OK, so go to change the plugs. Ugh, don't have a 14mm plug socket, but I can at least get the coils out until I do. BZZZT. How do these bloody things come out? Is there a trick to it? I removed the baffle/insulation that's right above them, and the connectors, but the boots/coils/w'ever are hitting the sheet metal and will not come out. All 4. At least it feels like its sheet metal and part of the car, not removable... am I wrong? help! many thanks! aha, perusing a bunch more threads and doing a bunch more related searches turned this up... didn't realize this video was what I was looking for. apologies if this is needless duplication, mods delete as necessary... but yeah, that's gotta come off. smh
I'm guessing the issue is similar to the regular 3rd gen Prius: you may have to remove the bottom of windshield trim, wipers, wiper motors and the metal cowl (what you refer to as "sheet metal" in your intial post. Yeah, I know, just nuts. @NutzAboutBolts has a very nice video on this, pinned in the 3rd gen maintenance forum. Hopefully it's similar enough to be helpful. If I didn't lose count, it's the 13th one down, here: Nutz About Bolts Prius Maintenance Videos | PriusChat
Yup that was it.... New plugs and coils didn't fix my problem though. ICE startup knocking/misfire. It went away for about an hour but started right back up again.. back to the drawing board
Have you cleaned the throttle body and MAF sensor? There are lots of helpful directions and videos available by searching.
I haven't seen those as a possible cause yet, but I will give that a shot. Going to pick up an inspection camera and look for signs of blown head gasket just in case (I should get one anyway!), but I'd rather anything besides that fix first. :/
I made the spark plug socket by removing the rubber insert from a spark plug socket, cutting it in half, and inserting it in the correct-sized deep socket (I think it's an Imperial, non-metric size you need. Weird). I've heard that the reason for the rubber insert is to keep the ceramic from cracking. Which may be possible, if you're a nincompoop. In my experience, the rubber insert does two things: It holds the plug when you insert it into the spark plug cylinder, so it doesn't fall in, and it holds it when you remove the plug, so you don't need pliers. If the insert holds the plug too tightly, the socket will get stuck in the ignition cool shaft. What you should do is test your spark plug socket by attaching the extension(s) you will use to it, then fully insert the spark plug into the socket. Hold the very end of the extension and pull the plug out of the socket. If the plug comes out, good. But if the extension separates from the socket, the rubber insert is too tight. Don't use it until you fix it by pressing it further in or cutting it down a little. Are you losing oil? Because a blown head gasket will likely leak oil. Before looking for the head gasket, there are some steps you can follow: 1) If you or a friend has Techstream, check for diagnostic fault codes. If you have an old Windows laptop, consider buying one of these babies. About $20 on eBay. There are a ton of vendors selling them. 2) On the intake side, Prius has an EGR valve which vents exhaust gas into the intake. It can become clogged. This is a royal pain because the problem can be the EGR valve (expensive), the pipe between the EGR and the intake manifold, or the intake manifold/throttle body itself. Here is a video of the EGR pipe cleaning procedure. It is very simple. If there is clogging in the EGR, then the pipe will probably look pretty bad. Mine just had a light coating of caked-on crud, which I brushed out, but it wasn't slimy nor was the pipe remotely obstructed. Toyota has a recall on rough startup caused by faulty EGR valve. No mileage limit until next March. warranty enhancement; P0401 EGR Valve | PriusChat Maybe that applies to your car?
Welp, after new plugs and coils it started knocking on startup again after about an hour. I finally let it warm up nice and hot in inspection mode and shut it down, heard a hissing sound from inside the engine, pulled #1 plug (where the misfire codes were coming from) looked inside and found a nice bubbly froth. Head gasket time. It had started using oil, but I figured that was just due to mileage (140k). Coolant was low but not critical. No signs of coolant/oil mixing. film at 11.
Nope, pretty much out of the blue. It never overheated that I'm aware of (wife's daily driver) so I'm left to assume it just "happened." It did happen a couple of one-off random times way previously, but never stayed, we figured out those had to have been lack-of-warmup/condensation flukes. No oil/coolant mixing, no smoke, no noise..... Statistically speaking, it happens. Was hoping to get more than 140k out of it, though. The worst part of this is finding someone that isn't a dealer (waiting to put you over the barrel) who isn't literally afraid to work on it, or who didn't believe me... Because I ain't got time fo that. Found a reputable shop who wasn't afraid of it and they've had it nearly a week with no news (is good news?) .... Not sure if we'll keep it after this, just because of the chance it'll start knocking down the line. May last another ten years, or a month, who knows. It's been a bulletproof little car until now.
Any indy shop that works on Toyota's can do the work. Replacing a head gasket on a Prius isn't particularly different than replacing one on any other Toyota.
@OKPriusV, are you out of the powertrain warranty? FWIW, I've heard head gasket replacement is so costly it's more practical to swap the engine. Also: you're in the States? And maybe id what state?
Did you have the new intake installed.? Did you have some minor start up knock. Or the longer knocking.
