Mustang 6th gen RPM drops with ENG stops

[Tom4]

Hi guys,

I am owner of Mustang S550, 5L V8 with automatic transmission y.2018. VIN 1FA6P8CF2J5152005 still under Ford warranty.


Car has approximately 35k km (21,5k miles). A few weeks ago my car started to have problems with RPM which I will try describe here:

-RPM sudden drops, in P, N, R or D shift selected

-in slow car speed engine sudden stop working in D shift. (RPM falls to 0)

-RPM strong fluctuation from 600r/m to 1100 r/m with engine/car vibration


This issue usually will appear after a few km of drive, sometimes very fast after start up. But usually engine have to be in operation temperature then this issue starts to appear.


A week ago, my engine indicator appeared so I contacted Ford service. Under warranty they found out failed GPF sensor which was changed and engine “drive” unit was updated with actual version of software.


Today I took out my Mustang from service but engine/rpm issue start to happen again. During the drive in very slow speed to my garage in D mode, engine stopped by itself. Just RPM drops to 0.


I checked few forum topics and discussion similar to this issue, but most of them was about 5th generation of Mustangs, but many this RPM drops was because of failed Canister Purge Valve. For example this video could be nice troubleshooting manual to my issue, but still it is older version of car:


So, my questions are:

What do you think about this issue, what can be a reason?


Is there possibility to check if the Canister Purge Valve is failed by myself?


In Ford service they told me that they need “engine” indicator for warranty apply, otherwise I have to pay for diagnostics or some Purge Valve change? (Problem is that this issue not usually appears immediately, just randomly during the ride)


Many thanks for you help, and I wish you all the best,

Sincerely Tomas

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[brianbr]

Make sure the vacuum lines are pushed on all the way and the intake clamps are tight if you haven't yet.

 

[Tom4]

Make sure the vacuum lines are pushed on all the way and the intake clamps are tight if you haven't yet.

Thanks for answer. Today I will check your idea and valve from video.

 

[WildHorse]

Any mods? If not, sounds like a throttle body problem.

 

[Tom4]

Any mods? If not, sounds like a throttle body problem.

No mods at all. I did not touch car at all. Still under warranty.

Do you know how to diagnose this issue?

Thanks for advice

 

[WildHorse]

Do you know how to diagnose this issue?

Bring it back to the dealer if it's under warranty. Cause really you need a scanner to diagnose it. I believe Ford had a TSB about it.

 

[Andrew@Lethal]

Hi guys,

I am owner of Mustang S550, 5L V8 with automatic transmission y.2018. VIN 1FA6P8CF2J5152005 still under Ford warranty.


Car has approximately 35k km (21,5k miles). A few weeks ago my car started to have problems with RPM which I will try describe here:

-RPM sudden drops, in P, N, R or D shift selected

-in slow car speed engine sudden stop working in D shift. (RPM falls to 0)

-RPM strong fluctuation from 600r/m to 1100 r/m with engine/car vibration


This issue usually will appear after a few km of drive, sometimes very fast after start up. But usually engine have to be in operation temperature then this issue starts to appear.


A week ago, my engine indicator appeared so I contacted Ford service. Under warranty they found out failed GPF sensor which was changed and engine “drive” unit was updated with actual version of software.


Today I took out my Mustang from service but engine/rpm issue start to happen again. During the drive in very slow speed to my garage in D mode, engine stopped by itself. Just RPM drops to 0.


I checked few forum topics and discussion similar to this issue, but most of them was about 5th generation of Mustangs, but many this RPM drops was because of failed Canister Purge Valve. For example this video could be nice troubleshooting manual to my issue, but still it is older version of car:


So, my questions are:

What do you think about this issue, what can be a reason?


Is there possibility to check if the Canister Purge Valve is failed by myself?


In Ford service they told me that they need “engine” indicator for warranty apply, otherwise I have to pay for diagnostics or some Purge Valve change? (Problem is that this issue not usually appears immediately, just randomly during the ride)


Many thanks for you help, and I wish you all the best,

Sincerely Tomas

Seems like a hard one to chase down. If your car is under warranty I would take advantage of it have Ford find it and fix it. They have the diagnostic tools to find and solve the problem.

 

[Tom4]

Thank you for advices, I will definitely contact my Ford service.

Meanwhile, I checked the Evap. Purge Valve in accordance with the video before, and everything was correctly. Once the device was connected to el. power there was suction, once I disconnect it from electricity, the valve remained closed with out suction. -> if I am correct this is correct function and valve is fine.

I was able to make a short video of issue, with out RPM drop or engine stop, just the car has strong vibration and fuel/air ratio was fluctuating. Pls check:
https://vimeo.com/user2794547/review/444984418/c28a78cbb7

Of course I am going to contact Ford tomorrow but I am asking your advices, because the problem is, that this issue is not appearing every time and I am afraid that once car will be at the service it will not happen at all.

Many thanks and I wish you all the best,
Tomas

*Is there any way how to check failed/wrong Throttle body?

 

[drive_55_not]

A few of the members here, me included have had wierd stalling issues,, they are usually VCT related..

My 2018 had no CEL or codes so it would've been a waste of my time to have it looked at under warranty.

Data logging showed the drivers side was the issue just from the AFR on bank 2 going all over the place, I replaced both drivers side solenoids and it quit stalling ...

.

 

[msweet]

A few of the members here, me included have had wierd stalling issues,, they are usually VCT related..

My 2018 had no CEL or codes so it would've been a waste of my time to have it looked at under warranty.

Data logging showed the drivers side was the issue just from the AFR on bank 2 going all over the place, I replaced both drivers side solenoids and it quit stalling ...

.

My car is the same. How hard is it to change the solenoids? If it doesn't require re-timing then I might get my mechanic to just do it

 

[drive_55_not]

My car is the same. How hard is it to change the solenoids? If it doesn't require re-timing then I might get my mechanic to just do it

Pretty simple, pull the valve cover and R&R the solenoids.

I used the Echlin brand from NAPA .. $75 for both.

.

 

[Tom4]

Hi guys,

so car picked up from service today. Result: "engine VVT fail on a row of cylinders A".

Just drived only a few km because of snow here. Hard to say if it helped so far.

Everything was repaired under the warranty.


Interesting arcticle:
Symptoms of a Bad or Failing Variable Valve Timing (VVT) Solenoid
1. Check Engine Light comes on
2. Engine oil is dirty
3. Rough engine idle
4. Decrease in fuel economy

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