Engine missing at low idle

Tiny
KRISMANTEN
  • MEMBER
  • 2015 FORD FUSION
  • 4 CYL
  • AUTOMATIC
  • 47,000 MILES
This car has a low idle miss, with or without a/C on (seems to be worse with climate control on). It also does it sometimes while driving. Check engine light is not on. Changed throttle body, mass air flow sensor, plugs, coils, fuel, checked for vacuum leaks. It runs good ninety percent of the time, engine has even stopped a few times at low idle.
Wednesday, November 29th, 2017 AT 11:07 AM

13 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Can you check the actual idle speed? The IAC may be setting the base idle to low and if this is the case the engine will stall and falter with any added load applied a idle. Run a scan as not all codes will set a check light. A scan should pick out the misfiring cylinder and that can also be a help in diagnosis.
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Wednesday, November 29th, 2017 AT 1:10 PM
Tiny
KRISMANTEN
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  • 3 POSTS
As of today scan will not pick out missing cylinder. The car is equipped with electric throttle body which I have changed. I was not aware of a idle air control valve that is separate from throttle body on the car if you can tell me where it is. That is what I thought as well the load on the engine exceeds the idle requested by the PCM.
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Wednesday, November 29th, 2017 AT 1:54 PM
Tiny
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It will be part of the throttle body normally but I will confirm and post back a little later.
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Wednesday, November 29th, 2017 AT 5:58 PM
Tiny
KRISMANTEN
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  • 3 POSTS
We have actually changed the throttle body off of one that ran fine with this one and it made no difference, this vehicle has had the motor changed though. Not sure if that would make a difference.
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Thursday, November 30th, 2017 AT 9:22 AM
Tiny
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You may be looking at a fuel related problem, due to incorrect fuel pressure, or dirty or malfunctioning injectors, also ensure that there are no vacuum leaks.
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Friday, December 1st, 2017 AT 8:15 PM
Tiny
JASON MARCUM
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  • 4 POSTS
We adjusted the timing and it helped a bit not a lot. Also found out that it had been hit close to the harmonic balancer on the engine. Does this sound like a harmonic balancer problem?
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Saturday, January 27th, 2018 AT 7:29 AM
Tiny
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You changed the timing? What did you do?
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Saturday, January 27th, 2018 AT 2:28 PM
Tiny
JASON MARCUM
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  • 4 POSTS
Sorry I wasn't really the one who worked on it, don't know if I'm explaining it right. He adjusted the timing underneath the harmonic balancer. It was just a bit off the mark. It didn't change anything though. Did he do something wrong by doing that?
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Monday, January 29th, 2018 AT 6:42 AM
Tiny
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Depending on what he did, there is no ignition timing manual adjustment, it is all controlled by the PCM, the valve timing is critical, you cant play about with the timing it must be set correctly, if he has checked and corrected any misalignment and re set the valve timing correctly that is ok, I really need to know what he did, if valve timing is out to far you can do serious damage to the engine.I will need some more info on the engine size and the VIN would also help, with this I can send pics of the correct valve timing specs.
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Tuesday, January 30th, 2018 AT 1:48 AM
Tiny
JASON MARCUM
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  • 4 POSTS
Ok I will tell you all the details I know. We are a car dealer and we bought it off of a guy who put a motor in it, he says that it is out of the same model year fusion and am pretty sure that he put a harmonic balancer on it as well. It has always ran this way, possibly a bit better than when we got it. We have did all of the above as I mentioned in the first post. We recently took it to a ford dealer, they said that there was a fraction of a misfire on all 4 cylinders. Now lately it has been missing when driving as well, at 2000 rpm. It is also hard to start when it is cold, it will turn a couple of times and stall. The engine is a 2.5 and the vin number is 1fa6p0h74f5124118. Its a 2016 fusion
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Wednesday, January 31st, 2018 AT 11:33 AM
Tiny
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Ok, I think I know what is going on here, if the harmonic balancer was removed, the mechanic would have needed a number of special tools. There is no key way and the balancer is assembled with friction washers that can't be re used, the valve timing needs to be set up with special locking tools, often these are rather expensive and general work shops cant afford to purchase these. So I need to know if the harmonic balancer was removed and if new friction washers were used and all the cam location locking tools were used, if not, the valve timing will be out and this will have to be re set correctly and new friction washers used, it is a very involved job and any error can cause many drivability and engine performance problems.
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Thursday, February 1st, 2018 AT 1:07 AM
Tiny
JASON MARCUM
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I can just about assure you that neither our mechanic or the one who sold us the car had these tools. Do you happen to know the part number to these washers and the tools that we would need? Also would it be ore cost effective to take it to a dealer and have them to do this, or buy a good used engine and have it put in?
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Thursday, February 1st, 2018 AT 6:28 AM
Tiny
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The tooling will be very expensive, ring a dealer and tell them that the valve timing may have been altered but to work that had been done and ask for a quote, and get a quote for a motor from a wrecker and see what is most cost efficient, it may be cheaper to get a dealer to do a valve timing check, I am concerned that this is the rot cause of your problem
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Thursday, February 1st, 2018 AT 12:28 PM

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