1998 Mark VIII LSC and 1995 Mark VIII base

[1995 Mark VIII]

My brother and I both have Mark VIII's and they both average around 12 to 13 miles to the gallon. What could be causing such crappy gas mileage? O2 sensors of MAF sensor? We are both lost. We do not hot rod them around either.


Thanks, Vic

 

[Staffamerica74]

Do you put 93 in them? Changed the fuel filter lately?

 

[1995 Mark VIII]

Yes and yes they both still get the same gas mileage. :/

Thanks, Vic

 

[unity]

Its probably simple maintenance. I dont think anyone can say for sure what the issue is until you do the basics. Spark plugs/air filter/PCV valve/oil/etc...

Cleaning the MAF is easy. The O2 sensors really should be replaced every 60k. Some say 100k, but by then they are pretty spend. Given the cost, you will save that back in fuel changing early.

As for hot rodding around, thats okay to do. RPM should get over 3k regularly to exercise the IMRCs. And sometimes an "Italian Tune-Up" can do wonders.

 

[Alexander B. Sonin]

The MAF and The O2 sensors

Its probably simple maintenance. I dont think anyone can say for sure what the issue is until you do the basics. Spark plugs/air filter/PCV valve/oil/etc...

Cleaning the MAF is easy. The O2 sensors really should be replaced every 60k. Some say 100k, but by then they are pretty spend. Given the cost, you will save that back in fuel changing early.

As for hot rodding around, thats okay to do. RPM should get over 3k regularly to exercise the IMRCs. And sometimes an "Italian Tune-Up" can do wonders.

Please, what is "The MAF and The O2 sensors"?
Thanks,
Alexander.

 

[PenGun]

Please, what is "The MAF and The O2 sensors"?
Thanks,
Alexander.

Hi Alexander. The MAF is the Mass Airflow Sensor. It's the deal the air cleaner feeds. It lets the PCM know how much air is coming into the motor.

The O2 sensors are in the exhaust just behind the first set of cats and they monitor the fuel mixture. They tell the PCM what the mixture, air/fuel, is so it can adjust that as it sees fit. When it's working it's known as a closed loop and when they fail the PCM goes into open loop and guesses a lot.

I'll get that wheel to you pretty soon. I have to rip it apart to do the clockspring etc and I'll send it then. I have all but the shifter surround in wood and with that knob I got from you it is quite fine. A wood wheel will be awesome.

 

[UltimateSVT]

My brother and I both have Mark VIII's and they both average around 12 to 13 miles to the gallon. What could be causing such crappy gas mileage? O2 sensors of MAF sensor? We are both lost. We do not hot rod them around either.


Thanks, Vic

That's what ALL the Mark VIII's I've owned make when I drive them around in the city EXCLUSIVELY. As soon as you stretch their legs on the highway the gas mileage increases big time. My late '93 used to do 10.2. Both of the 97's I own now do between 11.9 & 13.7 in the city. Get on the highway, do 20-30 miles & watch that avg go up... or as soon as you get on the highway, get on that middle lane @ 60mph, reset the "MPG Average" & watch the mpg skyrocket then level out in the mid to high 20's!

It will slowly come down to your regular avg in a couple days driving around the city again.