CARGUYS™ - Rough engine - Misfire on Cyl 6 (1 Viewer)

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Previously incredibly reliable 2010 Hyundai Genesis 4.6L (Multi Port Injection) - 92k Miles

Started last week.
• Tues threw check engine light for "Coolant Temp Sensor". Checked coolant and was low. Added more. Engine never got hot. 
• Wed it's a cool morning. I attempt to drive to work and 1/4mi down road it starts running rough and check engine light blinking. I pull over immediately and have it towed to dealer. 
• Dealer diagnoses as two cylinders missing (4 and 6?). Suggests tune up and replace coolant temp sensor. I agree. 
• Replace Plugs but not wires. Coolant temp sensor on order. Engine still having issues w/. misfire on 6.
• They tell me to run a can of seafoam through a tank of premium and see if it clears an injector on 6 (possible issue?). Said the next stop is to replace an injector on that cylinder. 

Obviously I'm not all that excited about playing the expensive game of "Let's throw parts at this". 

Symptoms:
• Rough idle and uneven under load. 
• Seems to be worst when first starting or cold weather (haven't been able to discern which factor yet) 
• Seems a bit smoother at higher RPMs. 

Any ideas? 
 

 

[SWC]

check oxygen sensors and throttle position sensors so many times that is what is messing up your mix or injection system and not an injector just something to give a whirl to brohan take that to the bank ps i hope that your hyundi has about 10 kc lights so everyone knows you also own a jeep 

 

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check oxygen sensors and throttle position sensors so many times that is what is messing up your mix or injection system and not an injector just something to give a whirl to brohan take that to the bank ps i hope that your hyundi has about 10 kc lights so everyone knows you also own a jeep 

Thanks GB. I'll check into that! 

But, I don't own a jeep :(  
 

 

[playin4beer]

My Hyundai that had similar issues turned out to be a bad VVT Solenoid..  It's solenoid that controls the timing, based on oil pressure.. 

Should be two of them, one for cylinders 1,3,5,7 and one for 2,4,6,8.... 

 

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My Hyundai that had similar issues turned out to be a bad VVT Solenoid..  It's solenoid that controls the timing, based on oil pressure.. 

Should be two of them, one for cylinders 1,3,5,7 and one for 2,4,6,8.... 

Thanks, 

Interesting angle, however wouldn't I likely be seeing issues across the entire bank of cylinders instead of isolated to 6? I could be wrong though. I'll look into it. Thank you. 

 

[Dan Lambskin]

Previously incredibly reliable 2010 Hyundai Genesis 4.6L (Multi Port Injection) - 92k Miles

Started last week.
• Tues threw check engine light for "Coolant Temp Sensor". Checked coolant and was low. Added more. Engine never got hot. 
• Wed it's a cool morning. I attempt to drive to work and 1/4mi down road it starts running rough and check engine light blinking. I pull over immediately and have it towed to dealer. 
• Dealer diagnoses as two cylinders missing (4 and 6?). Suggests tune up and replace coolant temp sensor. I agree. 
• Replace Plugs but not wires. Coolant temp sensor on order. Engine still having issues w/. misfire on 6.
• They tell me to run a can of seafoam through a tank of premium and see if it clears an injector on 6 (possible issue?). Said the next stop is to replace an injector on that cylinder. 

Obviously I'm not all that excited about playing the expensive game of "Let's throw parts at this". 

Symptoms:
• Rough idle and uneven under load. 
• Seems to be worst when first starting or cold weather (haven't been able to discern which factor yet) 
• Seems a bit smoother at higher RPMs. 

Any ideas? 
 

Don't they have like a 10 year / 100K warranty? 

 

[Ron Swanson]

Ah, parts darts.  I hate that game.  Check the cylinder coil or the coil wire connection.  You can swap the coil to a different cylinder and see if the problem follows the coil.

 

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Don't they have like a 10 year / 100K warranty? 

Not when buying used. 

 

[playin4beer]

Thanks, 

Interesting angle, however wouldn't I likely be seeing issues across the entire bank of cylinders instead of isolated to 6? I could be wrong though. I'll look into it. Thank you. 

Yes, but you said it was misfiring on 4 & 6... Usually if this unit is bad, it will come up "random misfire" code..  If it's now just missing on 6, it's probably not the vvt solenoid.. But when mine was doing it, it was misfiring on different cylinders, but not all at the same time, so the code was different each time..

 

[TheWalkmen]

Sounds like the same issues I had. Turned out to be a faulty Johnson rod.