Last post on Jul 18, 2007 at 10:32 AM
You are in the Toyota Sienna
What is this discussion about?
Toyota Sienna, Van
#2093 of 3687 Ok, so to rebuild....
Aug 09, 2002 (9:37 pm)
Well, its going to take a month and a half to get the 1999 Sludged Sienna (68,000 miles) in for a "rebuild." My Toyota dealer said I was 6th in line for the work.
Anyone have there 3.0 V6 engine rebuilt because of sludge? How did it go? Hows it run? What was the warranty on the rebuild engine? Did they use different parts to help prevent engine sludge from coming back? And if it does, will Toyota cover another "rebuild?"
Love our Sienna, even though its smoking now and then on startup it, runs smooth as silk.
#2094 of 3687 Ongoing fuel "controversey"
Aug 10, 2002 (4:39 am)
RR: We've discussed the octane question before. I used to believe that higher octane was a waste of money. Then I tried it on my '02 Sienna; my gas mileage did increase in a non-scientifically significant way. Try it yourself to reach your own conclusions. Mixing octanes is probably a waste, though... BTW, the Sienna's engine has a compression ratio of 10.4:1...rather high.
As far as high-octane for emissions tests, in our state (CT), the word is to use Mobil Super + (93 octane) to clean your valves a little to pass your test. You can also use some Chevron Techron (which has a Porsche part number!) to clean your injectors and valves.
If I lived where it was available, I'd use Chevron fuels, which contain Techron; here, I use Mobil Super +...
#2095 of 3687 Ongoing fuel "controversey"
Aug 10, 2002 (6:19 am)
I use the high octane fuel in my Sienna here in CT also.
My reasoning is due to the variable timing in the engine (VVT-i). The engine should sense knock and move the cam shafts accordingly (along with spark) to allow the engine to run with the timing advanced. This would allow for more power with less gas. The high octane allows the timing to be advanced without knock longer than regular gas.
Aug 12, 2002 (3:22 am)
Another high octane customer from CT - just following the manuals recommendation.
Not sure of the technical reasons but I get 24 - 25 mpg with it. Usually Gulf 93 octane - with the Fleet Gulf card discount it comes out to be around the same as the mid-level juice.
#2097 of 3687 Going from 87 to 91 Octane - cost (a lot) vs. benefits (not much in most cases)
Aug 12, 2002 (5:14 pm)
Many people are aware in concept of a modern engine's ability to adjust itself based on octane rating and use that as the reason for using higher octane. However, the key questions is - how much difference does it actually make, i.e., what is the range of that adjustability in a given engine? Let's say 91 Octane cost 15-20% more than 87 octane. Unless you gain that much (15-20%, or close to it) in performance/economy by using the higher cost 91 octane, then essentially you're wasting the difference between the extra cost and the performance/economy gain.
% waste = % of extra cost - % of performance/economy gain
In November 2001 issue of Car and Driver, an article titled "Regular or premium" looked at this issue by doing comparison tests on five different vehicles using 87 vs. 91 Octane, plus some good technical explanation on what Octane rating is all about. Below is the web link for the article; the hardcopy has more charts, which are not shown on the web.
Two things to keep in mind when interpreting and relating the results:
1. Performance variability - Even under identical test conditions, the performance of a simply electrical/mechanical device often vary slightly during different test runs, or even during the same test run as the system heats up, which can be observed easily with accurate test instruments. An engine behaves much the same way. If you tests a engine and measured 200 HP and you repeat the test five more times, you should be in the neighborhood of 200 HP, but you may get a slightly higher or lower result (by a few percents) each time. The Honda Accord (V6 with VTEC, probably the one most similar to Sienna's engine in application) tested actually lost a little performance when 91 Octane was used instead of 87 Octane. The Mustang and the Ram gained a little. In each case, the small measured differences could easily be due to the natural performance variability between test runs, rather than the result of the Octane rating change.
2. Test condition vs. normal driving condition - The fairly small performance difference reported in the article is based on the maximum power condition - you floor it and keep it there. The performance difference at "normal" speed that 99% of us drive at 99% of the time would be much smaller still.
Why would a reasonable person want to consistently pay 15-20% more for anything and get not much benefit in return?
San Jose, CA
#2098 of 3687 Using premium gas to pass emission tests.
Aug 12, 2002 (5:41 pm)
This may have more to do with the extra additives they put in the premium gas (which varies from brand to brand) than the Octane rating. As a short term fix, you may be able to do the same thing with a can of those engine treatment solutions they sell in auto parts stores. In any case, it's like taking pain killers when you're sick - you're just masking the symptoms temporarily, but you're not necessarily fixing the root problem.
San Jose, CA
Aug 15, 2002 (4:30 am)
The term "engine knock" have been mentioned quite a bit in this discussion. Is it something that you hear while driving or after you've come to a stop?
#2101 of 3687 railroad17
Aug 15, 2002 (7:55 am)
engine knock/ping can heard usually when you step on the gas (accelerate). depending on how bad it is, it can be heard as well even if
your engine is idling.
Aug 15, 2002 (8:52 am)
I've heard it described as a knock and a ping, but I believe a better description is a rattle. It's kind of like dice being shaken in a bottle.
jeprox is right about it happening at any speed, but my experience is that it usually happens on acceleration. My truck was doing it when I kept a steady 73 MPH also. If I accelerated or took my foot off the gas it went away. (That's because those things change the conditions that cause the ping in the first place.)
Everything I've been able to dig up on pinging has told me that there are several causes, but the damage can be extremely severe. All the sources said to get it taken care of, or suffer major engine damage.
Here are the things I found out:
Improper fuel - octane too low
Ignition timing - Timing set too advanced
Spark plugs - old and/or not properly gapped
Overheating - bad thermostat, ignition timing off, bad water pump, clogged passageway
Wrong oil - Oil viscosity is too low; getting past the rings, burns in the engine, creating deposits
(that was my problem. I put the 5W30 meant for the Sienna into the truck, which should have had 10W40. D'oh!)