I have been getting really crappy fuel mileage (less than 220 miles per tank) when I used to get close to 400. I just checked my ECU, got a normal reading. Now...

1) Does it matter what position you leave the ECU control screw in when done pulling codes? I just put it roughly somewhere in between the two extremes, car seems to run the same as before I checked, but I want to make sure there's not some specific place to put the screw for normal operation.

2) I've searched about the mileage problem and pretty much ended up thinking I should go replace the O2 sensor. Now...even after looking at chilton's, I can't seem to find the O2 sensor. Can anyone give specifics of how to locate it, maybe a pic?

3) Is it bad that my alternator belt is super-duper tight? Shouldn't it have some play in it when you press on it?

Thanks guys

 

Measure the o2 sensor with a volt meter, at 2k rpm it should bounce between 0-1v more than 5 times in 10 seconds. Next get a new gas cap and check the air pressure in tires. Check the engine temp sensor and emission hoses/EVAP/EGR for proper function.

 

If your 02 sensor has more than 70k on it THEN REPLACE IT.

The ecu screw should be in the counterclock wise position when your are done.

 

I think I will replace the O2 sensor, I just need to know physically where it is located, I can't find it by looking at the picture in my Chilton's.

Thanks for the ECU screw advice, I am going to go put in all the way counter-clockwise now - it was in the middle before I checked it, but the little piece of plastic covering it had already been removed so maybe the last owner just didn't put it back right.

 

it on the pipe under the car. right b4 the cat converter. has some wires coming out. not for sure but i tjink thats where it it

 

That's right, underneath the car, just before the cat.