gas mileage

what can i check for,for bad gas mileage. this is a 2000 and has a 3.4.

are you experiences bad power too, then it might be the cat, it was a common thing to go wrong, 00-02 cat warrenty were extended to like 8 years or 120K, so if your under that, you could get it replaced for free.

otherwise, bad MPg can be because of....

bad spark plugs
bad spark plug wires
clogged fuel filter
bad air filter
incorrect tire pressure
driving habits

and I think that about covers it.

I'd add 02 sensors to the list.

02 sensors can cause a reduction in fuel economy. They carbon up. There are two, one before the CAT convertor and one after. You can remove them and clean to see if it makes a difference. Doesn't cost much except some time. 02 sensors may not trigger an SES light or set DTC error codes unless the efficiency drops down to around 60%.

I knew there was something I forgot, thanks bnaylor

How easy/hard is it to remove the O2 sensors?... Are they both accessible from under the car only?...

yep, under car only, for the most part, in our cars we have 2 of them, the first one is the one is for calibrating a/f ratios, and teh second is for cat flow.

as for removing them, use a wrench, turn, remove. one is located in our exhaust maniflods IIRC, and the other is located in the u-bend after the cat.

How easy/hard is it to remove the O2 sensors?... Are they both accessible from under the car only?...

Like changing out a spark plug. For the rear you have to get under the car. For the front access is from the engine compartment. Autozone has a universal 02 sensor socket for around $9.00 which makes removal easy. It has cutout for the wiring harness.

Each 02 sensor electrical connector will have a blue safty tab that must be cut off before you can undo the electrical connector on each sensor.

When re-installing put a light coat of anti-seize compound on the 02 sensor threads before screwing them back into the exhaust pipe. Good luck!

I see prices at AutoZone anywhere from about $30 to $70 each for the O2 sensors... Which manufacturer and what price is the best?

I see prices at AutoZone anywhere from about $30 to $70 each for the O2 sensors... Which manufacturer and what price is the best?

If you decide to replace them, which is not a bad idea stick with AC Delco OEM type only. Do not use the Bosch brand found at Autozone. There are a bunch of AC Delco OEM 02 sensors for your car on EBay at a much better price than the dealer.

AC Delco part numbers:

Front AFS 109
Rear AFS 141

I have an '01 LS, 3.8L, with only about 50K miles... Think it's time to change them or wait longer?...

I have an '01 LS, 3.8L, with only about 50K miles... Think it's time to change them or wait longer?...

You might consider cleaning them but I would not replace them unless getting a SES light and DTC error codes related to Position 1 or 2 02 sensor.

Up until I sold my '01 Impala LS (85K miles) I still had the original 02 sensors and gas mileage was good.

I have an '01 LS, 3.8L, with only about 50K miles... Think it's time to change them or wait longer?...

I have a 01 LS and just changed mine at 167000 miles.My lite came on and the code was 02 sensors.I bought both at NAPA for $125.

What do you clean them with? Carb cleaner?

What do you clean them with? Carb cleaner?

You can use carb cleaner, throttle body cleaner or fuel injector cleaner.

Important thing is to make sure the vanes have no carbon buildup. After cleaning you can hold the 02 sensor up to a light and you should see light through each vane. The vanes help channel or catch the exhaust gases for the sensor section to pick up. Good luck!

Thanks dude... You really know your stuff!!