Sounds like knocking or miss firing at cold start. Anyone else have this occur?

[RacerX33]

Greetings all.
I have a 24 ST just a little over 5000 miles. Built January 2024. Was a dealer demo had 3400 miles on it when I got it in April.
Every time I do a cold start, if its been sitting over night or even just a few hours,
I hear what sounds like misfiring or maybe knocking is a better description. Its not super loud and Ive heard it ever since I bought it.
Its louder now with the performance exhaust but its always been there. Also in the mornings I get white smoke.
Not much and only for about 20 seconds and it clears.
The knocking/misfiring goes away in about a minute.
Has anyone else run across the noise? Ive been running premium gas and it still does it.
Im not too concerned about the smoke at this point because its not much. It could be steam?
Not big clouds like ive seen in videos.
But the knocking or what ever it is at start up has me concerned.
Or is it a common thing? Like the computer is trying to straighten out the fuel mix on a cold start?
Or is the knocking a sign of trouble?
Im taking it in to the dealer Monday to have that looked at and gen maintenance.

 

[EDWYER]

Yes the knocking really concerns me.

More info.
https://www.explorerst.org/threads/white-smoke.7087/

 

[Drsobczakst]

So it could be a number of issues....
1. These things are known to have bad purge values or issues with the emissions system for fuel that has known to cause hard starts... mine did this a few times and then i go a check engine light. I ran it for codes and got a P0456 (EVAP system leak detected , very small leak). so I cleared the code, cleaned the gas filler door area when the filler neck goes into, they located the purge valve connections (found a diagram online) and rotated the fittings in place while they were connected and checked to ensure they were still clipped in place. I haven't had any issues with this since then. If the purge valve breaks they tend to break stuck open and therefore you have a vacuum leak in the system that caused the hard idle that you feel. (side note, you might not have a check engine light b/c they system does checks depending on pre set perimeters like driving conditions and times. the most common is 30 mins into a drive. What happens is, if there is an issue at start-up, it will log a pending code and then when the system runs that second check and it sees the same issue, it will turn it to a perm code and put the CEL on the dash for you. If the system does not see the issue in the secondary check, it goes away and you never know.)

2. Another issue is, bad turbo seals and it can happen with very little miles on them too. When they start to go bad they leak into the hot side of the turbo as the car sits, then when you go to start it, it burns the oil off and you see the smoke on start up. When they fully let go you get the smoke show you are talking about. mine has been doing this as of late and I'm going to take it in here soon to have them check it. If the shop does it right, they will let the car sit over night and then cold start it so they can see if its happening. (MAKE SURE YOURES DOES THIS TOO). if it does some, they should pull the downpipes off the back of the turbos and check then housings. if the seals are bad, they will be signs and if really bad, there will be oil in them. This doesn't necessarily have to be done cold but should so they can see the pooling of oil. If its been doing it for a while it wont matter b/c they will be able to tell anyways LOL! (Side note on this one, let your ST sit overnight and do a remote start on it. stand behind it and record the start up and see if you can smell burning. this will for sure tell you if its just condensation or oil... you will know the difference!)

Let us know what happens.

 

[powerboatr]

Good thread
Mine for first 30 to 45 or so seconds sounds like hydraulic lifters not getting enough oil
But since we are overhead cam...it can't be
After that's it's smooth and quiet
Out back it has a nice tone...then that tends to soften.

 

[Drsobczakst]

Good thread
Mine for first 30 to 45 or so seconds sounds like hydraulic lifters not getting enough oil
But since we are overhead cam...it can't be
After that's it's smooth and quiet
Out back it has a nice tone...then that tends to soften.

Yeah, I think people tend to forget about the cold start fuel mapping that all cars have no matter what (gas engines anyways)
So depending on how "cold" the motor and fluids are dictates the starting fuel calculations. If the motor is cold from the night before, it will dump more fuel into the cylinders, the motor will hang at higher RPMs and you will have a "beefier" exhaust note. There is a lot of science behind this however, the simplest explanation is... The car needs to get up to proper operating temps as fast as it can. The cold air calls for more fuel, more fuel means higher RPMs and the chain of events continues until the car reads what it wants from internal temp sensors. There is always the chance that you will hear a bit more "chatter" at start up no matter what and 99% of the time its all normal. I spend my spare time running a pit crew for a private racing team with a 2100hp Fox body mustang and we always say, "if it gets louder with more RPM, we have an issue!" These SUVs have knock sensors in them and if something was really off, they would throw a CEL on the dash for sure!

I still stand by my comments above to the original post, I think he is dealing with a possible EVAP issue and or leaking turbos.

 

[dabro68]

New member here, but a longtime Explorer owner, this is my fourth one over the years. I have a 2024 currently with about 7000 miles on the clock. This is my first Ecoboost engine, definitely is a lot more going on than a natural aspirated engine. I never really noticed the noise inside the car, but the first time my wife started it while I was in the garage, I definitely noticed the startup noise, didn't sound good. I do not see any smoke however. The phasers rattled a bit and yes, it sounds just like hydraulic lifters before they're pumped up. Sounds like it's very slow to build oil pressure.

So, after scouring the internet for this issue, I did come across the way the oil filtration is setup on this motor. The top mounted cartridge filter is allowed to drain all the oil back to the sump. So it does take a bit of time for the oil pressure to build. Does it hurt the engine? I don't know, but it can't be good for it, just for the convenience of a top mounted filter cartridge. I found a company, Baxter Performance, that makes an adaptor that allows a spin-on filter and also has a check valve built in that will hold the oil up in the top of the engine. I installed this adapter, it is extremely well made, it works. The slight phaser rattle is gone but the "lifter sounds" remain.

The "lifter noise" lasts right at 25-30 seconds consistently. It sounds kind of "ringy" like it's in the exhaust.

I just returned from a 4000 mile trip to the east coast, attended the ST SUV Experience in Asheville, NC. BTW, I could not recommend this more, it was a blast! At this event I listened to as many different ST's as I could start up. They all make this 25-30 second noise. So I would call this noise normal, my ST ran perfectly every inch, achieved 24-26 mpg, used no oil. I was pleased.

As to what's going on, I would like to know.

Possibly could be in open loop with the O2 Sensors and running rich for those few seconds?
Any kind of bypass in the turbos during startup?

If anybody has an answer, I would love to hear it.

Sorry for the ramble, just my two cents
Dave

 

[RacerX33]

Well, shes been to the dealer. They dropped the exhaust and the down pipes, checked for oil.
Nothing. They found nothing. They said the "smoke" was moisture, and unburnt fuel.
The subtle knocking at startup was told is normal for this vehicle.
They found no problems. Ive never found oily residue on the tips. Just carbon.
I'l keep an eye on it.

 

[FORZDA3]

…scouring the internet for this issue, I did come across the way the oil filtration is setup on this motor. The top mounted cartridge filter is allowed to drain all the oil back to the sump. So it does take a bit of time for the oil pressure to build. Does it hurt the engine?
Dave

This is all bullshit as usual “from the internet”. Yes the oil filter is in a convenient location, but it, as all modern oil filters, has an anti drain-back valve. There is an o-ring on the shaft that goes through the filter that seals it from draining back into the pan along with allowing the filter to drain when it clears the seal area when removing the filter. It sometimes amazes me how much bullshit is floating amongst the “people”.
Note and carry on.

 

[Stone17]

Cam Phase can make noise after sitting all night. Loses oil pressure.

 

[WaferTech]

GM seems to have similar issues with their Direct Injection gas engines.

 

[ZFGracing]

There is a lot going on during cold start on these. It's all for cold start emissions reduction.

1) the di pressure is very high relative to normal idle. This is due to the split injection strategy used by Ford to reduce emissions. That's the louder than normal ticking/ knocking sounds

2) The car is running at -10 to -20 degrees of timing. This is in order to light the cats off. Running at negative timing builds heat in the cats faster. This is the misfire ish sounding grumble in the exhaust.


It's all normal, and no, this stuff cannot be shut off with a tune they are critical emissions related tune items.

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