Done!!!!
Wow, total learning experience for me as a very, very amateur wrencher. To date, the only things I've undertaken on a car were the following: Radiator replacement (01 4Runner, 05 Sienna, and 06 Altima), spark plugs (98 4Runner and 01 4Runner), and alternator (06 Altima).
A bit of the history on this project. My buddy's 01 4Runner was throwing a CEL over a year ago. I ran the code, saw a p0303 and, upon checking the plug found that it was pretty blown. We changed all of them out and the code was gone. No biggie.
Fast forward to December. His 4Runner throws a code again and the engine is misfiring. The worst misfire comes at around 50MPH when traveling up hill. According to the scanner, it's a p0303 again. So, over the phone, I tell him to check 2 things: see if the plug is blown again, and make sure the coil pack is good by switching it to #1 and seeing if the code switches along with it. He tells me he's still getting a code, leading me to think it might be the wires (original, because he's cheap and didn't want to spend the $30 on a new set) or possibly a fouled fuel injector. Since a re-man injector is only about $35 and everything needed to do the job clocks in at about $65 total, we decide to give it a whirl. I mean, why not?
At first, I was a little nervous about the whole idea of taking the plenum apart. Fortunately, I can confirm: YOU DO NOT NEED TO TAKE THE PLENUM OFF TO ACCESS THE 1, 3, AND 5 INJECTORS!!! All you need to do is remove the throttle body. That means you don't need to replace the manifold gasket (top or bottom) at about $20, instead you only need to replace the throttle body gasket (and at 160k, it was advisable) for about $5. Yes, it's a bit tight working in there, but I can't imagine gaining enough real estate by removing the plenum to make the time spent on that worth it.
I did have some issues with getting replacement banjo gaskets for the fuel rail. Went to the local dealership and they had none and all the other ones in the nearby suburbs were out of them. Went to Napa, but the only similar gaskets they carried were SAE and I needed metric. Usually, I curse the fact that I'm a poor guy living in a high-income bracket neighborhood, but then I remember there's a Lexus dealership 1/4 mile from my house. We head over there and relieve them of their last 3 gaskets. Yes, ideally we should have had 4, but you do what you can under the time crunch. I need to remember to use the Lexus dealership more often for Toyota stuff. Getting to the Toyota dealership is a 20 minute trip, so this is a no-brainer, even if it costs a little bit more.
Working slowly, we get the injector rail out and replace #3. As long as you're careful and methodical, it's not difficult at all. I also convinced my buddy that it was worth it to clean the throttle body as there's a good amount of buildup on it. We get it all put back together and torqued to specs and fire it up. At first, there's an issue with the throttle not engaging. Turns out, I tightened the cable a bit too much. After loosening it a touch, it's working great. Success!
Then, we hit the road. And the code returns. Dangit!!!!!!!! We head back to my garage, recheck everything. As cheap insurance, we buy a new spark plug and install it in the #3 cylinder. Nope, nothing. I'm trying to figure it out, and I ask my buddy again, "You're sure the code didn't switch when you moved the coil pack?" And he drops this bomb on me: "Uh, I never did that. I just assumed the whole time it was the fuel injector. It was the only thing that seemed to make sense."
Needless to say, it took 10 minutes to switch the coil pack over and sure enough, that was it. Ordered a new OEM one off of Amazon for $60 and free 2-day delivery. It arrived yesterday and 10 minutes later, it's code free and running better than it has in years. He couldn't believe how well it handled and the better throttle response that came from cleaning and tightening it. He thought he was going to have to get rid of it in the near future, but I just don't understand that thinking. An 01 4Runner with 160k is not something to get rid of, especially with new car payments around $400. For about $120 total and an afternoon in the garage, we got it running again. We could do that 3 times and still be ahead of 1 new car payment.
TLDR: Replacing fuel injectors 1, 3, and 5 is not difficult, if you take your time. You don't have to remove the plenum to get to them. But, you do need to make sure your buddy isn't an idiot and actually checks the simple stuff before undertaking the whole project. Oh, and don't forget to check Lexus shops for basic maintenance items if your Toyota dealership doesn't have them in stock.
