15 mpg? What's going on?

Splinter · Post by **Splinter** » Sun Sep 25, 2005 1:22 am

Any idea why I'd only be getting 15mpg? The last two tanks have gone like that. I know this car isnt that fuel efficient, but that seems kinda extreme.

Manarius · Post by **Manarius** » Sun Sep 25, 2005 1:27 am

Leaking fuel? Bad Coil Pack? Yucky Spark Plugs? Bad Sensors? I'd check those things...

Splinter · Post by **Splinter** » Sun Sep 25, 2005 1:44 am

How do I check the sensors?

Manarius · Post by **Manarius** » Sun Sep 25, 2005 1:46 am

Splinter wrote:How do I check the sensors?

Check their voltages...read pinouts from the ECU..etc...

You might want to try to clean the MAF. You might also want to try replacing the PCV valve..that can kill mileage too.

All_talk · Post by **All_talk** » Sun Sep 25, 2005 2:21 am

Hey Splinter

That car always did about 26mpg hiway, I'd think it should be good for at least 20-21 around town if you're not spoolin the turbo all the time.

You dont have a check engine light do you? If you are running rich in feedback mode (after warm up, off boost) the O2 sensor should through a code.

Gary

Splinter · Post by **Splinter** » Sun Sep 25, 2005 2:49 am

All_talk wrote:Hey Splinter

That car always did about 26mpg hiway, I'd think it should be good for at least 20-21 around town if you're not spoolin the turbo all the time.

You dont have a check engine light do you? If you are running rich in feedback mode (after warm up, off boost) the O2 sensor should through a code.

Gary

Nope, no check engine light

Although it just occured to me that I've reset the ECU a couple of times (while working on the electrics Ive disconnected the negative terminal from the battery)

Could the mileage drop that badly while the ECU is relearning?

Splinter · Post by **Splinter** » Sun Sep 25, 2005 4:05 am

Um.. where would I find the MAF sensor?

vrg3 · Post by **vrg3** » Sun Sep 25, 2005 4:08 am

It's the gizmo bolted to the air filter housing with four 10mm-head bolts.

Splinter · Post by **Splinter** » Sun Sep 25, 2005 4:10 am

vrg3 wrote:It's the gizmo bolted to the air filter housing with four 10mm-head bolts.

cheers

Just use electrical contact cleaner on it?

vrg3 · Post by **vrg3** » Sun Sep 25, 2005 4:16 am

Contact cleaner might be good, but I've always used either isopropanol (swish it around in a ziploc bag of the stuf) or brake cleaner (spray it very gently).

Splinter · Post by **Splinter** » Mon Sep 26, 2005 3:32 am

Splinter wrote:Although it just occured to me that I've reset the ECU a couple of times (while working on the electrics Ive disconnected the negative terminal from the battery)

Could the mileage drop that badly while the ECU is relearning?

Anyone know the answer to this?

vrg3 · Post by **vrg3** » Mon Sep 26, 2005 4:02 am

Yes, mileage is usually a little low when it's learning. A couple hundred miles should be more than enough to relearn.

15 mpg still seems low though.

wiscon_mark · Post by **wiscon_mark** » Mon Sep 26, 2005 4:04 am

I got 23 when relearning, and the second tank I got 27

If it doesn't improve, then you can start panicking

Splinter · Post by **Splinter** » Thu Oct 13, 2005 4:45 am

Cleaning the MAF and replacing the PCV seems to have helped.

I'm about 1/3 of the way into the tank with 84 miles on the trip odo.

legacycentral bbs

A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans

15 mpg? What's going on?

15 mpg? What's going on?