Fleeced by dealer. 2.3 Random misfire cool/cold start

[Indy951]

UPDATE: FIXED! Hose assy from air filter are to brake booster was the trick. With warranty expired, I decided to diagnose myself. No codes, other than random misfire, but detailed inspection found a loose joint on the hose assembly running from airbox to brake booster, at the sensor. It has an electrical connector near top of radiator. $140 for updated hose Assy and 10 minute install. Not a misfire since March 2026 (was daily for years).

3rd trip to dealer for random misfire. Only happens at first start of the day, and only last 30-60 seconds. Coolant has never been added since new. 48k miles currently, but misfire started occuring at 15k. No repair has been successful. A DPFE sensor was the diagnosis last week, and the $60 sensor was replaced. $865!!!!! 1 hour of diag, and 2.5 R&R sensor. I was not happy, but kept as calm as I could. Tech brought car around and walked off as I opened the hood. There was the new sensor, minus the two hose clamps in all of it's 900 dollar glory.
Next morning, misfire and CEL reported for duty, just as I had informed the service writer it would.

I've calmed down, and will see service Mgr or GM Monday.

Any ideas about the misfire? I'm afraid to ask for ideas about the Monday meeting....

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[Alanp970]

Isn’t this covered under the powertrain warranty?

 

[Indy951]

Isn’t this covered under the powertrain warranty?

I thought it would be. Or the emissions warranty, but the service advisor just pointed at the screen and said it isn't covered. I have no.way of knowing the labor time ford pays for the sensor, but it can't take more than 15 minutes to swap and 2.5 hours got me pist.

 

[Snacktime]

Replace the coil packs and new spark plugs. You may have fouled then enough that even if you fixed the initial issue you have now gone long enough to have another.

This is like the good old days, cap & rotor, plugs and wires. Everything at once or you're wasting money.

 

[Ducati1098]

3rd trip to dealer for random misfire. Only happens at first start of the day, and only last 30-60 seconds. Coolant has never been added since new. 48k miles currently, but misfire started occuring at 15k. No repair has been successful. A DPFE sensor was the diagnosis last week, and the $60 sensor was replaced. $865!!!!! 1 hour of diag, and 2.5 R&R sensor. I was not happy, but kept as calm as I could. Tech brought car around and walked off as I opened the hood. There was the new sensor, minus the two hose clamps in all of it's 900 dollar glory.
Next morning, misfire and CEL reported for duty, just as I had informed the service writer it would.

I've calmed down, and will see service Mgr or GM Monday.

Any ideas about the misfire? I'm afraid to ask for ideas about the Monday meeting....

Cold start misfires are typically caused by coolant intrusion on 4 cylinder Ford engines.
Not very common for Bronco, but anything can happen.
Borescoping the affected cylinder would probably be one of my first steps depending on what DTCs are being set.

Isn’t this covered under the powertrain warranty?

No. DPFE sensor is only covered under 3/36.
But it may be covered under ESP if the OP has that.

 

[Indy951]

Replace the coil packs and new spark plugs. You may have fouled then enough that even if you fixed the initial issue you have now gone long enough to have another.

This is like the good old days, cap & rotor, plugs and wires. Everything at once or you're wasting money.

It's had the misfire for 2 years. The DPFE didn't fix anything.

 

[Indy951]

Cold start misfires are typically caused by coolant intrusion on 4 cylinder Ford engines.
Not very common for Bronco, but anything can happen.
Borescoping the affected cylinder would probably be one of my first steps depending on what DTCs are being set.



No. DPFE sensor is only covered under 3/36.
But it may be covered under ESP if the OP has that.

 

[Indy951]

Thanks for the info on warranty. If the same problem hasnt been fixed with them throwing parts at it, should the warranty be in play? The misfire is random, but every cyl is showing misfires. It's been doing this for 35-40k miles and I've never added coolant, so I don't have much hope for coolant in cylinder.

 

[Indy951]

Anyone know the labor hrs on KA1ZSL200A replacement? Just the sensor, not the hoses. Thanks

 

[Ducati1098]

Thanks for the info on warranty. If the same problem hasnt been fixed with them throwing parts at it, should the warranty be in play? The misfire is random, but every cyl is showing misfires. It's been doing this for 35-40k miles and I've never added coolant, so I don't have much hope for coolant in cylinder.

Warranty depends on causal part.
If the DPFE didn’t fix it, then they would need to continue diagnosis. not much anyone else can do. What other parts have they thrown at it?

I agree that if it’s showing misfire on all cylinder then it’s likely not coolant intrusion. It may help if you tell us what else they’ve done.

 

[Ducati1098]

Anyone know the labor hrs on KA1ZSL200A replacement? Just the sensor, not the hoses. Thanks

Probably 0.5-0.8 for Ford warranty. I don’t have a computer handy to look it up.
Either way, 2.5 was far too much.

 

[Indy951]

Warranty depends on causal part.
If the DPFE didn’t fix it, then they would need to continue diagnosis. not much anyone else can do. What other parts have they thrown at it?

I agree that if it’s showing misfire on all cylinder then it’s likely not coolant intrusion. It may help if you tell us what else they’ve done.

I don't have the paperwork from the 1st attempt, but it a hose assy if I remember correctly. 2d attempt was different dealer that had it for a week. Ran every test they could, unable to find fault. Plugs were pulled and inspected last week, but the dusty coils showed no evidence that a human removed them.

 

[Indy951]

Probably 0.5-0.8 for Ford warranty. I don’t have a computer handy to look it up.
Either way, 2.5 was far too much.

Thx. I'd be OK with an hour, even. There was no P139C code, but tech noted it was "out of range".

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