An inexpensive obd2 scanner allowed me to monitor the short and long term fuel trim on my 99. The control box thought the engine was running lean so it was adding fuel trying to compensate. A lot of fuel. Then it was just a matter of figuring out why the control box thought it was running lean. In my case it was a faulty mass air flow meter.

 

An inexpensive obd2 scanner.... a faulty mass air flow meter.

Full disclosure: Prior to scanner purchase, in a failed attempt to correct the poor mileage, I replaced the O2 sensors, cleaned and tested the injectors, looked for intake leaks using smoke. Though not the main cause, engine runs so well, mileage is so good, these tasks were needed anyway.

 

Yeah, you definitely need more data. You can do some preliminary checks like changing the air filter and inspect vacuum lines, but you need to know if it's rich or lean. Then, you narrow down the potential causes and eliminate some things entirely. OR just take it to a trustworthy mechanic and they'll do the same.

 

My trusty mechanic will do the checks next wednesday as I have no electronic knowledge and very limited tools . Odd that the older I get the less strength in my hands , there must be kryptonite around here. Now I will find a how to video on sparkplug changing on the V6 , I hear three of them are a piece of cake ! I will keep you apprised of the findings and hopefully get decent mpg's

 

My trusty mechanic will do the checks next wednesday as I have no electronic knowledge and very limited tools . Odd that the older I get the less strength in my hands

It's not knowledge, tools or strength, it's a question of stingy. I'm too stingy to pay a mechanic $150 for five minutes of scanning. Enjoy solving the mystery and once solved you'll be empowered from then on.
Give a man a fish and you feed him for a day; teach a man to fish and you feed him for a lifetime.

 

I am going to say this. AWD Siennas are not known for making good fuel mileage.... Things that could make a difference. A clean air filter Air filter. Tire pressures also make a difference. I run 45PSI in mine.
Location/ area makes a difference also... Hills ETC.

 

I am going to say this. AWD Siennas are not known for making good fuel mileage.... Things that could make a difference. A clean air filter Air filter. Tire pressures also make a difference. I run 45PSI in mine.
Location/ area makes a difference also... Hills ETC.

Yes I am aware that the awd does not get stellar mileage but when it gets less than advertised and I am not racing around , then something is amiss with the fuel mileage.

 

Good to see I am not the only cheap guy here! My mechanic does not charge for scanning , and his wife enjoys my cookies.
Give a man a fish and you feed him for a day; teach a man to fish and you find a taxation revenue stream.

 

FWIW, scanning is trivial. You don't pay for the 15-minute once-over and scan. You pay for the 15 years of experience it took to get to the point where you trust him to do the scanning.

Also, the secret to getting weaker as you get older is to use a longer pipe on the wrench.

 

It took less than 300 miles in fuel saved to pay for the scanner. Maybe 600 miles for the time learning what the numbers and graphs meant. Next time, or different vehicle, it's free.
Only cure for weakness is use, mental or physical. Fix you car, you'll live longer.

 

That overhead display that tells me what direction I am going and the gas mileage , is bouncing from 78 mpg ( I like that ) and down to 9.9 mpg?
So where is it getting it's information from?

 

Displayed mpg is generally based on wheel speed and injector pulse width over time.

Sixto
‘04 LE FWD

 

So I am doing 60 mph down the highway and the overhead display is constantly changing up to 78 mpg , down to 12 mpg , up again ? No drop in speed just steady .speed and wacko readings. Is this indicative of some sensor going awry? My MPG is about 12.6 when I hit the gas station and check mileage against gallons.

 

If you’re on level terrain with no change in rpm or load then that is strange. It was already suggested to check live data - MAF, fuel trims, throttle position, etc. I have a $15 Bluetooth dongle that works with my phone that shows live data.

Sixto
‘04 LE FWD 203K miles

 

Weird.
OK. So try doing a manual MPG test. Seems you are only going off the data from the vehicle? Might be giving you bad info as it spikes up and down.
Run a tank or two to confirm what the Sienna is actually getting and don't worry about what the data is saying.

 

Seems you are only going off the data from the vehicle?

No:

My MPG is about 12.6 when I hit the gas station and check mileage against gallons.

 

Unfortunately the last three fill ups or shall I say the first three as I have only had this from Nov 03/22 it has been consistent at 12.3 mpg combined city highway with more highway than city. So it is going to my mechanic, to have his far better tools diagnose and fix the mileage problem . I have no history of the van mechanical fixin's and I just saw that the sparkplugs are good for 120000 miles and the odometer says 134000 miles on the van . So just like my 98 Sidekick , things do need changing after a while. On the Sidekick 420000 km was the time when 3500.00 per year replacements started kicking in.

 

So just like my 98 Sidekick , things do need changing after a while. On the Sidekick 420000 km was the time when 3500.00 per year replacements started kicking in.

Your over reacting. My former gas hog cost me $33 to fix. Including a new tire stem, the $35.00 per year replacements started kicking in. $33 scanner not included.

 

I will post here what the Mechanic finds and does to get me better mileage . 420,000 km is 260,000 miles and my odometer says 134,000 so it has a ways to go before major fixing comes into the conversation.

 

FWIW, if the work is done at a mechanic, as it comes up, I would expect somewhere around $4-6k worth of work to be done over the span between 100k and 150k miles. Spark plugs, intake/TB gaskets, timing belt/water pump on the 3.3L or just the water pump on the 3.5L, radiator, front/rear suspension, brake work, O2/A-F sensors, exhaust, trans filter/flush, valve cover gaskets, etc. If you put off some stuff (i.e. suspension, exhaust, etc.) which doesn't particularly prevent you from driving the vehicle, I could see a large bill coming due every 6 months. If you take it to a dealer, that $4-6k would probably transform into $10-12k around here.

 

I also got a 6 month extendable warranty with this beast , however it is for things that break from the inside out . I guess I have to expand my monetary concepts of owning a Toyota or sell it asap and enhance my old 4x4! Thanks for your imput.

 

I guess I have to expand my monetary concepts of owning a Toyota or sell it asap

Says more about mechanics and dealerships than owning a Sienna. I'm feeling sympathetic, how much do you want?

 

The 2009 i have i bought in 2012 with 40,000 on it. It has 123,000 now. I have done nothing major
But have done :
1) changed out the oil cooler hose to an all steel one. The vvt line already is the steel one.
These two things are a potential failure, but its not a chronic problem.
If you have a rubber one of either of these it should be addressed.
2) replaced the radiator recently, its been seeping out of the tank for at least the last 10,000.
3) just changed the spark plugs, and put three new coils in the back.
The is a scheduled event that was supposed to happen at 120,000.
There are some out there that are pushing 200,000 and still have the original plugs.

I have noticed the rear u joints on the driveshaft are a tad crunchy.
I will have to address this soon.
The transfer case has started to seep some, I just check it every oil change.
The steering rack is seeping some. I will have to deal with these soon as well.
Or maybe not, its not a show stopper at the moment.

Other than that its been basic maintenance only.
I think once you pass 125,000 or so with all vehicles various problems will arise.
I would say the engine and trans are solid at least and the odds of either of these failing is very low.

Oh and by the way it would interesting to hear what is causing the awful fuel milage.

 

Alrighty just got the 4 hour walk about in and came back to the mechanics shop to find that the tires were lower than what they should have been ( new Blizzak snow tires and now at 38 psi ), he cleaned the MAF , added injector cleaner , and informed me about running the defrost as that turns the AC on without telling anyone. So everything else checks out , but the thermostat as he said it is opening too soon and not being at the right temperature the engine will be signaling the computer to add gas as it is not warm enough. So Thermostat and temp sensor are going to be replaced in January just after all my stocks go ballistic . Hmmmmmn gotta lay off the hopium pills.

 

added injector cleaner

🤞A cross your fingers move. Personally never found it very helpful. My brother added it to his Chrysler fuel for years til I finally replaced the pissing injector.

 

I think you may need more hopium pills. The van should throw a P0128 if the thermostat was staying open too much.

What ambient temps are we talking about? I think in a previous post I said that I lose three of four mpg in the Winter - from 23mpg Summer down to 19mpg Winter, city/highway - but Winter temps in parts of Canada can be very different from Winter temps in Colorado. Are you talking about consistent <10° F / -12°C?

 

What ambient temps are we talking about? I think in a previous post I said that I lose three of four mpg in the Winter - from 23mpg Summer down to 19mpg Winter, city/highway - but Winter temps in parts of Canada can be very different from Winter temps in Colorado. Are you talking about consistent <10° F / -12°C?

Up to now the last month of my ownership ( Nov 02/20 to now ) I have gotten 12.1 mpg so somewhat less than what you get on a bad day. If you saw the carnage in Vancouver with an inch or two of snow on the ground and the temperature dipping to -4° C You too could imagine what a real snow fall / drop in temperature would do to us.
The thermostat according to the nice computer screen display shows him ,not me , that the thermostat is not working as it should and highway temperature is lower than it should be . So in January that will be rectified as well. OTOH happy that everything else is up to correct values.

 

Hard to find or get good mileage figures going into the winter. As you can see. I am also from Canada. Will the thermostat help. Maybe. May also help with heat to the interior. They always take time to get good heat inside the interior.

Keep us updated.

 

OK. When my van threw a P0128 I noticed that the dash temp gauge was sitting at the 4 o'clock position during extended highway driving at 80mph and 40°F ambient. A new T-stat had the gauge back at its normal 3 o'clock; and no more P0128.

 

Seems that the more expensive injector cleaner does a better job than the corner store injector cleaner? The Sidekick also got the more expensive stuff and ran better so I will see what happens.
80 mph? Top speed up here is 120kmh /74.5 mph and I am the guy who travels in the slow lane at 55-60 mph pushing less air out of the way. Now I have to wait for 2-3 weeks to take it out for a drive at highway speeds due to a minimal dusting of snow and ludicrous drivers who are just a danger to be around .

 

80 mph? Top speed up here is 120kmh /74.5 mph and I am the guy who travels in the slow lane at 55-60 mph pushing less air out of the way. Now I have to wait for 2-3 weeks to take it out for a drive at highway speeds due to a minimal dusting of snow and ludicrous drivers who are just a danger to be around .

75 MPH briefly, yeah. A short stretch of road (about a mile) that had a speed limit of 70 MPH, and I usually do 5 MPH over.

Except when we went camping in Ontario. Speed limit was 100 kph the entire way on highway 61 from the border crossing in NE Minnisota up through Thunder Bay, even though it was a well maintained 4 lane divided highway. I didn't want to get a speeding ticket in Canada so I was towing our camper at 100 kph, and all the Canadians were flying by me in the left lane. The slowest Canadian I saw was probably doing 120 kph. 🤣 Never did see any cops but did have to slow down for a bear crossing the road at one point on the way back to the US.

BTW, easiest border crossing ever. My first and only land border crossing. I've been to Mexico and three Caribbean Islands by plane for vacation. Pull up on a Thursday to go into Canada with our 24' hardside travel trailer. It's raining and nobody is in front of us at the border crossing. The border agent asked for our passports, which we had ready. Asked which state we were from (they have a mirror, but my license plate was partially blocked on the state because of that stupid dealer plate frame I hadn't taken off yet). She then asked if we had any guns, stun guns, tasers, etc (you guys must think we are gun nuts over here ), asked where we were going and how long (Kakabaka Falls and Sleeping Giant Provincial Park), then handed back the passports and said enjoy your trip. Total time, about 1.5 minutes. I'm here used to waiting an hour or more at tropical tourist traps in airports, so this was fantastic!

She was friendly, the US border guards on the other hand came off with a dickish attitude. Pull up on Saturday to go back into the US, only a couple cars in front of us (but now tons of people with boats heading into Canada, so glad we headed up on a Thursday and came down Saturday). As we pull up, a second border agent steps across the road in front of us to stand on the passenger side front of the vehicle, like he's preparing to search our camper or something. The border agent on my side in the booth asks with an aggressive, almost mean voice "Where did you go? How long were you there? Where do you live? Why did you go to Canada? Did you buy anything there?" I replied "some toilet paper, bread, and beer." It was several minutes of questions, very aggressive, way longer than going into Canada and I'm a US citizen returning to the US! I can't imagine how some or most non-US citizens get treated trying to enter the US. I feel like (and I think I've read) the US Border agents are trained to act aggressively to try to get people to let known anything they may be trying to do that's not honest, but I'm not certain how effective it is. It's really annoying though. This trend of friendly vs aggressive held, in general, for the majority of the US and non-US border agents who have questioned me on my trips to and from Mexico and the Caribbean too.

 

There did not seem to be an answer as to how to get decent mileage above 12.1 mpg my new to me van gets in combined city highway driving.

Out of curiosity is this from the computer? If so, when was the last time the average mileage calculation was reset? Have you reset it yourself since you bought the van? I'm not sure about the 2nd gen, but average MPG displays are not usually a rolling average of the last x miles, but often tied either to a trip computer and reset when you reset the trip computer, or have a manual reset. On my 3rd gen I have a manual reset for my average MPG calculation.

Have you calculated MPG manually by using amount you fill up and miles on that tank? Do you do a lot of idling?

That overhead display that tells me what direction I am going and the gas mileage , is bouncing from 78 mpg ( I like that ) and down to 9.9 mpg?
So where is it getting it's information from?

Is this on perfectly flat surface, cruise control on, steady winds? I watched my instant MPG gauge on my 2014 yesterday while driving down the beltline at ~60 MPH, manual speed control, and just a slight let-off of my foot to slow down very gently because I was approaching a car ahead of me would cause the fuel gauge to jump up to 90 MPG (highest it displays), and adding a bit more gas than normal would cause it to drop to 10 MPG.

As it's instant MPG calculation, large variations are normal with normal driving.

Now I will find a how to video on sparkplug changing on the V6 , I hear three of them are a piece of cake !

If it's useful, I just made a picture How-To Guide on the sparkplugs on my 2014 which has the 2GR-FE engine. I understand the 2008 has the 2GR-FE engine too, but there's going to be a number of changes on the stuff you need to remove to get the spark plugs on a 2nd gen. Still, it may be useful to some extent. I imagine the general process is probably going to be the same on a 2nd gen, just the specifics that will be different (until you get to the plugs themselves). 2GR-FE Spark Plugs - A How-To Picture Guide (2014 LE)

 

My buddies and I crossed at International Falls some 45 years ago. We were all about 18 years old and we all had shotguns. We had zero problems going into Canada or coming back to the US. Has Canada become nutty about guns since then? 😀

 

Our Liberal government is the entity that is nuts and not doing what is correct in gun control. Sort of like going after the mechanic who fixes the car after the driver runs it into the ground and complains .

 

My nice mechanic has informed me that all the other electronic doodads are functioning normally , inflated the tires to 38 psi , cleaned the MAF and put in the high priced injector cleaner ( cleans the wallet at same time ) and sparkplugs are in good shape as well. So I still have a ways to go in running the injector cleaner through in one tank. The mileage that I see on the computer is never taken as truth so I calculate what I put in against the odometer reading. So the only item that he has suggested to be changed is the thermostat as it is opening before correct operating temperature is reached and running the engine with coolant at 167° instead of the 195°+ it is supposed to be . that is set up for fixin in January .

 

Did he say it was running at 167 °F, or did you pull that number from my earlier post?

 

So you are not to bring a gun into Canada for the express purpose of shooting the Sienna for failure to be easy to work on?
notice the clever bend back to what the thread is actually about!

 

Ahhh you are correct I must have pulled it from your post. However the thermostat is opening before the correct temperature and staying open instead of doing what it is designed to do.
It and the temp sensor will be replaced.

 

Ahhh you are correct I must have pulled it from your post. However the thermostat is opening before the correct temperature and staying open instead of doing what it is designed to do.
It and the temp sensor will be replaced.

For about $15, you can get a little bluetooth OBD reader and an app on your phone which will tell you the actual temp of the coolant.