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Discussion Starter #1
ok this is gonna be long but i need people to listen and give their most best advice possible........


i filled my tank up two days ago with premium gas (93) and today i have a lil more than half a tank left and i've only gone 83 miles. i dont turn my A/C up to more than 3 and i dont think im burning the gas because there is no black smoke coming out the back of my exhaust. I called the dealer and asked them what the deal was and they said a few things 1.) i might not have the gas cap on all the way and the gas is evaporating out the nozzle (this is not true my gas cap is always on tight) 2.) the temp of the engine mixed with the temp in the air is causing me to burn/evaporate excess fuel. (this may be possible idk) 3.) my A/C is burning my fuel (i dont think its this either but i could be wrong i just dont see how my A/C could eat all that gas) 4.) i think it may be my o2 sensor idk

so i have a diagnostics appointment with the dealer Monday at 8 a.m. and i have to leave it there. they dont know whats wrong with it exactly because my check engine light isnt on so they cant hook the computer up to my car and find out whats wrong with it. so they are gonna charge me $75 an hour until they find whats wrong with my car and idk how long its gonna take and i dont wanna pay out the ass because i cant (money is tight as hell right now).

so if anyone has any good input and might know how to fix it or whats wrong with it PLEASE PLEASE PLEASE let me know. thanks much.peace.

Instant message me at BLKVR6pwr if u have any ideas or whatnot.
 

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Tell them to work on it a max of XX hours. If you only want them to look for an hour, say only look for an hour that's it. Then hammer them with questions on what they did/didn't find.

it is hard to say. You could have gottem some really really really bad gas. It is also very humid out lately, so the air fuel mix will be different probably every 10 minutes. Most of my cars are running like crap because of the humidity, as you will probably find other cars (eg. race cars because they are sensative to weather changes). Air really eats away at the HP. Ever feel how much more power (especially in a small four)you feel when you turn it off - going up a hill, for example. I could in one of my old A2s. Air conditioning could be a possibility. I'm not sure if the speed of the fan has something to do with it. Not sure if it really pulls that many more volts when it is on low or high. I assume just because it is on, regardless of the speed, it will still be pulling down HP.

Hear any knocking or pinging at all? There could be a leak, so check that out. If the 02 sensor is going, you would know it by the REALLY bad performance and daily drivability. Or at least when mine go on the Jeep, I know it.

[ July 10, 2003: Message edited by: Emily ]
 

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Jacob, check the pipe that leads to the engine for leaks (after the portion where the Oxygen Sensor sits).

It seems as if there might be a tiny leak after the O2 sensor, so closer to the engine, as it looks like the O 2 is misreading and the Engine is compensating with FUEL for the lack of Oxygen. Try that.

Leave the engine running and wiggle the Air Tube. Check all air hoses.

To recap:

The Oxygen Sensor reads data, then sends message how much fuel to mix in, but if there is a leak after the O2 the ECU will compensate with FUEL, thus loss of MPG.

Most common problem.

[ July 10, 2003: Message edited by: TF242 ]
 

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Discussion Starter #4
ill check my hoses for leaks. but if my o2 sensor was bad would it set the check engine light off??? and how would my A/C suck up that much gas if thats the case????
 

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I am not saying you O2 is bad. The thick air tube that goes after it to the engine might be leaking air. There fore the mixture is off and the Engine is compensating with FUEL.
 

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You could have a lazy O2 sensor. Meaning not switching voltage fast enough, for the computer to see. You can always measure resistance at the sensor, to see what the resistance is.

Running the A/C takes 32% of your engine power. No matter what fan speed setting you have it on. As long as that compressor is running. So take that into account when you look at you gas gauge. The engine has to run that much harder to compensate for the use of the A/C. And in turn burn that much more fuel trying to run that hard.
 

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Hey Thomas, I am confused, are you talking about the O2 sensor or the MAF? I thought the O2 was in the exhaust, and the MAF told the engine how much oxygen it was getting. O2 is actually ozone, which is the "harmful pollutant" that the government makes us al monitor now.
 

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<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by fli gti:
Hey Thomas, I am confused, are you talking about the O2 sensor or the MAF? I thought the O2 was in the exhaust, and the MAF told the engine how much oxygen it was getting. O2 is actually ozone, which is the "harmful pollutant" that the government makes us al monitor now.<HR></BLOCKQUOTE>

He was talking about the O2 sensor. The MAF measures the air entering the engine. The O2 measures air exiting the engine so it can try to keep the fuel trim at a perfect 14.7 to 1 ratio.
The only time the computer reads the O2 sensors is when the car is in Closed Loop, or the engine is hot.
More Oxygen in exhaust means you have a Lean condition, and when there is less Oxygen you have a rich condition.
 

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Chuck is right on the O 2 sensor (write up), however:

I meant the MAF (which still has Oxygen sensor in it) as it measures the air entering the engine (which Chuck described correctly), but the tube that might be leaking is after the measurement from MAF as the leak is in between the MAF and the ENGINE.

So the MAF said X amount of air coming in, but it will be incorect due to the leak, thus the engine will compensate in fuel.

I'm sorry I kept on referring to it as Oxygen Sensor dunno what I was thinking.

The O2 on the catalytic converter measures the air afterwards. Thus 2 sensors are there. But the one after CAI/ air filter is referred to as MAF. Same purpose.
 
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