View Full Version : Need some help with our 1999 Sienna (1MZFE related)

04-21-2015, 04:39 AM
Long story short, we decided to pick up a minivan to use for our stores and then sell our truck. A truck isn't really needed anymore.

Anyway, I picked up a 1999 Sienna XLE.

It ran a little rough when I picked it up and was throwing codes P0300, 304, and once for 306

I picked up new plugs, and that made it run a little better (Old plugs were fouled out, copper and not the correct plug)

So still not cutting the mustard.

I checked resistance on the injectors for cylinders 4 and 6. They were kind of wonky, so I snagged some from a 1998 1MZFE Avalon at the bone yard.

Tonight, I put them in. It fixed the issue! Ran great, no sputtering, etc.

But then I decided to throw on the new plug wires I ordered.

And now the van runs like absolute shit. At first it threw P0300, 303, and 305. Those are codes for the back cylinders by the firewall.

I checked the plug wires, reseated them, and cleared the codes.

Still runs like absolute crap. It sputters, runs rough, idles rough, and will die out if you let it sit in idle. No power, backfiring, etc. The codes didn't come back on even after 20 minutes of running rough and then even several key starts, etc.

The van is a CA emissions van, and the injectors are from a Federal Avalon. I'm not sure if that would have anything to do with it, because it was running just great for about 20 minutes before I decided to change the plug wires.

I'm totally stumped and could seriously use some help with this thing so we can sell the truck and get some use out of this.

I don't know if I fried the coil packs somehow by changing plug wires, or maybe the ECU isn't liking the different injectors.

I'm totally stumped, so if anyone with 1MZFE experience has some help, I'd appreciate it tremendously!

04-21-2015, 08:01 PM
Well...seems to be running fine now. Apparently the plug wires I got from Rock Auto were total crap, and the ones that came on the van had a few splits in them.

We'll see how she does after Safelite comes to do the windshield tomorrow