it seems like other cylinders are sometimes misfiring as well 1, 3 and 5.

I changed all 3 ignition coils still the same issue

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    Great question! Welcome to the site. I edited your question a bit to clear it up. Please validate and read it to make sure I didn't change what you were trying to say. Good luck! Commented Sep 2, 2016 at 4:45
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    Can you log the engine RPM PID vs what the tachometer is showing? Also I'd check the Crank Position Sensor connector. Misfiring on one bank would indicate a variable valve timing problem (the oil control valve is stuck open or there's a short to ground on the control wire) or a cam/crank timing issue.
    – Ben
    Commented Sep 3, 2016 at 20:46
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    @Ben i checked the RPM reading from the OBD Scanner they seem fine unlike the tachometer ! but if it's just a sensor would it cause hesitation ? Commented Sep 10, 2016 at 4:43

1 Answer 1


The tach jumping around is likely a failing ignition failure (or misfire) sensor (IFS or IMS). It is located on top of the thermostat housing on the drivers side of the engine. The part is ~80 USD. It has two bolts holding it on and IFS molded into it.

  • I bought the IFS sensor from amazon for $14 and it fixed the problem thank you, someone on Hyundai Forums also told me to do the same. Commented Sep 16, 2016 at 0:39

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