00 Sienna Misfiring

Can you reach them from underneath the vehicle!

Dealer.

Gary Eickmeier

Man, dealer nothing!! Way to give up there, Gary!! Anyone with a basic set of hand tools can change freakin spark plugs. It's not like he's changing out an inverter on a Prius for Christ sake! Anyway, pull the pcv hose out of the way and disconnect the 12mm bolt securing a ground strap to the right side of the intake manifold surge tank. Then you can get a 3" extension with a sparkplug socket under the manifold and into the plug tubes. Snake a ratchet in there, and you're good to go. It's a pain in the ass, but it's doable. Post if you need more help. "Dealer"....... sheesh.

Dealer.

Gary Eickmeier

Thanks for the advice. I got the #1 out last night leaving just the #3 plug unchanged. The van is running rough still, but the Autozone computer diag said "multiple engine misfires cylinders 1 and 5. Knowing that I've changed all the plugs so far and still have the prob...wires next? Or coils?

Gary Eickmeier wrote:

You don't have spark plug wires (in the traditional sense). It's either the plugs, coil packs or could even be a faulty fuel injector. What plugs did you use as replacements?

Nirav

You know what, there is a TSB involving coil replacement for the 1MZ-FE in some Camrys and Solaras the display a misfire code. I do not remember if the Sienna is involved. But in the meantime what you can do is switch your coils around and see if the misfire moves with them. Your van should only have coils on the front bank, which are cylinders 2, 4, and 6, with plug wires going from each coil to cylinders 1, 3, and 5. Changing the coild is real easy, just pop the 10mm bolt securing the coil, unplug the connector and pull it out. If you shuffle things around and the same codes persist, you don't have a coil problem. I'll check that TSB tomorrow. I'm curious now.

I changed all the plugs still ruinning rough. Last Autozone diag was cylinder misfires cylinder #3, changed plug, all new now...if cylinder

3 is still bad, gonna change the wires, coil last

Ok, all new plugs, new wires. Running now like its choked, but smoother than before. Check engine light is now blinking. Any ideas?

Are the new plugs and wires OEM or aftermarket? If they are aftermarket, performance will tend to suffer.

aftermarket, but even when I change back to original wires and plugs, still runs the same. Autozone said that the diag tool will read the same problem until there have been 50 starts to clear the computer. Anyway to clear it sooner to get a more accurate reading?

Original, as in what the van had when you bought it? If so, they were probably due for replacement.

To put it another way, get new OEM plugs. The original wires, however, may still be OK.

It had Denso's in it, I replaced them with Bosch...are you suggesting that even though I changed plugs and wires, its still running rough cause of those new plugs? Anything else I should be looking for? I don't think coils are bad.

**Update** Installed all new plugs and wires. Engine check light is still on, blinks at steady higher rpms. Running almost like its choked, but is driveable. Any suggestions where to go next?

Bosch makes good products but people often have problems with their ignition parts in Toyotas. Stick to Denso plugs and ignition parts.

The flashing light, assuming that it is still misfiring, means that the system has detected at least 1 misfire every 200 RPM, with the possibility of catalyst overheating. An overheated cat is a BAD thing because it can ruin the converter or worse, start a fire.

Possible causes are:

The ignition system, including plugs, wires, coils. Install new OEM parts and check to make sure the low voltage wires to the coils are solidly connected.

EGR, injectors, valve clearance, ignition timing are other possible causes.

If the new OEM parts do not resolve the problem, you need to take it to a shop, preferably a Toyota dealer, with a more advanced OBD II diagnostic tool (one that does more than just give trouble codes), an oscilloscope, a factory repair manual, and factory trained technicians.

Can I test the fuel injectors to make sure its not one of them? I will put an ohm meter to the coils tonight.

Yes, you can test the fuel injectors.

You can might be able to feel them fire by laying a hand on them or you can put a meter on it to see if you get a firing pulse.

The only thing a resistance measurement will tell you is if the unit is electrically sound. It will NOT tell you if the pintle shaft is moving NOR will it tell you if the injector tip is clogged (whole or in part).

At this point, I'm thinking its a clogged or failed fuel injector...maybe the #3...I will test the coils first tonight, then maybe add some fuel injector cleaner?