2.9l bogs at highway speeds

[ckblum]

I dont have a glasspack, I dont really have a functioning muffler at all and it still backfires like crazy. Im pretty sure its my head gasket because the previous owner said moisture was getting in the cylinder so he left the spark plug off.

 

[WhiteBroncoII2WD]

well, i jus came back from my trip, and it did the same problem but worse, would not hold in 5 on the highway and in 4 you had to have you foot to the floor or it would bog and sputter.

it dose have the duel fuel fitlers on it, which i havn't noticed till now, the in line one is new, new plugs , wires, cap and rotor, the in tank fuel pump is 3 years old, did it when the new fuel tank went in.


any ideas, i am going to get a fuel pressure gage and try that out


thanks
Kris

any news sweetsride? I second the idea regarding the O2 sensor

 

[sweetsride]

well, i was out on the weekend, it ran fine going out, wheeling all day and coming home i notice the temp gague was sitting at 210-220(mechanical gague) going up a hill an dit did it again, this time i let of for 5 sec or so, got back on it and it was fine...

why would the O2 sensor be causing this problem? should i put a new on in or just try running with out it?


thanks
Kris

 

[WhiteBroncoII2WD]

well, i was out on the weekend, it ran fine going out, wheeling all day and coming home i notice the temp gague was sitting at 210-220(mechanical gague) going up a hill an dit did it again, this time i let of for 5 sec or so, got back on it and it was fine...

why would the O2 sensor be causing this problem? should i put a new on in or just try running with out it?


thanks
Kris

In open loop operation the computer uses tables to determine the appropriate amount of fuel for the engine (start up, wide open throttle, consistent flocculation of engine speed and when the O2 sensor has failed). In closed loop the O2 sensor is used to determine how much fuel is needed while still use fuel maps. The guess would be that at a consistent highway speed if the O2 sensor is not working the computer is going into limp home mode. The other fuel filter or even a fuel pump still could be the cause and if you haven’t already changed the other filter I would suggest do so, but the O2 sensor would be where I would investigate, by pulling codes on a warmed up engine.

 

[CraigK]

If you simply disconnect the O2 sensor (two minutes) and the problem disappears, you've found the culprit, or at least have a big clue as to what the problem might be (fuel mix). If the problem persists, reconnect the O2 sensor (two and a half minutes) and try something else. (I doubt a failing O2 sensor alone would cause a serious and intermittent coolant temperature spike.)

I spend literally years (and $$$) chasing down an engine bogging problem (at highway speeds) that was instantly gone when the O2 sensor was disconnected. Duh!

CraigK

 

[MAKG]

If you simply disconnect the O2 sensor (two minutes) and the problem disappears, you've found the culprit, or at least have a big clue as to what the problem might be (fuel mix). If the problem persists, reconnect the O2 sensor (two and a half minutes) and try something else. (I doubt a failing O2 sensor alone would cause a serious and intermittent coolant temperature spike.)

I spend literally years (and $$$) chasing down an engine bogging problem (at highway speeds) that was instantly gone when the O2 sensor was disconnected. Duh!

CraigK

Not good advice. Disconnecting a critical sensor causes the emissions system to ignore just about everything and guess at fuel delivery. It doesn't tell you much at all. OF COURSE everything changes.

 

[CopyKat]

Have you checked the timing??