Cold weather knocking during start ups.
 

Firstly, Im going to apologize for not using the search function. Im on my phone and it just won't let me. For the last couple weeks its been frigid with temps between 10-35ºF. When I first turn the car on its knocks pretty hard, maybe about once every 3-5 seconds and gradually diminishing til its gone. I don't have any other idle issues, no dips or random oscillations. I can't figure it out, is there anyone out there that has also experienced this? Anything documented?

Thanks in advance

Yes, I mentioned this in another thread and called it "stumbling".
The engine "stumbles" for a short moment right after I fire it up.
I've had this happen during cold, cold mornings... like today.

Do you know if theres any info out regarding this? Im sure it can't be normal. I just feel like its gonna do it so hard the engine is gonna shit itself

Mine has done this the last couple days with it being really cold. It almost sounds like the engine makes a small cough every 5 seconds or so. Oddly enough if I just engage first and start driving it goes away immediately. It only does it on idle so I just don't let the car sit and idle when it's cold.

Hmm I might check for this today or tomorrow. Only thing I've noticed when cold is that it takes about 5 mins of driving to get warm air out of the vents. Also the clutch feels stiff but I think thats normal.

I havent tried that, ill check it out tmw.


its pretty loud, like you could walk away a good 20-30 feet and hear it :(

Haven't heard knocking but it does stumble a bit when really cold on mine.

is it loud? knocking was the only way i could describe it. SAM TELL ME ITS GONNA BE OK!?!?

Well it wasn't really loud it was more of a idle dip every few seconds but never heard a knocking type sound but I'll pay more attention tomorrow morning.
If it happens to you again just take it to the dealer and use that warranty to be on the safe side.

Mine will stumble once or twice not long after startup on a cold day. It needs to warm up a little to run properly it seems.

Mine doesn't knock but I do hear a difference when it finally warms up. Mine also sounds like it shutters in the deeper cold weather.

My BRZ did this same thing today. I think it has something to do with the chemical composition of the gasoline when the temperature fluctuates so much. I will say, I got horrible gas milage today and am very displeased.

Mine did that once, the first time we had a cold snap. Sounded like something broke under the hood. Never happened again though.

I've been having long start and the stumble as well. I just drive and baby it for a bit until the car warms up. Mine had a screeching sound on a cold start one morning and it sounded like it was running with 0 oil for a few seconds. Scary stuff.