Wassup guys,

I have this weird shaking/boom type noise happening to my 2013 GS350 after sitting for a few days. Car is only driven during nice weather so sometimes it sits for a few days. 103k on the clock. What happens is I go to start the car, and during the first 15 seconds or so I'm feeling/hearing this loud shaking like something has been leaking down into the cylinder wall. It goes away after that and won't return again until the car sits for another few days. This isn't the normal startup rattle we all have. It doesn't feel like a misfire, it just feels like someone is lighting off fireworks in the distance and you feel the popping associated. I work as a maintenance tech at a shop, and the senior techs said a leaking injector is a possibility; diagnosing is a pain, and I should let it get worse. I have no coolant loss, so I eliminated this as anything to do the the head. However, after letting the car sit ALL winter, I didn't hear/feel the noise when starting it. Fuel dries out in the lines after months, so this is making me think more about the fuel system. When I first bought the car I did a bunch of maintenance work on it, but the noise wasn't there until recently.

-Plugs
-PCV
-Tranny fluid + filter
-MAF
-Coolant Temp Sensor
-Upstream A/F Ratios (not downstream)
-Coils
-BG GDI cleaning

We pulled the plugs since I swore this all started after changing them- but they looked really good.

I'm trying to debate whether this is normal, I have a stuck open injector, or something else going on. Hooking up the scan tool revealed no misfires, no codes whatsoever. Previous maintenance on carfax/lexus looked really good, everything done on time. Can anyone provide any insight to whether or not they experience this on the FSE or what their opinions are? Do the direct injectors get gummed up in these engines?

 

Pull the plugs after a few days sitting and see if the piston tops are wet?

I haven't looked into it, but maybe live data on a decent scanner will show a misfire on startup.

 

I'll have to borrow a scan tool from work, but pulling the plugs also isn't a bad idea. Might be more worthwhile to wait until it gets worse. I'm trying out some Lucas to see if it helps at all. Anyone else experience this??