Vacuum Leak? Rough idle

[njweatherman]

I had a simular issue. It was very random. Wouldn't always happen and I would always notice my rpm's slightly drop at a light before going back up. Not a huge difference, but notciable on the digital gauge. This past January during some cold days here I noticed my rpms bouncing a little more and my idle would be higher than usual. I took it to the dealer and they blamed it on the cold weather and told me no codes. I knew there were no codes, but knew something was off. I took it to another dealer 30 mins away. Found out I had a bad spark plug on #2 cylinder that was misfiring without tossing a code. Replaced it and all fixed. They actually took the time to look for the problem unlike the dealer that is 1 mile from my house.

Thank you for sharing. The problem with most dealers is they are too busy. Second, if there are no codes, they don't take the time to search for the problem.

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[NeedForGreen]

Thank you for sharing. The problem with most dealers is they are too busy. Second, if there are no codes, they don't take the time to search for the problem.

Yup sadly most are worthless.

 

[Mrw54]

Hey guys, I just purchased my first mustang(a 2016 gt) and I’m having random rough idle problems that seem to occur more the hotter the weather. I replaced the spark plugs but it still happened. Taking it to the dealership soon to see what they say(I have no codes thrown)

 

[njweatherman]

Hey guys, I just purchased my first mustang(a 2016 gt) and I’m having random rough idle problems that seem to occur more the hotter the weather. I replaced the spark plugs but it still happened. Taking it to the dealership soon to see what they say(I have no codes thrown)

Ahmad,
Welcome to the Mustang world! How far is the dealership from your house? The reason I am asking is because your car may sit for an extended period before they test ride it, and it will not be hot. Make sure to tell them the car needs to be hot for the problem to occur.
Also, did you notice how low your idle goes when it becomes rough? Does it happen at a stop sign or red light? Did you ever stall?

 

[Mrw54]

Hey njweatherman,
The car hasn’t stalled but it has gotten close twice. Once at a light, and once when I was reversing into a parking spot inputting very little gas. I’m taking it to the dealership next week to see if they can figure out what might be the problem. The car does idle at 600 rpm and sometimes at 500 rpm depending on the temp outside. I’m pretty sure it has to do with the maf or map sensor? Or maybe even a dirty throttle body. Rides great otherwise(bone stock)

 

[njweatherman]

Hey njweatherman,
The car hasn’t stalled but it has gotten close twice. Once at a light, and once when I was reversing into a parking spot inputting very little gas. I’m taking it to the dealership next week to see if they can figure out what might be the problem. The car does idle at 600 rpm and sometimes at 500 rpm depending on the temp outside. I’m pretty sure it has to do with the maf or map sensor? Or maybe even a dirty throttle body. Rides great otherwise(bone stock)

What helped my rough idle was cleaning the mass air sensor and throttle body. Since then, the idle has not dropped down to lower than 550 at a red light. However, the car still does shake a bit at a red light after driving for about 1 hour or more for some reason. It may do it once or twice a ride, and then stop. But the car has to be hot and driven for at least an hour before it does it. I don't know why. Please keep us posted with what the dealership finds.

Thanks!

 

[Mrw54]

Can do! Love the s550 thus far tho!

 

[Mrw54]

What helped my rough idle was cleaning the mass air sensor and throttle body. Since then, the idle has not dropped down to lower than 550 at a red light. However, the car still does shake a bit at a red light after driving for about 1 hour or more for some reason. It may do it once or twice a ride, and then stop. But the car has to be hot and driven for at least an hour before it does it. I don't know why. Please keep us posted with what the dealership finds.

Thanks!

Took it to the dealership and they couldn’t replicate it. Not too worried about it at this point if it is completely random.

 

[njweatherman]

Took it to the dealership and they couldn’t replicate it. Not too worried about it at this point if it is completely random.

Ever since I did the throttle body and mass air flow sensor cleaning, it has been much better.

 

[FrankM5]

I decided i was going to go back to stock. I changed it and also wiped the throttle body, gave it a quick clean, i did not use anything besides a paper towel. I did slightly open the flap to get on the backside. After that i made sure everything was plugged in and turned it on. It was idling fine no codes etc, i had my dad take the car to work its about 30 mins there and back so a total of an hour or run time, he said it ran great. I turned the car on today in the morning with remote start, let the car warm up and headed to work it was working fine then, on my way to work i saw the car have a rough idle then a check engine light came on, i checked the ford app and i got no service alerts. I removed the battery for a KAM reset after looking it up, removed the negative terminal and that made the car send the alerts to my phone i got two "alerts"
- The engine control system has reached its adaptive fuel control system limits for an overly rich system"
- The powertrain control system has detected that it is unable to fully open or close the upper active grille shutters"

After connecting the battery back and turning on the car, it immediately hesitated, the cars rpms started to go up all the way to 1.5/1.7 rpm which has never happened before. After a couple of mins it went back down it was at 700 rpms and stayed at 700 rpms with the A/C on. I sat in the car for
30 mins, i did not drive the car within those 30 mins. The check engine light is still on currently

 

[njweatherman]

I decided i was going to go back to stock. I changed it and also wiped the throttle body, gave it a quick clean, i did not use anything besides a paper towel. I did slightly open the flap to get on the backside. After that i made sure everything was plugged in and turned it on. It was idling fine no codes etc, i had my dad take the car to work its about 30 mins there and back so a total of an hour or run time, he said it ran great. I turned the car on today in the morning with remote start, let the car warm up and headed to work it was working fine then, on my way to work i saw the car have a rough idle then a check engine light came on, i checked the ford app and i got no service alerts. I removed the battery for a KAM reset after looking it up, removed the negative terminal and that made the car send the alerts to my phone i got two "alerts"
- The engine control system has reached its adaptive fuel control system limits for an overly rich system"
- The powertrain control system has detected that it is unable to fully open or close the upper active grille shutters"

After connecting the battery back and turning on the car, it immediately hesitated, the cars rpms started to go up all the way to 1.5/1.7 rpm which has never happened before. After a couple of mins it went back down it was at 700 rpms and stayed at 700 rpms with the A/C on. I sat in the car for
30 mins, i did not drive the car within those 30 mins. The check engine light is still on currently

Frank,

If I recall, you only had a Corsa intake on, correct?
I'm hoping others can comment on what, "The powertrain control system has detected that it is unable to fully open or close the upper active grille shutters", means?

 

[Mustangfreek]

I just went thru a little hiccup with my TB clicking, which turned out to be a weak battery problem.

But I ended up taking it off and man was it dirty, and looking in the intake, from the purge and pvc the inside of intake is oily..

Just Added a Upr catch can

Whats the best way to clean the Maf?

 

[Cobra Jet]

I decided i was going to go back to stock. I changed it and also wiped the throttle body, gave it a quick clean, i did not use anything besides a paper towel. I did slightly open the flap to get on the backside. After that i made sure everything was plugged in and turned it on. It was idling fine no codes etc, i had my dad take the car to work its about 30 mins there and back so a total of an hour or run time, he said it ran great. I turned the car on today in the morning with remote start, let the car warm up and headed to work it was working fine then, on my way to work i saw the car have a rough idle then a check engine light came on, i checked the ford app and i got no service alerts. I removed the battery for a KAM reset after looking it up, removed the negative terminal and that made the car send the alerts to my phone i got two "alerts"
- The engine control system has reached its adaptive fuel control system limits for an overly rich system"
- The powertrain control system has detected that it is unable to fully open or close the upper active grille shutters"

After connecting the battery back and turning on the car, it immediately hesitated, the cars rpms started to go up all the way to 1.5/1.7 rpm which has never happened before. After a couple of mins it went back down it was at 700 rpms and stayed at 700 rpms with the A/C on. I sat in the car for
30 mins, i did not drive the car within those 30 mins. The check engine light is still on currently

From your description alone, it sounds like you may have either an Intake issue (IMRC), or VCT.

The IMRC shaft failure is the most common, which will affect drivability. 99% of the time, the IMRC failures are due to the broken shaft. Looking at images of the shaft, the break is occurring because the diameter of the shaft is too small for the torque being applied by constant activation. See this thread where another M6G member repaired the broken IMRC shaft using JB Weld and it was fully functional again after the repair.
https://www.mustang6g.com/forums/threads/our-first-dtc-p0308.160243/

---

VCT issues:
The VCT solenoids - operational issues can happen at any time. Usually debris gets into the solenoid which could cause idle stumbles. Changing oil can flush out the debris or the Ford Service Center has a procedure that will flush out the VCTs without an oil change. I don't think a Service Center will do this voluntarily, only if a VCT code exists.


Here's (2) threads for VCT info that I had previously posted in other threads:
https://www.mustang6g.com/forums/threads/2015-2021-s550-5-0’s-ssm-50067-vct’s-again-various-dtc-codes.169419/

https://www.mustang6g.com/forums/threads/p0018-code.123932/

--

You say the check engine light is on, but don't list any codes, have you extracted the codes? Do you have a scan tool to get the codes? If not, you can usually get Auto Zone or Advance Auto to scan and tell you the code # and definition. You can also extract stored codes from the gauge cluster. Here's some links to help you pull codes using Engineering Test Mode from the dash cluster.

If you have a 2015-2020+ with the ANALOG gauge cluster, you should be able to enter the “Engineer Test Mode”.

Follow this link:
https://www.mustang6g.com/forums/threads/engineering-test-mode.27581/

If you you have a 2018-2020+ with the DIGITAL cluster, you should be able to access the same test mode found here:
https://www.mustang6g.com/forums/th...n-18-digital-dash-old-way-doesnt-work.115231/

 

[FrankM5]

Frank,

If I recall, you only had a Corsa intake on, correct?
I'm hoping others can comment on what, "The powertrain control system has detected that it is unable to fully open or close the upper active grille shutters", means?

Yes i had a Non tune Corsa Intake

 

[FrankM5]

From your description alone, it sounds like you may have either an Intake issue (IMRC), or VCT.

The IMRC shaft failure is the most common, which will affect drivability. 99% of the time, the IMRC failures are due to the broken shaft. Looking at images of the shaft, the break is occurring because the diameter of the shaft is too small for the torque being applied by constant activation. See this thread where another M6G member repaired the broken IMRC shaft using JB Weld and it was fully functional again after the repair.
https://www.mustang6g.com/forums/threads/our-first-dtc-p0308.160243/

---

VCT issues:
The VCT solenoids - operational issues can happen at any time. Usually debris gets into the solenoid which could cause idle stumbles. Changing oil can flush out the debris or the Ford Service Center has a procedure that will flush out the VCTs without an oil change. I don't think a Service Center will do this voluntarily, only if a VCT code exists.


Here's (2) threads for VCT info that I had posted in that other thread today.
https://www.mustang6g.com/forums/threads/2015-2021-s550-5-0’s-ssm-50067-vct’s-again-various-dtc-codes.169419/

https://www.mustang6g.com/forums/threads/p0018-code.123932/

--

You say the check engine light is on, but don't list any codes, have you extracted the codes? Do you have a scan tool to get the codes? If not, you can usually get Auto Zone or Advance Auto to scan and tell you the code # and definition. You can also extract stored codes from the gauge cluster. Here's some links to help you pull codes using Engineering Test Mode from the dash cluster.

If you have a 2015-2020+ with the ANALOG gauge cluster, you should be able to enter the “Engineer Test Mode”.

Follow this link:
https://www.mustang6g.com/forums/threads/engineering-test-mode.27581/

If you you have a 2018-2020+ with the DIGITAL cluster, you should be able to access the same test mode found here:
https://www.mustang6g.com/forums/th...n-18-digital-dash-old-way-doesnt-work.115231/

Niether AutoZone or O'Reilly could check the codes, I went to a near by shop and used their tester, they did not give me the codes but they went to look them up and came back with
- The engine control system has reached its adaptive fuel control system limits for an overly rich system"
- The powertrain control system has detected that it is unable to fully open or close the upper active grille shutters"

So whatever the ford app gave me was the same thing the scanner tool gave me in terms of "codes" descriptions.

I had them reset the Check engine light, after i did the relearn after the restart the car drove fine on the way home, no idle problems or anything. Today also no issues, idle was fine etc. Im not sure how the ford app works with codes and such but hours after the clear cel it was still showing up under vehicle status on the app until this morning.

Im hoping the car adjusted to the intake even though the corsa should be the same since its a no tune intake.

As for the broken shaft, what are other indicators that i should notice, this sounds like it would happen while driving as well?

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