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Engine sputtering and shutting off

Tiny
MELMACK3226
  • MEMBER
  • 2006 HYUNDAI SONATA
  • 6 CYL
  • AUTOMATIC
  • 150,000 MILES
My car started making a knocking sound when letting off the acceleration, slowing down and stopping. About two days after the sound started it began sputtering and cutting off as if it is not getting gas. I have already replaced fuel pump, filter, spark plugs, wires, radiator hose, and breather. Any idea what this is? My check engine light is not on.
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Wednesday, April 18th, 2018 AT 8:54 AM

13 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Still do a scan as many faults do not set a check light, often crank angle sensors on these cars give problems like what you are having.
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Friday, April 20th, 2018 AT 6:15 AM
Tiny
MELMACK3226
  • MEMBER
  • 7 POSTS
It looks as if my oil is milky. Blown head gasket? My car has never ran hot, no white smoke, still starting and idling fine. I also changed the crankshaft sensor. No luck.
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Saturday, April 21st, 2018 AT 7:41 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,476 POSTS
Milky oil is not a good sign. I would pull the plugs and look at them for signs of coolant. How long has it been since an oil change? Does it get driven daily? Asking that because if it sets a lot in humid/rainy weather you can get a lot of condensation build up. Next would be to do a combustion gas test to see if there is any sign in the cooling system. This will give you some of the methods. Many of the tools are available as loaner tools fro the parts chain stores.
https://www.2carpros.com/articles/head-gasket-blown-test
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Sunday, April 22nd, 2018 AT 6:04 PM
Tiny
MELMACK3226
  • MEMBER
  • 7 POSTS
I had already had the plugs changed by a mechanic and no coolant on them. I just read that you should check your oil when engine is cold so I did and I do not see anything on the cap or stick. I only seen it after the car had been running. I do only drive short distances daily. About fifteen minute trips to work there and back. Other than that just to a store or something. The car is never driven for more than thirty minutes. It has been almost a year since last oil change. Should I have it changed to see if it really is milky? I do not know much about cars or really what I am looking for. If not a head gasket, with the symptoms my cars having, do you have any recommendations on what I should try next?
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Sunday, April 22nd, 2018 AT 6:27 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,476 POSTS
Short trips like that do not allow the oil to get up to temperature and boil the water out. With that and close to a year (with your driving habits I would opt for at least two changes a year not based on mileage) I would start with an oil change. You say you heard knocking. Do you still hear it? Next would be to run a scan to see if there are pending faults or if there are hidden codes. (OBDII only states a list of codes that have to be shown, there are hundreds more that can set but not turn on the light.

The knock could be related to the oil blocking passages or another issue. Like a crank angle or cam sensor causing the timing to change.
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Sunday, April 22nd, 2018 AT 7:49 PM
Tiny
MELMACK3226
  • MEMBER
  • 7 POSTS
I have not heard the knock but that may be because I cannot drive it. Like I said, it cranks and idles fine with no hesitation but as soon as I try to accelerate it cuts off. It only made the sound when letting off the acceleration and it was not always constant. I am not even sure if "knock" would be the best way to explain it. I originally thought it was a bad pulley. So will changing the oil stop the sputtering? Would that be caused by a clog somewhere? Also, what is the best way to get a scan done if I cannot drive it. I have already wasted $300.00 trying other things and cannot really afford to pay $100.00 for a mobile mechanic not knowing how much I will be spending in repairs once I find the problem. Based off of what I have told you do you think I should have the head gasket checked or does it sound like something else? Can oil be milky from anything else? Does it necessarily mean head gasket? And if oil was milky would I definitely be able to tell a difference in color?
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Sunday, April 22nd, 2018 AT 8:17 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,476 POSTS
I would start with an oil change. Bad/contaminated oil can cause various problems when the engine has Variable Valve Timing like that engine is. The milky look could easily be just condensation from not being driven. That will sink to the bottom of the oil pan and not show up after the car has been sitting a while as the dip stick is only in the top of the oil. The oil could be causing the camshaft actuators to act up and cause running issues. There are a few makes with similar issues.
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Monday, April 23rd, 2018 AT 1:27 PM
Tiny
MELMACK3226
  • MEMBER
  • 7 POSTS
Okay, I will have it changed and see what that does. Thank you and I hope I do not have to ask anymore questions!
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Monday, April 23rd, 2018 AT 2:50 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,476 POSTS
I do not mind questions, but I hope the next post is that the oil change made a difference and it is running better. If it does not cure it at least one variable is gone.
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Monday, April 23rd, 2018 AT 6:32 PM
Tiny
MELMACK3226
  • MEMBER
  • 7 POSTS
It was a vacuum leak. Had my car back two weeks and now it is running hot. I am not losing any coolant. It gets hot within ten to fifteen minutes, It has also been 95-100° this week. What could this be? I did hear light ticking sound when accelerating on the way home.
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Monday, May 14th, 2018 AT 2:27 PM
Tiny
STEVE W.
  • MECHANIC
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How hot is "hot"? Most engines these days run at 210 degrees or higher. If it is overheating or you see bubbles in the coolant it could still be a head gasket issue.
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Monday, May 14th, 2018 AT 6:38 PM
Tiny
MELMACK3226
  • MEMBER
  • 7 POSTS
I am not sure. The hand goes all the way to the H, car will not start if it is too hot. It does not smoke.
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Monday, May 14th, 2018 AT 7:21 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,476 POSTS
Okay, the first thing to do is verify that it actually is getting hot. A bad sending unit could be causing this. Or if while hunting down a vacuum leak a connector was knocked loose. The other thing would be if the cooling fans are not coming on. Those you should hear when it starts to get hot. For the temperature you could use an IR thermometer to see what it reads compared to the in dash unit.
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Tuesday, May 15th, 2018 AT 7:41 AM

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