What do you guys think is happening with this Fiesta?

[uncleAl]

I am new to the forums here and have been wanting to buy a Fiesta ST for a while and may have found a good deal. Problem is, it's misfiring.

Oil looks good, has Cobb stage 3 tune, 112k miles, 2014, oil changed every 5k miles. Included a Youtube video link of it. Everything is pointing to a possible exhaust leak - when revved, it smells like exhaust in the engine bay. Not sure if this is a normal misfire sound on these. Any opinions would be great!

View: https://youtu.be/C3B0y38TGb0

 

[madhatter]

i'd wager it's a cracked exhaust manifold. Possibly cracked downpipe or a bad exhaust gasket, but i doubt it is a bad gasket.

that's definitely not a normal sound.

 

[Stupidbutt]

is the symposer still there or loose?

 

[Dialcaliper]

That definitely sounds like an exhaust leak, probably at the manifold as mentioned above and not a “misfire” to me. Engine is probably still firing fine on all 4 cylinders as the deeper sound coming out of the exhaust pipe sounds pretty normal

Get about 3ft of garden hose (preferably the black rubber kind that won’t melt as easily) and use it as a stethoscope to probe around the exhaust manifold and downpipe area which can help pinpoint the location of the leak.

 

[uncleAl]

i'd wager it's a cracked exhaust manifold. Possibly cracked downpipe or a bad exhaust gasket, but i doubt it is a bad gasket.

that's definitely not a normal sound.

I think you may be right. I am looking into all options commented on here! Thank you for the input.

 

[uncleAl]

is the symposer still there or loose?
View attachment 64148

I ended up trailering it home yesterday. Going to check this shortly!

 

[uncleAl]

That definitely sounds like an exhaust leak, probably at the manifold as mentioned above and not a “misfire” to me. Engine is probably still firing fine on all 4 cylinders as the deeper sound coming out of the exhaust pipe sounds pretty normal

Get about 3ft of garden hose (preferably the black rubber kind that won’t melt as easily) and use it as a stethoscope to probe around the exhaust manifold and downpipe area which can help pinpoint the location of the leak.

I will certainly try this. I ended up trailering it home so I will be diving in today. Appreciate the input!

 

[Gs1504]

find anything?

 

[uncleAl]

find anything?

It ended up bring a blown spark plug on cylinder 2.

 

[uncleAl]

UPDATE. It ended up being a blown spark plug. I need to rebore as the threads are not salvageable. Does anyone know the proper size to rebore on this 1.6? Everything is pointing towards M12. I am looking at kits like the helicoil and others.

 

[scooter123]

Google is your friend here. It's an M14x1.25 thread (VERY MUCH standard) and you'll need a full helicoil kit for that size. BTW the Helicoil kit includes a special tap that references off the remainder of the existing threads and due to the length the piston in the cylinder you are working on much be at the bottom of the cylinder. It also contains 3 inserts of different lengths and the kit number is 5334-14. It's not cheap but they work better than any knockoff so I always spend the money for Helicoil and regard those who try to cheap out as FOOLS. Because if you F up on this you will find a new cylinder head is a very expensive part to replace. Finally if you are doing this on engine use lots of grease to retain as many chips as possible, and play on filling the cylinder with acetone and vacuuming it out with and Air compressor powered vacuum. BTW, these are commonly contained in a Vacuum Colling System filler kit, another maintenance item I consider essential. NExt you will want to use air thru the spark plug hole to blow dry the cylinder and hopefully blow out any remaining chips. I will also note that once you have that cylinder totally clean a shot of motor oil into that cylinder thru the spark plug hole is needed and you will also need to change the oil immediately because it will have acetone in the oil.

Link to install video

View: https://www.youtube.com/watch?v=-qMpf9O83OQ


PS; alcohol (Vodka), Methyl Alcohol, Rubbing Alcohol, or as a last resort Gasoline are suitable substitutes for Acetone. What you want is a fast drying solvent that will allow the cylinder to dry quickly and completely. Also take note if you are in a humid environment Air Compressors do accumulate water so make sure you run the air long enough to evacuate any water before blowing out the cylinder.

PSS; Yes, on a pushrod engine like the SBC or Ford Windsor I would pull the cylinder head to do this task. Unfortunately Ford doesn't key their Crankshafts and that makes removing the cylinder head a rather time consuming and very precise process. So doing it on car is the easiest approach and with enough effort to insure chip removal you can succeed almost every time. However it is possible to miss a chip and that could result in a scored cylinder or perhaps damage to the turbocharger. So do NOT take any shortcuts on cleaning the cylinder out.

 

[uncleAl]

Google is your friend here. It's an M14x1.25 thread (VERY MUCH standard) and you'll need a full helicoil kit for that size. BTW the Helicoil kit includes a special tap that references off the remainder of the existing threads and due to the length the piston in the cylinder you are working on much be at the bottom of the cylinder. It also contains 3 inserts of different lengths and the kit number is 5334-14. It's not cheap but they work better than any knockoff so I always spend the money for Helicoil and regard those who try to cheap out as FOOLS. Because if you F up on this you will find a new cylinder head is a very expensive part to replace. Finally if you are doing this on engine use lots of grease to retain as many chips as possible, and play on filling the cylinder with acetone and vacuuming it out with and Air compressor powered vacuum. BTW, these are commonly contained in a Vacuum Colling System filler kit, another maintenance item I consider essential. NExt you will want to use air thru the spark plug hole to blow dry the cylinder and hopefully blow out any remaining chips. I will also note that once you have that cylinder totally clean a shot of motor oil into that cylinder thru the spark plug hole is needed and you will also need to change the oil immediately because it will have acetone in the oil.

Link to install video

View: https://www.youtube.com/watch?v=-qMpf9O83OQ


PS; alcohol (Vodka), Methyl Alcohol, Rubbing Alcohol, or as a last resort Gasoline are suitable substitutes for Acetone. What you want is a fast drying solvent that will allow the cylinder to dry quickly and completely. Also take note if you are in a humid environment Air Compressors do accumulate water so make sure you run the air long enough to evacuate any water before blowing out the cylinder.

PSS; Yes, on a pushrod engine like the SBC or Ford Windsor I would pull the cylinder head to do this task. Unfortunately Ford doesn't key their Crankshafts and that makes removing the cylinder head a rather time consuming and very precise process. So doing it on car is the easiest approach and with enough effort to insure chip removal you can succeed almost every time. However it is possible to miss a chip and that could result in a scored cylinder or perhaps damage to the turbocharger. So do NOT take any shortcuts on cleaning the cylinder out.

Thank you so much. Unbelievably helpful. I will post back in here with an update after I have completed the job this weekend. Hopefully it will help someone else with the same blown spark plug issue.