Posting this for a friend of my Dads in Michigan... This issue is way over my head and I told him you guys may be able to help... Please take a look! My RS is making a scary sounding noise and I'm looking for suggestions of what I could check. The noise sounds kind of like knock to me, but a little lower in pitch. It's loud and occurrs between about 2000 and 4500 rpm, but only with slightly open throttle. The noise goes away with more than about 1/4 throttle or no throttle. At idle there is also a slight dieseling sound. Here's the story so far: I bought a 2000 RS sedan from a guy who replaced the original engine with a used SOHC, replaced the clutch timing belt, and water pump, and got it running (mostly), but didn't get a lot of smaller parts put back in. I've replaced the stuff that's missing except the intake tubing (which is in the mail). It's had a few problems that I've been working through: Overheating -> flushed a bunch of crap out of the radiator and coolant passages, seems ok now. Misfire on cyl 4 -> replaced ignition coil, spark plugs, & plug wires. checked injectors and ECU per service manual, no improvement Compression on 2 & 4 low -> exhaust valve lash was way too tight. I reset it to spec. Compression back within 5% of 1 & 3. This also cured the misfire. Trans dropping chunks when I changed the fluid -> replaced trans with a used one this weekend. Also replaced worn out thrust bearing & shifter bushings to fix the noisy clutch actuation and sloppy shifter. Replaced motor mounts and trans mount with new wrx mounts. Which leaves the two problems that remain... P1133 O2 sensor heater (low) The Noise I suspected rod knock or a loose flywheel, but I've tried unplugging each injector while it's idling and that has no effect on the dieseling sound. Whether the clutch is engaged or not doesn't make a difference either. I'm trying to borrow a camera with decent sound so I can post a video. Sorry if this it rambly. Any suggestions would be appreciated. Thanks
"Mechanic in a can" should be outlawed, which sounds like he was screwed with. Might start with pulling the oilpan and checking the rod ends for play and pull the rod-ends one by one and look at the bearing surface. Easiest thing to do with out pulling the engine out but sounds like you'll be pulling it soon enough. Good luck
^^ Thanks for your input Breel.. I've forwarded your suggestion to the guy... Sucks more of our members here don't have any ideas.. I talked this site up, assuming I would get more help than this...