Engine Knock sound issue
 

So I've looked around not haven't found anything similar on our forums, therefore I decided to do a quick write up.

Car: 2013 FRS
Odometer reading: 2200 km
Transmission: Automatic
Issue:
Engine knock sound in the range of 2000-3000 RPM in 3rd/4th gears (loudest points) when engine is warm.
The AC was off at all times.
No check engine light at all.

This issue is most evident when the car is in DRIVE (i do not know why, but its not as pronounced when using paddle shifters) and it is in 3rd or 4th gear in the range of 2000-3000 RPM, most evident at 2500 RPM.

To replicate the issue I usually go onto a slightly sloped road and get the car to aforementioned gear/rpm ratio.

The noise is definitely a knocking sound. If i hold it in that gear/RPM it just keeps knocking away.

This issue first arose at about 700-1000 KM. I had just fueled up at Shell (93 octane) gas station and went on the road. It was so bad that I could hear it over music playing. At the time I thought it was a bad batch of gas. I drove for about 50km and after I got home and let the car sit for 10 minutes and started it again the sound wasn't there.

This happened again 2nd time at about 2000 KM. This time I had different fuel (costco 91 octane) and I've went about 450 km on the duel (was 3/4 empty). Therefore I figured that the fuel is not the issue.

I decided to take it to the dealer today and i managed to replicate the issue on a small scale (the knocking wasn't at it's loudest) but the mechanic agreed that there was an issue. They have ordered new high pressure fuel pump for me and will install it in a week.

On the drive back it started knocking pretty loud again.

It should be mentioned that I've had rough start issue as well about two times since I got the car.

I've found similar issue on Australian GT86 forums:
Here is the link to the thread if anyone is interested: gt86 aussi forums /forum/f16/engine-pinging-rattle-noise-under-acceleration-953/

So has anyone else here experienced this issue and does anyone know what the hell this is?
I highly doubt this is a fuel pump issue as I have 0 crickets under my hood, but from the part order I saw the dealership put in that's the excuse they used.

after lurking a bit more I found out that this issue occurs in a lot of the cars if you dont overrev it and listen to it.

This sounds like exactly the problem I'm having. It started at around 13,000 miles or 21,000 km. It seemed to start after I moved from Ohio, elevation ~600 feet, to Denver, CO, elevation ~5280 feet. We have lower octane fuel here (premium is 91), but the reduced Oxygen level reduces the likely hood of pre-ignition, obviating the need for 93 octane.

I took it to a Toyota dealership, and they couldn't reproduce it. After that they basically said, "Meh." and didn't seem interested in trying further to figure out my problem.

Just like you, driving up a slope exacerbates the problem. Driving up a mountain pass makes it occur pretty much every time.

Did you get your fuel pump replaced? Did it change anything? Have you found any other threads on this? I haven't seemed to find anyone with quite the same problem except you so far. Your explanation is dead on with my problem.

If it's the valves clicking away you're talking about; I have that too. Don't think it's engine knock...

Could this be similar?
http://www.ft86club.com/forums/showthread.php?t=30973

Sounds like a warranty issue but if they can't reproduce it there's nothing to diagnose, you're kind of in a corner.
A video or sound recording would help determine if it's a "normal" noise. Although the tech said it was a problem it's hard to guess over the internet.

so a general update.

the high pressure fuel pump was changed... BUT

I've noticed that it is directly related to the gasoline used.
Costco and Esso 91 gas has a ridiculous knock... 94 Petro Canada doesn't.

I have a full gas of Esso 91 and it was ticking away like a mother *****...
The first time I noticed the noise was from 93 Shell...

I will try to go to Vpower once more after my whole tank is done and see what happens...

I had similar issue occur 3 times over the course of 5000km, I do not think this is the same thing that we speak about thou.

I did think it could be the injectors... so I might push for a change of those...

I'm almost sure this is the problem I'm having. I have a manual and this sound occurs similar to the other post you referenced. Here's what I know for sure --> it only does it when the engine is totally warmed up; it started doing it after I got the ecu replaced due to the cel issue; after mentioning it to the dealership they replaced the fuel pump and this did not fix the issue (in fact, I have louder crickets now, but, that's a totally different issue). It does it on different brands of gas (all 91 octane which is all we have for premium in California).

I think (but I'm a total novice at this stuff) it has something to do with the mapping of the ecu.

I really hate this noise! I'm going to take it to the dealership again and hope they can fix it!

If it sounds like firecrackers going off under moderate acceleration or just by free revving it then it is your DIs

i have the same noise, and i drove 5 BRZ to check if they have the noise . they all have the same noise. i realy need to find a solution for that becasue it is realy piising me off. i think the problem is from the ECU map . it has nothing to do with the fuel.

I'm amazed not one person has asked what the knock sounds like? There are a hundred different types of knocking noise!

My rod bearing started knocking faintly from 2 to 3 k rpm for a few days just before it got real loud and I shut the engine down,...my car is highly modified but I'm hearing of rod bearing failures on stock cars now.

Quick question, where in Canada do you get Shell 93? I've only seen 91. Also, to contribute, if the sound your hearing is a pinging type sound while lightly loading the engine than I would agree that is due to the octane grade of fuel. IMO I think even Petro 94 may be too low/shitty, but is definitely better than any 91. I had a similar experience with pinging during extremely hot weather and 91 octane that I was forced to add an octane booster for the remainding tank which seemed to make the engine wayyy happier, so from that point on I've only ever used Petro 94. My next thing I want to try is race fuel to see if it makes a difference or at least add an octane booster to the 94, which will bring it too 100 octane level.

Spark Knock?
 

Sounds like spark knock(from too low of octane rating) I used to get this in my Nova (13 to 1 compression) FA 20 is 12.5 to 1 compression and could happen if the temp is too high. Cooling and higher octane solved it in my Nova. Try adding some octane booster and see if it stops it. Octane booster is pretty cheap so one try and you will know.