Advice needed based on my recent diagnostics of my mustang's engine misfire issue

[5eku]

Hi all, looking for some insight or advice before I make a major decision. I’m the original owner of a 2018 Mustang GT with 42,000 miles fully paid off.
The only modifications that I have in this car are resonator delete, springs/wheels, and ducktail.
Car is mostly used for daily driving of 60 miles total per day through LA traffic. Never tracked.

Early this year there's been some oil leaks in this car so I've got that fixed from a reputable shop nearby, and not too long after my car just started having some misfire issues. I brought it back to them to do a reset and brought back the car home. We were advised to get the internal timings replaced, and that the car is still drivable as long as I don't push it hard. I was able to drive it very moderately for few months just to get around the city but the issue started appearing again.

I took the car back to Ford dealership to get it checked:

Note that I didn't do any internal modifications aside from what's listed (honestly). could it be because of our jump start attempt due to battery issue at one point?


I'm currently considering selling the car as-is or attempt the repair, I got a quote from another shop for $5.8k of labor.
I like the car since it's fully paid off and wanted to keep it, but if reliability will be in question then maybe it's SOL.

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[GrabberBargeCaptain]

Bump for you, but also 25k for an engine replacement? What is that 10k in labor? Thats kookoo. Curious as to why they think you're tuned/ignition counter is low if you're the original owner.

 

[Weyland-Yutani]

I mean, you know it’s a specific camshaft. I would at least replace the VVT solenoid (and/or maybe cam sensor) before dropping $25K or giving up.

Also, don’t assume a dealer tech is an “expert”.

 

[Skye]

It reads the initial repair shop inserted more problems while attempting to fix the initial faults.

Answers to the questions below will clarify a few things for us. Getting some more details could help us give you additional ideas. $6000-$25000K is a big window. Not even in the same ballpark. I suspect the former quote involves replacing some items(?), while the latter was listed as replacing the entire long block.

Thanks.

Early this year there's been some oil leaks in this car so I've got that fixed from a reputable shop nearby, and not too long after my car just started having some misfire issues.

Where was oil leaking from? What areas?

...and not too long after my car just started having some misfire issues.

Is there a warranty involved with their repairs? Or, maybe their warranty period is over.

I brought it back to them to do a reset and brought back the car home.

Can you explain that further? What was reset? Could this be why the near zero key cycle counters?

Note that I didn't do any internal modifications aside from what's listed (honestly).

No physical internal modifications. Check. Was a tune on the car?

We were advised to get the internal timings replaced, and that the car is still drivable as long as I don't push it hard.

Can you detail "internal timings"? Cams? Timing chains? Electronics? Sensors?

I got a quote from another shop for $5.8k

Did they give you a detailed quote, with any kind of warranty? Did they explain what the $6K involved?

 

[Excelerater]

Ford had lots of 2018s with bad engines,Mustangs and F150s.....Let them play dumb huh
Then they said modded u the engine with a tune but no proof...?

25Gs for a new engine is insane ,its too bad you took it to the dealer,they want to bend you over
If it were me id trade it in or run it off a cliff

 

[5eku]

It reads the initial repair shop inserted more problems while attempting to fix the initial faults.

Answers to the questions below will clarify a few things for us. Getting some more details could help us give you additional ideas. $6000-$25000K is a big window. Not even in the same ballpark. I suspect the former quote involves replacing some items(?), while the latter was listed as replacing the entire long block.

Thanks.



Where was oil leaking from? What areas?



Is there a warranty involved with their repairs? Or, maybe their warranty period is over.



Can you explain that further? What was reset? Could this be why the near zero key cycle counters?



No physical internal modifications. Check. Was a tune on the car?



Can you detail "internal timings"? Cams? Timing chains? Electronics? Sensors?



Did they give you a detailed quote, with any kind of warranty? Did they explain what the $6K involved?

1. when I took it back there it's due to my car's leak and here's what they did:
- oil & filter change
- Replaced valve gasket covers
- Clean off affected areas

from their report: "found valve cover gaskets have heavy leak, oil pan gasket leaking, timing cover gasket minor leak".

2. If it's from the previous shop then yeah, they do.
3. from what I know it's just the ECU reset as is, just to get rid of CEL.
4. Nope no tune, just lowered the car as is.
5. And yeah mostly the timing chains but I can try to get more info.

 

[Skye]

So it seems maybe the car was run low on oil for a period of time, and that might have been the root cause of the internal damage. IDK. I'm speculating.

It's after-the-fact. I understand. It's my belief they could have cleared the codes with a OBD device. If they later returned, it hints to a repeating problem.

Any details might help. Those who've worked some of the more significant and in-depth matters might be able to give feedback how good the $6K number is.

 

[5eku]

So it seems maybe the car was run low on oil for a period of time, and that might have been the root cause of the internal damage. IDK. I'm speculating.

It's after-the-fact. I understand. It's my belief they could have cleared the codes with a OBD device. If they later returned, it hints to a repeating problem.

Any details might help. Those who've worked some of the more significant and in-depth matters might be able to give feedback how good the $6K number is.

Even back then when I bought it to my routine maintenance with Ford, they noted and addressed the Misfiring issues on some cylinders (I can check), and for the past 3 years I haven't really driven the car hard since I've mostly been WFH, which is explains the really low mileage. 2023-2024 I probably just drive it for like 10-15 mins per day just to get in and out of the gym lol.

Cause was running normally without any system bleeps, until I finished paying it off and then the oil leak started appearing when parked, and that's when we took it to the shop to get inspected or fixed. They had to takeout the engine and clean since the oil leak as all over.

just to be self aware, I feel like the probable cause might be I drive the car before it gets heated up properly after cold start, this is because of the apartment that I've rented back then for years and I didn't want to annoy the people around if I idle for too long.

Also, the Ford dealership offered 14k for it if I want to trade it in.

 

[volcanogod]

Bump for you, but also 25k for an engine replacement? What is that 10k in labor? Thats kookoo. Curious as to why they think you're tuned/ignition counter is low if you're the original owner.

The $25k is for the Voodoo engine. This doesn't include labor, is my understanding.

 

[Dsand300]

Ford had lots of 2018s with bad engines,Mustangs and F150s.....Let them play dumb huh
Then they said modded u the engine with a tune but no proof...?

25Gs for a new engine is insane ,its too bad you took it to the dealer,they want to bend you over
If it were me id trade it in or run it off a cliff

I am the third owner of a 2018 Mustang GT Premium with a dealer installed Roush supercharger kit.

The original Coyote Gen III engine was replaced for the original owner under Roush warranty in January 2020 with 6037 miles by the dealership who sold the car and installed the supercharger kit. I purchased the car with 8533 miles in April 2024 from the same dealership. The second owner only put 2500 miles on the car from 2020 - 2024.

I did have to replace the passenger side catalytic convertor in the fall of 2024 under Ford factory warrantee. This may have been the result of the failed engine. I have logged about 10000 miles since the purchase in 2024. Mileage now is 18800 miles.

Vehicle has been relatively trouble free after replacing the 2017 GT350 analog throttle body with a 2019 Mustang Bullet digital throttle body and latest Roush tune per the suggestion of Roush technical service this spring. The vehicle was intermittently throwing codes PO120 & PO124 before replacing the throttle body and updated tune.

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