2001 Toyota Sienna misfiring

I have a 2001 Toyota sienna that is coming up w/several misfiring codes. The first time we had it read it had misfiring codes of p300, 301, & 302. We changed the spark plugs. It still wasn't working right so we changed one coil, and had it read again. Now it comes up w/ 300, 301, 302, and 306. The check engine light goes between on and blinking on and off. Do you think this is just a coil problem and I need to replace more coils. Am I reading the manual wrong for which ones to change. We changed the front one to the left if looking at the engine from the front of the vehicle. I though I read that to be 2.

 

One thing you can try on a multi-coil setup is to switch the coil positions; if the misfire moves to another cylinder you've found the culprit.

I'm guessing it's running really bad now?

Plug wires would be a possibility, but it would be a little unusual for 2 or 3 to suddenly decide to go bad. The old ones can be checked with an ohmeter if you have one. How did the old plugs look when you pulled them, especially the ones with the misfire codes?

How many miles on the vehicle?

1-3-5 on the back; 2-4-6 on the front, I THINK.

0300 is "random" and 0301, 0302, and 0306 are cylinders 1, 2, & 6 as you've already figured out. The steady CEL is advisory, i.e. "Excuse me, there's a little problem going on". Flashing CEL means, "HEY, we got a PROBLEM here". I suspect this could be something that's going to require someone with a good scanner to diagnose.

There are a number of other things that could be at the root of the problem such as loss of compression, vacuum leaks, EGR problems, or fuel delivery problems (injectors, fuel pump, etc).

 

It's not running really bad, but definitely rough. The wires don't look bad at all, but apparently are hard to come by. Looks like I have to go to a Toyota dealer to get them. They aren't the old style I remember.
Also, I forgot to mention that we have been having a problem off and on with major smoke (not really blue, darker) just after starting that goes away shortly afterwards.

 

Sounds like maybe you have an injector problem going on there; the dark smoke could be a faulty injector causing an overly rich mixture. That's SUPPOSED to happen to a certain extent on start up (slightly richer mixture to get started; the fuel injection version of a choke), but you shouldn't get a noticeable cloud of smoke.

Plug wires are available; unless you like spending more money I would not buy from the dealer. Found them for $55 (NAPA), also $40-60 for Bosch or NGK at a variety of websites on line. I notice on some of the listings it refers to only using three plug wires because the other three are direct coil connections. Is that your setup?

 

No that's not the right setup. I had found them online at Napa and I think Autozone, but they aren't the correct ones. My son actually went and bought the ones from Napa and had to return them. They don't actually show them in the Haynes book, but it looks like they have a little plug adapter that goes into the coil. The guy at Autozone told me it has to do with it being a distributor less motor.

Are injectors hard to replace? Is it time to give up the fight of doing it ourselves? I like to save money when I can, but sometimes with the newer vehicles it just doesn't seem possible.