Toyota Sienna Engine Problems

Replying to: ateixeira (Jul 23, 2007 6:51 am)

Replies to this message:
• ateixeira (Jul 24, 2007 7:20 am)
  • newtovans (Aug 05, 2007 5:30 am)
    • fccn75 (Aug 09, 2007 9:23 am)

Replying to: caravan2 (Jul 24, 2007 4:13 am)

It's fairly well detailed here:
 
http://www.angelfire.com/ky3/gabby/intake_mod.htm
 
The funny thing is that it almost didn't make sense to me. I can understand that freeing up the air intake would reduce hesitation and increase power under certain circumstances, but I didn't believe the improved mileage claim.
 
Thing is, I just can't argue with results. I drove to the beach this weekend and averaged 30.6mpg for the (all highway) trip. Yowsah.
 
That's better than I got doing the same trip in my Miata!
 
And we had 4 people, a dog, a little bit of luggage, and the A/C was on the entire time (DC summers in July are hot/humid).
 
I can't say exactly how much it improved my mileage because I've only had the van for 1700 miles. I did wait to do this until after the 1000 mile break-in.
 
The mod is very, very simple. You disconnect two vacuum hoses and re-route one to another location. I took the additional step of getting caps so that everything was sealed nicely.
 
Does it affect the warrranty? I'll answer "maybe". It's not stock, but it's very easy to reverse and there would be no signs of any mods. Plus, past half throttle the intake operates like this anyway. This just leaves it in that double-intake-path mode all the time. You don't have to wait for the vacuum tubes to operate and suck the 2nd intake path open, hence some people say it hesitates less (note I did not notice any hesitation prior to the change).
 
So this is your call. If you want to try it, note your mileage on a certain trip. Then, take that same trip again after the mod, and see if you notice a difference. The site claims a 1-2mpg improvement. I seem to observe about that much improvement, but again, my engine is green and breaking in, and it might have improved even without this mod.
 
Trade-off? More noise. My wife noticed it once, but we got used to it pretty fast, and I don't want to give up 30+mpg plus quicker throttle response, so to me it was worth it.

Replies to this message:
• newtovans (Aug 05, 2007 5:30 am)
  • fccn75 (Aug 09, 2007 9:23 am)

Replies to this message:
• ateixeira (Jul 27, 2007 8:02 am)
  • siennasweden (Jul 27, 2007 8:24 am)
    • ateixeira (Jul 27, 2007 8:36 am)

Replying to: siennasweden (Jul 27, 2007 4:52 am)

Replies to this message:
• siennasweden (Jul 27, 2007 8:24 am)
  • ateixeira (Jul 27, 2007 8:36 am)

Replying to: ateixeira (Jul 27, 2007 8:02 am)

Replies to this message:
• ateixeira (Jul 27, 2007 8:36 am)

Replying to: siennasweden (Jul 27, 2007 8:24 am)

Replying to: ateixeira (Jul 24, 2007 7:20 am)

Replies to this message:
• fccn75 (Aug 09, 2007 9:23 am)

Replying to: newtovans (Aug 05, 2007 5:30 am)

The SER was a very nice car: '92? 2.0, 140hp for the time was fantasitc!
 
New to this site and glad to have found it after all this time googling on the humming issue with '07 Sienna LE without substantial results.
 
Have 1700 miles and experienced the same exact issues: humming/moaning 2300-2500 rpm under load such as accelerating lightly but not enough to drop to the next lower gear. Especially noticeable on long stretch of inclines. The sound is very accurately described in your post - almost like a resonating exhaust vibration due to a resonate frequency in the narrow range of rpm. Don't know about the rest of the owners, but I find it very annoying when it does hum. Sounds almost as if I modified my exhaust system - and droning!
 
I tend to lean toward the exhaust noise as opposed to the intake noise especially as described the VSV takes on >3200 rpm. Reminds me of my late '85 corolla gts (redlines at 7500rpm) where it would operate the second set of intake valves after 4200 rpm.
 
Needless to say, I brought the van to the dealer for diagnostics and they were unable to find any problems. They informed me that they were unable to duplicate the noise which I had confirmed with one of mech. on a test drive. I guess this means that the noise is normal due to a design issue/flaw and that not too many drivers notice it.
 
I'm glad to find out that there are owners that experience this noise and that this "problem" does exist. Now what to do about this?
 
Wondering perhaps additional isolation engine mounts or something in the exhaust?
 
Anyone knows of TSB regarding this?

Replying to: ateixeira (Jul 16, 2007 7:10 am)

Replies to this message:
• ateixeira (Aug 15, 2007 8:17 am)

Replying to: siennami (Aug 15, 2007 3:06 am)

The 2GR is louder because it uses a timing chain, vs. a timing belt. Chains are noisier and have more reciprocal mass, but they don't have a service interval and are far less likely to break.
 
Toyota compensated by adding extra insulation on the firewall and under the door sills, so while cruising my Sienna is still very quiet.
 
Under full throttle it definitely asserts itself. But I like that.
 
The hesitation may be the two-path intake. There's more information about that (and how to modify the intake if you are so inclined) here:
 
http://www.angelfire.com/ky3/gabby/intake_mod.htm