Low RPM slight knock & rattle
 

Hey guys,

Last week I purchased a 2013 Scion FR-S with 49,000 miles on it as my college car (junior) Yesterday I noticed it dipping low on rpm (down to 500 or less) after any revving and generally sounding rough. Today though, it started knocking when I'd accelerate from around the 500 rpm mark. I'm not any sort of mechanic, but it sounded like a light knocking. However, the car accelerates fine (even though I have nothing to compare it to) and doesn't seem to make any noises above 1,000. In the video, you can tell it sounds weird on the cars left side, although I couldn't actually get a video of it "knocking". Let me know what other videos I can get and what you think it could be, or if I'm just worrying too much.

EDIT: working on uploading the video

im betting on crickets..


sound anything like this??


[ame]https://www.youtube.com/watch?v=oTJfY7mZPUM[/ame]

The 2013 has had a few firmware updates that address unstable idle. I got a 2013 in October and it was on the original firmware and didn’t idle well at all and would actually stall when people shine in the clutch and letting the revs drop rapidly. Within the first week of ownership I got a Tactrix cable so I could update to the latest compatible firmware. Even then it doesn’t idle very well for the first 200 miles after an ECU reset.

I wouldn’t be surprised if your ECU was reset by the previous owner. If that is the case it will probably sort itself on it’s own. The knocking sound is another story. I will have to hear the video.

AT or MT?

Sorry guys, still working on a good knocking video. I should have it by tomorrow (I'm not home atm). The only thing involving the ECU would be that I removed a battery terminal (negative side) because I got a check engine light from accidentally removing the ECU fuse (which is right next to the passenger window fuse). Here is a pretty terrible video from earlier today from my school parking lot. Let me know what you want to see in a video and where I should put the mic.

https://photos.app.goo.gl/0YtEtLz2COOn76C73

For clarity, it is a Manual Transmission. I'm running 0w-20 (fuel economy oil from Mobile 1) and 93 octane. Immediately after getting the vehicle, I changed the oil and filter. Besides the oil looking sortof green, and the oil seal not being lubricated, nothing was odd about it. I really appreciate the help guys.

I held off until seeing your reply. I'll ask again to be absolutely sure. Did you mean to actually say you are operating the engine, asking it to do work all the way from 500 RPM?

Oh, it sounds like a FA20 engine running to me.

As what I think Ultramaroon is getting at is to give the engine some more gas before you let the clutch out.

Good luck with your studies ….. :thumbsup:


humfrz

Hey, let the kid answer for himself.

hmmm...….I thought the kid was being bashful ……. :bellyroll:


humfrz

LOL thanks for the colorful replies :D I drove the car today between classes, and I found that the sound is only present when the clutch is NOT depressed and the car is in neutral. I can make it come on and go away by letting the clutch out or pushing it in. This relieves me a lot that it's probably not something with the engine but is with the clutch or transmission. Let me know what you guys think.

It's sortof a rattle (like knocking) - you can most clearly hear it in the first part of the video where I am pushing in and letting out the clutch - https://photos.app.goo.gl/gAswtVyc4z5sNFpv2

It could be that the clutch fork is dry and it makes that creaking sound.

I would suggest how you can lube it …… but, I don't want to step on ol @Ultramaroon 's toes ……:sigh:


:D



humfrz

think you're putting too much stock into the sounds, I don't hear anything different between clultch in or out, sounds pretty normal to me...if clutch & stick operation feel normal and if nothing is weird when you're WOT then it probably is just the typical clunky gremlin sounds from this MT..personally, I can hear my clutch chatter once in a while when it is cold.

The engine sounds perfectly "normal" as in it sounds just like an old Russian farm tractor.
I really can't hear the difference when you push in the clutch but that is probably just me. If you start to get a squeal when you start it up that goes away when you push the clutch then get the throw out bearing changed. There is a history of them going bad but the noise is obvious.

Thanks for your help guys! The "throwout bearing" makes sense (idk what I'm talking about lol) I know I didn't know these things made crazy sounds like y'all are saying they do. Oh well, I guess I'll just go around staying awake at night wondering what the newest rattle is :cry: Just glad it wasn't something with the engine. When I first heard the sound, I nearly lost it. I will keep tabs on it and post again if it gets really bad.