high idle and poor gas mileage

[redtigerrocks]

is the o2 sensor the problem? once in a while when i start it will idle between 1500-2000 but after warm it stablizes. and its only giving around 17 16ish MPG in City with A/C and i need alot more because ill be taking this to college soon . 1994 XLE V6 . and is it easy to install and O2 Sensor? Anyone got a diagram/instruction?

[Stillrunning]

I doubt the O2 sensor is in play at start-up. It hasn't had time to heat up and the engine is in open loop. Have you checked your engine coolant temp sensor or even your operating temp? Where does the temp gauge sit when running? A faulty temp sensor will fool the engine into thinking the temp is lower than it should be so you may be operating with a too rich fuel mixture. A too high idle could also be the IAC valve circuit. A number of other problems can lead to low fuel mileage. How many miles on car?

[-=]KaiN[=-]

on cold start the engine is suppose to fast idle until coolant temp reaches a certain point. As long as you idle around 800rpm at normal operating temp don't sweat the high cold start idle. As far as gas mileage that could be a number of things. Is the cel on? My wifes camry v6 gets 28mpg highway.

[jsl222]

It's probably nothing to do with the coolant seeing that I have similar problems also. I just replaced my coolant less than 200mi ago. When was your last tune-up? Fuel Filter, spark plugs/wires and distributor could be a few factors I think. I also get very poor gas mileage and think it's the O2 sensor.

[-=]KaiN[=-]

Originally Posted by jsl222

It's probably nothing to do with the coolant seeing that I have similar problems also. I just replaced my coolant less than 200mi ago. When was your last tune-up? Fuel Filter, spark plugs/wires and distributor could be a few factors I think. I also get very poor gas mileage and think it's the O2 sensor.

i was just stating that all toyotas go into fast idle on cold start, depending on the outside air temperature= the higher rpm, once the coolant warms up the idle returns to normal. Coolant doesn't have anything to do with gas mileage, but everytime i've seen an o2 sensor effect mileage the check engine light was on. There are lots of factors in gas mileage, ignition parts, carbon build up on the valves, and various other things. If your check engine light is on start there, then move on to the basics, but i wouldn't recommend replacing expensive electrical parts without any indication that they are malfunctioning.

[redtigerrocks]

yeah like today i started my car after a period of 5 days of not driving it and the rpm was high idling but after it warmed up a bit it idled normal. i suspect its o2 as usual. but i also have another question
i do get my check engine light off and on whenever i go around 50 mph on bumps,ditches,etc and whenever i tap the plastic bezel in front of my check engine light/odometer it goes off. Weird huh?

[ekopel]

lol, hey kain, another question actually, im getting poor mileage also, no codes came up on the toyota, lexus, scion scanner tools we use...the only thing i could think of that i could have fucked up is the gap on the spark plugs...if its off though, its off by very little anyway, what flushes would you recommend doing (like the injector cleaner for example, or anything to clean off carbon deposits)

[-=]KaiN[=-]

Originally Posted by ekopel

lol, hey kain, another question actually, im getting poor mileage also, no codes came up on the toyota, lexus, scion scanner tools we use...the only thing i could think of that i could have fucked up is the gap on the spark plugs...if its off though, its off by very little anyway, what flushes would you recommend doing (like the injector cleaner for example, or anything to clean off carbon deposits)

As far as carbon BG makes a good flush kit, has an injector flush, a top end and throttle body fogger, and a tank additive, that could help you a little. What plugs are you running? OE plugs don't need gap adjustments. Have you checked what your fuel trim long term and short term are? You could have a problem you don't know about, but that your ecm is adjusting for, but its not out of threshold for any trouble codes to be set. Is your Camry a 1mz or a 5s, and what kind of mileage are you actually getting anyway?

[ekopel]

1mz, and im in the process of testing heavy vs light foot...it looks like im going to get about 80-100 miles more on this tank...so i think it should be fine...and im running NGK Race Platinums (werent cheap) and properly gapped...

[-=]KaiN[=-]

right on then a 1mz usually gets anywhere from 24-29 mpg highway. My wifes stock 1mz gets like 28-29, and my supercharged 1mz still gets like 23-24 when i keep my foot out of it. If your around that range your probably fine.

[ekopel]

it looks like ill be around 20-24...