2002 XLS poor gas mileage help?

[joebob452]

I came from a 96 Corolla that I had for 12 years got 28 city/31 hwy(80 mph avg) with 300k on it on the same gas (87 octane 10% ethenol) w/ AC on most of the time. Got rear ended a couple of months ago and his insurance totaled it out.
I bought a 2002 Avalon XLS w/115k miles. I tested the gas mileage manually using the fill, drive and fill method.

When I first got the car it got 18.8 MPG on 87 octane, combo city/hwy driving. I changed the timing belt and plugs. The PCV valve was gunked up, so I cleaned it out and made sure it worked (only allowed air through one way). Air filter is good. No check engine light on. Also changed the oil with cheap 5w 30 supertec from wal-mart. The same oil manufacturer (supertec 10w 30) worked fine in my Corolla over all those years since I bought it w/ 20k on it. I also put 4 new tires on it. 35 psi. I live in PA and it is mostly flat.

After the timing belt the car still runs great. But after I checked the MPG on mostly city driving it got only 16.65 MPG on 87 octane! I've also made a couple of approx 200 mile trips mostly all freeway going between 75-85 MPH, no lead foot on acceleration, and got 21.6 on the first and 21.83 on the second.

I'm wondering what's wrong? Edmunds says I should be getting 27 hwy. The edmund's reviews all rate the 2002 Avalon a 9-10 on gas mileage.

I thought I'd get people's opinions before I went on a mad hatter faulty component search. The car runs so good, there is nothing obvious I can think of. Could it be a sludge build up problem? Any opinions would be welcome.

thanks,

Joe

[ChiTDI]

Might be the sludge, I'd change the fuel filter, trans/dif fluid and check again. You are in winter, and the fuel blend may hit the mileage a bit.
My '02 goes twenty mpg all around and about 26 hiway for a point of reference with 110k.

[TrailDust]

Could be any number of issues. My 2002 (41,000 miles...admittedly much lower miles than yours) gets an average of 20 city and 32 highway (at 65 MPH). Overall, I average 23 MPG per tank with the split being 80% city and 20% highway. I use premium fuel at 91 octane, but in California it typically contains at least 10% ethanol. Given the high mileage of your Avalon it could be anything from clogged injectors to low compression causing poor mileage. At this point in the life of your vehicle I don't know that the cost of repair would outweigh the improvement in mileage.

TrailDust

[joebob452]

Thanks for the input.

I don't think it is low compression because it has a lot of power using regular gas. (feels like I'm driving an 8 cylinder). I think if it had clogged injectors it would also not be running as nice.

ChiDTI is the mpg your getting using regular 87 octane gas?

I'm going to try premium next to see if the difference is worth the 15-20 cent per gallon increase in price.

Joe

[tr7driver]

I'm not sure when they changed the engine in the avy, so this may or may not be helpful. We have the 00 avy with the 3.0 engine and 119K miles. With 87 Octane I get 24 in town and about 30 mpg on the highway at 65 mph (using the fill/drive/fill method).

The mpg meter on the car consistently shows about 1 mpg more than the fill/drive method, city or highway. I wonder hou this compares with others that have computed mpg this way. I'm sure my highlander meter is much less accurate.

[silverxls]

i get 22 city and 30 hiway with 87 octane gas also. injectors could be dirty and it still run ok. put a can of PB products 44K in it to clean the fuel system real good.

[joebob452]

My 2002 also has an 3.0 liter in it. It's about what I figured, I'm probably getting 5 mpg less than I should. I'm trying a tank of premium and I'll also try the PB injector cleaner. What does the 44k refer too? When I googled PB Fuel injector cleaner I found Blaster's fuel injector cleaner, but no mention of 44k.

thanks for the help

[silverxls]

man, i'm sorry.....senior moment i guess.... it's BG Products. google BG44k . lol...as i type this i look up and there's an ad for it right here....

[joebob452]

I found it. It's called BG 44K Power Enhancer. They don't sell it in auto parts stores. I had to go to the Cadilac dealer to get it. It comes in a bottle or a can 11oz for both. The dealer only had the can shrinked wrapped with a spray cleaner for the throttle body together for $30. If it works it will be strange since you can't buy it in the regular stores. I'm about to use it soon and will post any improvements in my gas mileage here.

thanks

[ChiTDI]

Originally Posted by joebob452

Thanks for the input.

I don't think it is low compression because it has a lot of power using regular gas. (feels like I'm driving an 8 cylinder). I think if it had clogged injectors it would also not be running as nice.

ChiDTI is the mpg your getting using regular 87 octane gas?

I'm going to try premium next to see if the difference is worth the 15-20 cent per gallon increase in price.

Joe

Sorry for the delay. Yes, 87 Octane BP. I do use an additive regularly for cleaning and lubing the injection system. Fuel Power Plus from LCD Inc.
No, I don't sell it.

[csaxon]

You're at the mileage where the A/F sensors start to lose efficiency which effects gas mileage also.

[joebob452]

I used the treatment in the tank two times. I noticed an improvement the first time, so I tried a second can. I threw away the TB cleaners that came shrink wrapped with it. I just used the fuel tank treatment.

Now it is getting 25 - 26mpg, on regular 87 octane (10% ethenol) with the ac on most of the time with almost all hwy (avg 80mph on mostly flat terrane).

Mostly city it goes down to 19-20.

I'm using no special fuel treatments now and it has been several tanks later and still is getting these numbers which is about 4mpg than it got before. So I'd say that it was worth the money.

thanks for the advice,

Joe

[aznstylez]

did you check your timing after replacing the timing belt? have you given it a tune-up: spark plugs etc...just wondering?

[joebob452]

I made my own marks before I took the belt off. (very important to take the slack out first if you are going to make your own marks). The car drove like normal after the computer reset (disconnected the battery) so I didn't check the timming. I did replace the plugs w/ the recommended iridium from the dealer.

[Tsunami07]

I recently purchased a MINT condition 2000 from some "Leisure-World folks" ...
I put in a K & N air filter, changed plugs and always use at least 89 octane.
Mine has 170,000 .... on a trip to Savannah, got 28.4. highway.

You get better mileage with higher octane, and better performance. It makes no sense (pardon the pun) to put in cheap gas. Your Avalon is permium car, treat it like one!