Attempted to diagnose a new ticking sound. I'm now even less sure what it could be.
I recently took off the intake assembly to replace my fuel injectors. I was attempting to reduce or eliminate the occasional engine bog at highway speeds going uphill (4-cyl automatic doesn't have any spare power, but I didn't think flooring it at 60-70mph was supposed to bleed speed that much). I was also looking for signs of what could cause a pulsing hiss on the intake side somewhere, and while I was at it, I replaced my fuel filter and cleaned out the intake ports, throttle body, and everything in between.
During disassembly I noticed the PCV grommet was torn, which I wonder if that may have caused my hissing sound. Regardless, easy enough to replace that grommet and definitely necessary. Fuel filter replacement was the easiest thing ever with the intake assembly removed. The intake ports were very dirty, and I did my best to clean them with valve & carb cleaner and a shop vac to try and get everything out, being especially careful with cylinder #2 which had the valves open on the intake stroke.
I also took the IAC off to clean since the gasket kit I got for the throttle body included one. That may have been a mistake... I partially stripped the head of one of the four screws, but managed to get it fairly clean and reassembled to the throttle body.
Everything went back together fairly well and easy with the exception of the #4 injector cup, that was a bear to get seated. After checking and double checking everything was bolted, torqued, vacuum hoses reattached at the right ports, etc. I started her up. Took around 10 seconds of cranking for the fuel to get through the empty lines and new filter, but it started up fairly well! While looking for any leaks, I only found one connector I had missed, the lower plug on the IAC which I quickly connected. Then as the engine warmed up and the RPM lowered to normal idle, I noticed the ticking.
I'm not an expert at the various causes of engine ticks and how they sound compared to each other, but I can tell it's on the intake side, and seems to be louder towards the back of the engine. I tried disconnecting each injector plug one at a time, but that didn't eliminate the tick. However, when I tried to use a long screwdriver to "listen" to the injectors and the engine block by the intake ports, it seems like the tick IS coming from the injectors.
I was hoping to avoid taking everything apart again to check valve lash, but then I noticed a drip under the throttle body. It looks like the gasket and coolant lines to and from the IAC are all leaking.
The good news is my pulsing hiss has not returned. My guess is that was the PCV grommet. Unless, the pulsing hiss was one or more intake valve not seating fully when closed, and the gunk was sealing up most of the gap. When I cleaned out the gunk, the gap is now open and causing a tick?
There goes my planned camping trip next week.