[V8] MPG - now stalling

d saad dsaad at icehouse.net
Wed Jan 31 20:22:25 EST 2007

Now that I have had TWO ignition caps fail the same way - by slowly
degrading and arcing out to the plastic ground shield (both times to #1
cylinder), I would give the ignition system a good look. In my case,
performance slowly degraded and mileage went with it.

On the O2
sensor, is the engine and exhaust pipe well grounded? Some have gone with
the Ford 4-wire sensor to get around this problem. Since you seem to run
fine in open-loop mode, there has to be some input to the computer that is

You have these inputs:
intake air temp
flow sensor
ignition sensors (three of them)
coolant temp
road speed
brake pedal (I think anyway)

monitored but important - fuel pressure and flow.

And the
automatic maybe has some inputs I would not know about.
dragging brake(s)
Alignment way out of whack - or tires way under
inflated - or wrong size for the speedo - causing you to think the MPG is
off - or the speedo itself may be reading wrong. I know mine is off a few


> Ok guys,
>    This is
what has happened so far. (some of it is a re-cap)
> 1. When I
bought the car, before I even had driven it I replaced the o2s
2. When I start driving the car I notice really bad gas milage (14mpg
> -used to 18.5mpg on my last v8 with more miles.
> 3. Check
codes, get 2341 - out of range - causes could be: leaks in
intake/exhaust, high or low fuel pressure, Ignition failure, bad o2s
> 4. Check o2s for output - seems to be functioning properly.
> 5. Car starts dieing intermittantly, expecially at a stop, then
> horribly on the throttle - figure it is low ATF - find
out later it isn't.
> 6. Change X-pipe with another o2s in it due
to a patch job on the original
> x-pipe (thinking this is the
cause?), find that this o2s is bad and is
> putting out no signal
at all - this throws a code 2342 - disconnected o2s
> - car runs
great with no stalling but mpg stay around 13 or so.
> 7. Change
out old o2s with the new one I had bought - car immedieatly dies
at idle - throws the 2341 code again.
> 8. Where do I go from
> I really think that I need the time to pull
apart the intake to look for a
> vaccum leak, also I need to test
fuel pressure.  I have changed the FPR
> and MAF with known good
units.  If any one has any ideas let me know -
> expecially vaccum
leaks to look for - I can't afford the gas anymore, and
> besides
it bugs me to know that the car isn't right!
>              Jason
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