Tune Up - Toyota Nation Forum : Toyota Car and Truck Forums

dgoodhue · 10-02-2006, 08:00 AM

A month ago, I bought a used 2002 Chevy Prizm with 53K miles. My gas mileage is down a little bit 4-5mpg from what the Window sticker says (I drive the vehicle really easy.)

When is the recommended tune up interval for these vehicles? My air filter is a little dirty so I am going to replace that. Tire air pressures are fine. Should I replace the plugs, wires, fuel filter?

I also have a 02 Toyota Highlander with 54K miles and its gas mileage has been consistent since new, all I have done change the oil and air filter. it recommended spark plug change is 100k.

dgoodhue · 10-06-2006, 09:33 AM

I guess no one does tune ups on the newer vehicles. I will post in this thread if anything seem to make a significant difference.

sportrally88 · 10-06-2006, 01:21 PM

i recogmend tuning up any used vehicle you ever own!!!! asap!!!!! and change all the fluid!!!!!all of the fluids!!!!!!!!asap!!!!!!!!! and drive it hard atleast once just to see if there are any quips or so........check the suspension aswell and change every filter u can find!!!!!!!

bbsgarage · 10-06-2006, 02:05 PM

I think all of the people that know anything here are busy bashing each other over in the oil thread

But even with the poor spelling, most of the above advice is good.
Not sure if there is a throttle body or not, but if so I would clean that out with some good TB cleaner. Injector cleaner might not hurt either.

sportrally88 · 10-06-2006, 07:01 PM

i dont spell that bad and try to give thebest advice i can

Flashmn · 10-07-2006, 09:21 AM

Might be colder temps = more dense air = needs more gas = mileage goes down. I wouldnt bother about 3-4 miles, thats not too bad.

dgoodhue · 10-07-2006, 10:29 AM

Quote:

Originally Posted by Flashmn

Might be colder temps = more dense air = needs more gas = mileage goes down. I wouldnt bother about 3-4 miles, thats not too bad.

Its 4-5mpg and I have a 77 highway mile commute each way. My best has been 35.8 mpg, its been more like 33-34 lately. It been like this when I bought the car when the temps were 80 degree as well (when I got my best gas mileage). Quite frankly if I can't get any better I will sell the car, its just not worth it for me to drive it getting 35 mpg, I would rather have something funner to drive car that gets 30mpg or I will buy a Turbo Desiel VW. I was expecting close to 40mpg, like the EPA rating. My friend hits 41mpg with his everyonce in a while so I know its not aberation.

bbsgarage · 10-09-2006, 09:46 AM

What about traffic? Whenever I get into traffic my milage goes down 2-3 mpg.
My commute is 55 miles one way so I feel your pain.
I was getting 28-30 with my 98 neon but stopping every 2 days for gas was killing me. Now I can go 3-4 days without stopping. My best has been 38mpg, but I do tend to have a heavy foot.

dgoodhue · 10-09-2006, 04:34 PM

I don't hit any traffic, I leave @ 6am and I am out area of traffic by 6:45-7am,so goes or the evening commute.

I added a few psi of air to get my tires up to 33psi. I am going to change my oil, I am not sure what viscosity the dealer used. My new air filter is coming in this week (the other one looks original)

I also wonder if my driving at 75mph is reducing my gas mileage as well. I am going to try to change one thing at a time to pin point it down. I check the plugs, they looked fine and they are the Iriduims, $14/plug

I will try a few things other things first, the manual say 120K miles to change plugs.

toyotaspeed90 · 10-09-2006, 05:42 PM

Quote:

Originally Posted by Flashmn

Might be colder temps = more dense air = needs more gas = mileage goes down. I wouldnt bother about 3-4 miles, thats not too bad.

except that by 2002 the efi setups should be capable of dealing with different temps and atmospheric pressures....

i *personally* would consider changing out your o2 sensor.... they are generally ignored at wide-open throttle (runs rich) and who knows how the previous owner drove the vehicle....

and if you're concerned about better gas mileage.... bump the tire pressure up a bit, get a cotton-based air filter (like a k&n) and change the spark plugs

Flashmn · 10-09-2006, 05:52 PM

Quote:

except that by 2002 the efi setups should be capable of dealing with different temps and atmospheric pressures....

Yes, thats what I'm saying. In colder weather they inject more fuel. Its just physics, you need the 14.7:1 fuel ratio... and to get it in colder weather you need more fuel.
Thats why the engine monitors IAT and MAP readings.

dgoodhue · 10-10-2006, 07:22 AM

Quote:

Originally Posted by Flashmn

In colder weather they inject more fuel. Its just physics, you need the 14.7:1 fuel ratio... and to get it in colder weather you need more fuel.

I personally don't beleive that statement 100% . Yes cold air means a more dense air charge, which mean the engine need more fuel for the same amount of air at higher temperture, but it also means the engine creating more hp. To keep the same constant speed you actually need a less throttle (air). Mathematically (theorectically) the fueling should be very similiar. Cold temps makes oil viscousity higher (it also improve cooling efficiency as well), so friction is higher, so that will reduce gas mileage.

Bitter · 10-10-2006, 12:26 PM

winter blended fuels dont have as much energy per unit of fuel.

dgoodhue · 11-13-2006, 08:00 AM

The only thing I haven't got around to replacing is the O2 sensor. My regular commute which about 60-70% highway was yielding 30 mpg when I first started this. I now have it up around 33mpg. The biggest difference was the tire pressure from 28 to 33psi (about 2mpg) Oil change (I think the dealer had used a higher viscosity oil) seem to make a slight difference. Fuel filter, air filter, spark plugs may have made a difference, but if it they did it was under 0.5 mpg< I ended up doing each individually. If I want better gas mileage I probably need to slow down quite a bit more on the highway portion, most of its a 65 mph zone and I usually drive 75mph. I tried slowing down to 70mph and it netted me less than 1/2 mpg. I probably need to drive 55mph to get 40mpg

I will probably try the O2 sensor (if its not too expensive), then I am going to try another aero trick to attempt increase mas mileage. If either work I report back.

toyotaspeed90 · 11-13-2006, 04:41 PM

well, you won't necessarily gain mpg by going slower......

engines don't necessarily use less fuel when running at a lower rpm.... that's somewhat of a myth.... it all depends on the engines efficiency range....

for example.... in my ae92 (with a smallport 4age) around town (because i'm in high rpm's a lot, o2 gets ignored, etc...) i get around ~25mpg..... at about 70mph i get around 30mpg.... but on some of the long highway stretches (when my g/f lived 200+ miles away) i found out that i was getting nearly 40mpg by doing 90+mpg..... ie, engine efficiency (and actually also the aerodynamics of the car -- at what speed is there less resistance... but i don't see that being much of a factor in a 1990 corolla)