better have a look to see if your egr has been removed. if your egr is open all the time that would screw the mpg

 

thanks! ill definitely look into that. im taking it to the shop tomorrow

 

Start a new thread in this forum section please

 

Not necessarily... If possible, I'd check the functionality of any part before replacing it with some data logging and other experimentation. There's no use in replacing a healthy sensor or part.

 

I am talking about parts that are suppost to be replaced based on life cycle. Imagine how pissed you would be if you had a miss, the mechanic spent 2 hours checking everything ($170) just to tell you "you need to spend $18 fuel filter" If the car is not up to date with the required mainteance that should be done first. Now if he knows everything is up to date I agree.

 

if fouled or aging 02 sensors can show a proper reading that is false. that can cause the motor to run rich but show its lean on a datalog.

 

I'm not saying that you should avoid regular maintenance on your car... I just think you should do a bit of digging before you go spending uncontrollably on parts that may not be the root of your problem. You should do a bit of problem solving first.

And Craby, when it comes to O2 sensors the best thing to do would be to check the datalog, check the sensor visually for fouling, and then a voltage test using a propane torch + multimeter to gauge the health of the zirconia element. O2s are expensive, there's no point in buying new parts if the old ones are in perfect working order.

 

yes that test "almost" always works.

 

I didn't intend to start an argument on doing normal maintenance. I was hoping to get him thinking that not all codes will set an SES light.

Going to the auto parts store and pulling codes is free for the most part. If there is a code stored, then he would have an idea of where a potential problem would be.

For my money, modern cars (I classify all 4th gens as modern) would not show a 50% reduction in mileage just on "tune up" parts, without there being some other symptoms (back firing, weak acceleration, hard starting, etc). Since the only thing the OP mentioned was the sucky mileage, my first inclination would be to pull any codes.

The only thing pulling codes costs is time and it could easily save a lot of money on unnecessary parts, especially since he has an OBDII car. Of course, eventually the "tune up" parts will require replacement, but if they are not the cause of his mileage problem, I fail to see the reason to just replace them.

 

+1 on what gorn is saying, when i was getting 7mpg city until i changed the coolant temp sensor which bumped me instantly to 12.5, almost all the parts that i`ve taken off the car has been original so far, so maintenance is key