26 MPG with intermittent P304

[urdrwho]

The car runs well at highway speeds, no notice of any burps and has a lot of pep. Last night I made a 90 mile round trip, most was on the highway doing about 45 MPH. There was a 10 minute stop and go traffic jam.

 

On the trip my MPG was @26 and that is very acceptable for a 97 Outback AWD. Around town in my stop and go the MPG varies from a low 15 to around 17.

 

It all makes me wonder about the intermittent P304. I never, ever, not once in 5,500 miles set a P304 while cruising on the highway. The code is always 100% of the time set either while waiting at a stop light or as I take off from the stop light.

 

If the misfire is a mechanical problem wouldn't the code appear on the highway, off the highway, sitting, etc?

[johnegg]

wires first.

then maybe plugs.

 

or if you have the time,

move the #4 wire to the front, either #1 or #2.

 

see if the misfire moves as well.

 

car????????????????

[urdrwho]

New wires

New plugs

New coil

I can move the #4 wire to the #2 coil hole?

97 outback limited with 2.5

 

wires first.

then maybe plugs.

 

or if you have the time,

move the #4 wire to the front, either #1 or #2.

 

see if the misfire moves as well.

 

car????????????????

[johnegg]

if, big IF, you have checked everything else,

do a compression tests on #4.

 

if the valves are not, were not, adjusted at 105k, you could have a burned exhaust valve.

for dome reason i do not know, #4 is the first to go.

 

you can do the compression test any time.

but i would not ASSUME a burnt valve until you have checked all the rest.

[urdrwho]

John, to check the timing can the side covers be removed without removing a lot of other bits? If so, I guess that I can then get a socket on the crank nut without removing the fans.

 

 

if, big IF, you have checked everything else,

do a compression tests on #4.

 

if the valves are not, were not, adjusted at 105k, you could have a burned exhaust valve.

for dome reason i do not know, #4 is the first to go.

 

you can do the compression test any time.

but i would not ASSUME a burnt valve until you have checked all the rest.