On Apr 20, 7:24=A0am, nucleus <rose122...@[EMAIL PROTECTED]
> wrote:
> thanks al, plugs look identical, temp guage on both are in approximate
> same position when at operating temp.
>
> what kind of "scan tool" is this that will measure fuel trim and
> ox sensor operation?
>
> about gas mileage, for 2 years the 94 averages 33.3 mpg and the 96
> averages 37.7 mpg; long trips are driven at 65 mph max, short highway
> trips are driven at 55 mph max.
>
> On Apr 19, 8:05=A0pm, al <abuo...@[EMAIL PROTECTED]
> wrote:
>
>
>
> > On Apr 19, 7:44=A0pm, nucleus <rose122...@[EMAIL PROTECTED]
> wrote:
>
> > > have been driving a 94 and 96 nissan sentra for several years.
=A0THE
> > > 96 CONSISTENTLY AVERAGES OVER 4 MPG GREATER THAT THE 94.
>
> > > both are stock cars, 4 door, 1.6 liter engines, 4 speed/overdrive
auto=
> > > transmissions, have same brand & size tires and use the same tire
> > > pressures, which are adjusted monthly. both cars have almost
identical=
> > > total mileage. =A0no dragging brakes.
>
> > > the 96 has a different shaped body and is presumably more
> > > aerodynamically
> > > efficient. =A0however, both autos are driven in the same city &
highwa=
y
> > > mileage
> > > conditions. =A0the 96 gets better mileage in city driving, than does
t=
he
> > > 94.
>
> > > is there some sensor, that DOES NOT set a computer code, that can
> > > cause
> > > the computer to run the 94 engine richer than the 96 engine?
>
> > Do the plugs look different between the two cars? =A0If one is really
> > runner richer the plugs on that one might show more carbon deposits.
> > I presume the thermostat is working well on both and is the same
> > design temperature. =A0Beyond that, if you really want to track it
down
> > you can start by putting a scan tool on it and observing the fuel trim
> > and the oxygen sensor behavior. =A0Good luck. =A0Al- Hide quoted text
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>
> > - Show quoted text -- Hide quoted text -
>
> - Show quoted text -
Seems unlikely but I suppose with virtually everything else being
eliminated, you have to consider the odometer calibration may be
different. I presume both vehicles use the same type of oil also.
Post 1996 vehicles sold in the US must have an OBD-II diagnostic
system to monitor pollution related parameters such as fuel trim,
sensors etc. When something is out of spec, the check engine light
comes on and a code is set. But all of that data is available for
viewing with a special purpose piece of diagnostic equipment known as
a scan tool that plugs into a data ****t that all OBD-II equipped cars
have just under the dashboard on the driver's side. Pre-1996 cars had
OBD-I systems so I'm not sure what diagnostic system you've got on
each car. With all the obvious things eliminated, seems like the next
way to pursue this is through analyzing the engine data stream.
That's a whole other level of complexity. Good luck. Al
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