Misfire When Idling

[team_aeroaz]

So I just bought this 2019 Ford Fiesta ST from this dealership. It’s a salvaged restored title and it got hit (if you were facing the car) on the right side, so not even near any engine components and it wasn’t even hit hard either. I drove it for 24 hours and it seemed fine. However, the next morning, I am getting ready for work and I see the check engine light on. I checked the code and it said Misfire Cylinder 1. In my thoughts I was like, no way, because this car only has 38,000 miles on it. So I drove it around for a little bit, did fine, but then when I parked it, the engine light was blinking… I did a little diagnostic trick and switched the coil packs from Cylinder 1 to Cylinder 2, just to see if it was the sparkplugs. Lo and behold, it blew the check engine light for Cylinder 1 again. I just want to confirm because there is absolutely no way this motor is bad at such a low mileage, and the hit to the vehicle wasn’t that strong when it was in that car accident. If my diagnostic is correct, could it either be just a lose spark plug, or a bad sparkplug? It’s just weird because if the car was fixed, the sparkplugs should have been changed. (But by looking at the engine bay, it being so dusty, it probably wasn’t). Let me know your thoughts. Thank you.

P.S. I work 14 hour shifts so I didn’t have time to check the spark plugs. And it happened today this post was made.

 

[FiestaSTdude]

I would definitely pull the plug for cylinder 1 it probably wouldn’t be a bad idea to check compression for that cylinder. Did the car run rough at any point?

 

[team_aeroaz]

I would definitely pull the plug for cylinder 1 it probably wouldn’t be a bad idea to check compression for that cylinder. Did the car run rough at any point?

No it did not, it ran great for the first 24 hours, and the misfiring doesn’t really do anything unless it blinks. When it blinks, taking off is a little rough but once it gets above 1.5k rpms, it’s fine

 

[team_aeroaz]

Update: checked the spark plug on cylinder 1. Looks like it’s wet, possibly oil, this mean I’d have to change out the PCV valve correct?

 

[FiestaSTdude]

Update: checked the spark plug on cylinder 1. Looks like it’s wet, possibly oil, this mean I’d have to change out the PCV valve correct?

I’m not sure what you need to replace, but what if you put a new plug in cylinder 1 and see if that temporarily stops the misfire?

 

[NOVA_Ranger]

Update: checked the spark plug on cylinder 1. Looks like it’s wet, possibly oil, this mean I’d have to change out the PCV valve correct?

Rut roh. Good luck!

 

[SteveS]

If you bought it from a dealership only a day ago, take it back.

 

[NOVA_Ranger]

"there is absolutely no way this motor is bad at such a low mileage"

A lot can happen over the course of 38k miles...

 

[team_aeroaz]

"there is absolutely no way this motor is bad at such a low mileage"

A lot can happen over the course of 38k miles...

I know that, maybe I should’ve put that in the post but please read the update I have posted, thanks 👍

 

[NOVA_Ranger]

I know that, maybe I should’ve put that in the post but please read the update I have posted, thanks 👍

Best of luck. Personally, I'd consider returning the vehicle like Steve mentioned. The problems could get expensive fast, and not a great way to start ownership of a vehicle.

 

[Intuit]

absolutely no way this motor is bad at such a low mileage

I agree that mileage is low. Mod-reversals before sell are common. Programming mods are impossible to see.

 

[team_aeroaz]

Update: Dealership will not take the vehicle back. The vehicle needs a new engine. Guy literally said „Due to hard acceleration, you need a new engine” 🤣. Trying my best to get this situated. Apparently they did not inspect the engine before selling the vehicle and that they’re trying to lie themselves out of it, yet without any proof.

 

[SteveS]

if the dealership won't service the car they aren't much of a dealership. Or shysters who knowingly sold a car with problems. Especially if they are telling you it needs a new engine because they knew it had a cracked head or something.

That said, if you're going to work through the problem yourself, you actually need to make a diagnosis, which is what the dealership's service department should have done. There are plenty of cars which oil-foul plugs that can be repaired. The most common reason is a malfunction in the PCV system. To look further, I'd look at all four spark plugs. Consider compression testing the engine, especially if only one plug is oiled. Check the oil for coolant contamination.

If the plugs are all fouled, it may be the PCV. It can also be a blown turbo seal.