why the significant gas mileage difference?

What mileages do they get?

---
Ed Light

Better World News TV Channel:
http://realnews.com

Bring the Troops Home:
http://bringthemhomenow.org
http://antiwar.com

Send spam to the FTC at
spam.DeleteThis@uce.gov
Thanks, robots.
 >> Stay informed about: why the significant gas mileage difference? 

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 pm, al <abuo....RemoveThis@msn.com> wrote:
> On Apr 19, 7:44 pm, nucleus <rose122....RemoveThis@yahoo.com> wrote:
>
>
>
>
>
> > have been driving a 94 and 96 nissan sentra for several years.  THE
> > 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.  no dragging brakes.
>
> > the 96 has a different shaped body and is presumably more
> > aerodynamically
> > efficient.  however, both autos are driven in the same city & highway
> > mileage
> > conditions.  the 96 gets better mileage in city driving, than does the
> > 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?  If 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.  Beyond 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.  Good luck.  Al- Hide quoted text -
>
> - Show quoted text -
 >> Stay informed about: why the significant gas mileage difference? 

On Apr 20, 7:24 am, nucleus <rose122....RemoveThis@yahoo.com> 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 pm, al <abuo....RemoveThis@msn.com> wrote:
>
>
>
> > On Apr 19, 7:44 pm, nucleus <rose122....RemoveThis@yahoo.com> wrote:
>
> > > have been driving a 94 and 96 nissan sentra for several years.  THE
> > > 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.  no dragging brakes.
>
> > > the 96 has a different shaped body and is presumably more
> > > aerodynamically
> > > efficient.  however, both autos are driven in the same city & highway
> > > mileage
> > > conditions.  the 96 gets better mileage in city driving, than does the
> > > 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?  If 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.  Beyond 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.  Good luck.  Al- Hide quoted text -
>
> > - 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 port 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
 >> Stay informed about: why the significant gas mileage difference? 

no codes are being set, ie, neither check engine light is on.

i am aware of the OBD-I and OBD-II but are you saying that
an OBD scan device will tell me continuous info about fuel
trim, etc?

On Apr 20, 9:52 pm, al <abuo... RemoveThis @msn.com> wrote:
> On Apr 20, 7:24 am, nucleus <rose122... RemoveThis @yahoo.com> 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 pm, al <abuo... RemoveThis @msn.com> wrote:
>
> > > On Apr 19, 7:44 pm, nucleus <rose122... RemoveThis @yahoo.com> wrote:
>
> > > > have been driving a 94 and 96 nissan sentra for several years.  THE
> > > > 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.  no dragging brakes.
>
> > > > the 96 has a different shaped body and is presumably more
> > > > aerodynamically
> > > > efficient.  however, both autos are driven in the same city & highway
> > > > mileage
> > > > conditions.  the 96 gets better mileage in city driving, than does the
> > > > 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?  If 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.  Beyond 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.  Good luck.  Al- Hide quoted text -
>
> > > - 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 port 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- Hide quoted text -
>
> - Show quoted text -
 >> Stay informed about: why the significant gas mileage difference? 

"nucleus" <rose122550.DeleteThis@yahoo.com> wrote in message
news:fda31907-0d64-4083-ac0f-4b3f9d7bc9f6@24g2000hsh.googlegroups.com...
> have been driving a 94 and 96 nissan sentra for several years. THE
> 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. no dragging brakes.
>
> the 96 has a different shaped body and is presumably more
> aerodynamically
> efficient. however, both autos are driven in the same city &
> highway
> mileage
> conditions. the 96 gets better mileage in city driving, than does
> the
> 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?

How carefully are you checking your mileage?
Have you checked the odometers against each other? (i.e., Are both
cars showing the same number of miles for a given identical trip?)
The 1996 has slightly higher HP (115 vs 110 for the '94). I assume
this is because the 1996 engine is slightly more efficient (higher
compression ratio, or less internal friction, or more efficient intake
tract). I doubt the difference is worth 4 mpg, but it might be worth
some improvement.
Have you weighed the cars?
The 1996 actually has about 7% greater frontal area, so unless it has
much more aerodynamic shape, there is likely to be little difference
in fuel economy do to aerodynamic drag.
The "combined" EPA estimated mileage for the 1994 was 26 mpg. For the
1996 it was 28 mpg. So I would expect the 1996 to get slightly better
mileage. Given the normal variation in vehicles, and mileage
estimates, I'd say the variation you are seeing between the two cars
is reasonable. The fueleconomy.gov web page also includes MPG
estimates from actual drivers. Unfortunately there were not enough
people posting for cars like yours to draw any reasonable conclusions
(two drivers of 1994 Sentras averaged 30.4 mpg, one driver of a 1996
averaged 38 mpg).

Ed
 >> Stay informed about: why the significant gas mileage difference? 

My 1999 Sentra with the 1.6 liter mill gets 45 on the highway, in the
mountains, with Tufoil in it. I don't go over 55 mph. I didn't check the
mileage before putting in the Tufoil. When it drops to idle it often
dallies at 1100 rpm before dropping all the way, and I think that's the
throttle setting where it used to do 700 rpm. A long time ago I put
Tufoil in a Dodge slant 6 and the idle slowly came up to where I was
afraid to put it in Drive, and had to learn how to set the idle.

But never put Tufoil in an engine that's not totally broken in.

Next: It will go in the tranny and axles.
---
Ed Light

Better World News TV Channel:
http://realnews.com

Bring the Troops Home:
http://bringthemhomenow.org
http://antiwar.com

Send spam to the FTC at
spam DeleteThis @uce.gov
Thanks, robots.
 >> Stay informed about: why the significant gas mileage difference? 

On Apr 25, 11:27 am, Jim Yanik <jya... DeleteThis @abuse.gov> wrote:
> Codifus <codi... DeleteThis @optonline.net> wrote innews:4811f577$0$15157$607ed4bc@cv.net:
>
>
>
> > nucleus wrote:
>
> >> 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?
>
> > Yes, the O2 sensor. The main one sticking into the exhaust manifold.
> > Replace it on the 94 motor. O2 sensors can get "tired" without tripping
> > the computer code.
>
> > I replace a tired O2 on my 99 Sentra and the car came alive. The car
> > felt more powerful and the gas mileage went up. The original O2 was not
> > pulling any codes.
>
> > Also, the coolant temp sensor gets "tired" as well. When its faulty, it
> > keeps teling the computer that the engine is cold when it isn't so the
> > computer keeps running the car rich.
>
> > Now, which one to replace? The O2, because the bad CTS symptoms inlclude
> > bad gass mileage AND the car runing a little cool. You would have
> > noticed that your temp gage was sitting a little lower than normal.
>
> > CD
>
> I never heard of a coolant temp sensor getting "tired";all they are is a
> NTC thermistor,a temp sensitive resistor. I had one go open,on my Integra
> GS-R.
>
> also,the CTS and the gauge temp sensors are separate items.
>
> --
> Jim Yanik
> jyanik
> at
> kua.net

Yup, the CTS and temp gage sensor are separate, and the CTS does get
tired. Happened in my wife's Altima. Repalcing the CTS shot the car's
gas mileage from an abysmall 21 right up to 27 mpg. CTS replacement is
slow to adapt, it takes about 3 tankfulls for the ECU to adjust.

CD
 >> Stay informed about: why the significant gas mileage difference? 

nucleus wrote:
>
> 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?

Yes, the O2 sensor. The main one sticking into the exhaust manifold.
Replace it on the 94 motor. O2 sensors can get "tired" without tripping
the computer code.

I replace a tired O2 on my 99 Sentra and the car came alive. The car
felt more powerful and the gas mileage went up. The original O2 was not
pulling any codes.

Also, the coolant temp sensor gets "tired" as well. When its faulty, it
keeps teling the computer that the engine is cold when it isn't so the
computer keeps running the car rich.


Now, which one to replace? The O2, because the bad CTS symptoms inlclude
bad gass mileage AND the car runing a little cool. You would have
noticed that your temp gage was sitting a little lower than normal.

CD
 >> Stay informed about: why the significant gas mileage difference? 

Codifus <codifus.DeleteThis@optonline.net> wrote in
news:4811f577$0$15157$607ed4bc@cv.net:

> nucleus wrote:
>>
>> 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?
>
> Yes, the O2 sensor. The main one sticking into the exhaust manifold.
> Replace it on the 94 motor. O2 sensors can get "tired" without tripping
> the computer code.
>
> I replace a tired O2 on my 99 Sentra and the car came alive. The car
> felt more powerful and the gas mileage went up. The original O2 was not
> pulling any codes.
>
> Also, the coolant temp sensor gets "tired" as well. When its faulty, it
> keeps teling the computer that the engine is cold when it isn't so the
> computer keeps running the car rich.
>
>
> Now, which one to replace? The O2, because the bad CTS symptoms inlclude
> bad gass mileage AND the car runing a little cool. You would have
> noticed that your temp gage was sitting a little lower than normal.
>
> CD
>

I never heard of a coolant temp sensor getting "tired";all they are is a
NTC thermistor,a temp sensitive resistor. I had one go open,on my Integra
GS-R.

also,the CTS and the gauge temp sensors are separate items.

--
Jim Yanik
jyanik
at
kua.net
 >> Stay informed about: why the significant gas mileage difference? 

i checked the 94 O2 sensor. it is a heated sensor. the heater
resistance is within spec and, upon running the motor, the
sensor gave readings that are within spec.

so i checked the CTS while it was warm and watched the
resistance increase with temp decrease, all within spec.

these 2 sensors on the 94 apparently are working properly.

any other suggestions?
--------------------------------------------------------------------------------------

On Apr 25, 10:45 am, codifus <codi... DeleteThis @optonline.net> wrote:
> On Apr 25, 11:27 am, Jim Yanik <jya... DeleteThis @abuse.gov> wrote:
>
>
>
>
>
> > Codifus <codi... DeleteThis @optonline.net> wrote innews:4811f577$0$15157$607ed4bc@cv.net:
>
> > > nucleus wrote:
>
> > >> 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?
>
> > > Yes, the O2 sensor. The main one sticking into the exhaust manifold.
> > > Replace it on the 94 motor. O2 sensors can get "tired" without tripping
> > > the computer code.
>
> > > I replace a tired O2 on my 99 Sentra and the car came alive. The car
> > > felt more powerful and the gas mileage went up. The original O2 was not
> > > pulling any codes.
>
> > > Also, the coolant temp sensor gets "tired" as well. When its faulty, it
> > > keeps teling the computer that the engine is cold when it isn't so the
> > > computer keeps running the car rich.
>
> > > Now, which one to replace? The O2, because the bad CTS symptoms inlclude
> > > bad gass mileage AND the car runing a little cool. You would have
> > > noticed that your temp gage was sitting a little lower than normal.
>
> > > CD
>
> > I never heard of a coolant temp sensor getting "tired";all they are is a
> > NTC thermistor,a temp sensitive resistor. I had one go open,on my Integra
> > GS-R.
>
> > also,the CTS and the gauge temp sensors are separate items.
>
> > --
> > Jim Yanik
> > jyanik
> > at
> > kua.net
>
> Yup, the CTS and temp gage sensor are separate, and the CTS does get
> tired. Happened in my wife's Altima. Repalcing the CTS shot the car's
> gas mileage from an abysmall 21 right up to 27 mpg. CTS replacement is
> slow to adapt, it takes about 3 tankfulls for the ECU to adjust.
>
> CD- Hide quoted text -
>
> - Show quoted text -
 >> Stay informed about: why the significant gas mileage difference? 

nucleus wrote:
> i checked the 94 O2 sensor. it is a heated sensor. the heater
> resistance is within spec and, upon running the motor, the
> sensor gave readings that are within spec.
>
> so i checked the CTS while it was warm and watched the
> resistance increase with temp decrease, all within spec.
>
> these 2 sensors on the 94 apparently are working properly.
>
> any other suggestions?
> --------------------------------------------------------------------------------------
>
> On Apr 25, 10:45 am, codifus <codi....DeleteThis@optonline.net> wrote:
>
>>On Apr 25, 11:27 am, Jim Yanik <jya....DeleteThis@abuse.gov> wrote:
>>
>>
>>
>>
>>
>>
>>>Codifus <codi....DeleteThis@optonline.net> wrote innews:4811f577$0$15157$607ed4bc@cv.net:
>>
>>>>nucleus wrote:
>>
>>>>>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?
>>
>>>>Yes, the O2 sensor. The main one sticking into the exhaust manifold.
>>>>Replace it on the 94 motor. O2 sensors can get "tired" without tripping
>>>>the computer code.
>>
>>>>I replace a tired O2 on my 99 Sentra and the car came alive. The car
>>>>felt more powerful and the gas mileage went up. The original O2 was not
>>>>pulling any codes.
>>
>>>>Also, the coolant temp sensor gets "tired" as well. When its faulty, it
>>>>keeps teling the computer that the engine is cold when it isn't so the
>>>>computer keeps running the car rich.
>>
>>>>Now, which one to replace? The O2, because the bad CTS symptoms inlclude
>>>>bad gass mileage AND the car runing a little cool. You would have
>>>>noticed that your temp gage was sitting a little lower than normal.
>>
>>>>CD
>>
>>>I never heard of a coolant temp sensor getting "tired";all they are is a
>>>NTC thermistor,a temp sensitive resistor. I had one go open,on my Integra
>>>GS-R.
>>
>>>also,the CTS and the gauge temp sensors are separate items.
>>
>>>--
>>>Jim Yanik
>>>jyanik
>>>at
>>>kua.net
>>
>>Yup, the CTS and temp gage sensor are separate, and the CTS does get
>>tired. Happened in my wife's Altima. Repalcing the CTS shot the car's
>>gas mileage from an abysmall 21 right up to 27 mpg. CTS replacement is
>>slow to adapt, it takes about 3 tankfulls for the ECU to adjust.
>>
>>CD- Hide quoted text -
>>
>>- Show quoted text -
>
>
You know what? This may be by design. Looking at the history of Nissan
engines, if you look at the SR20DE, the 91-94 version was the most
powerfull. Why? Because that motor had faster, more aggressive cam
profiles. Those cam profiles killed fuel economy and emissions. The
newer SR20DE motors were less powerful but cleaner due to the milder cams.

Something tells me your 94 Sentra has more aggrressive cam profiles in
its GA16DE motor than the 96 Sentra. In other words, the 94 should feel
a bit more powerful than the 96 motor.

If that is what you observe than that's just the way it is.

CD
 >> Stay informed about: why the significant gas mileage difference? 

Codifus <codifus DeleteThis @optonline.net> wrote in
news:481b7fb7$0$11624$607ed4bc@cv.net:

> nucleus wrote:
>> i checked the 94 O2 sensor. it is a heated sensor. the heater
>> resistance is within spec and, upon running the motor, the
>> sensor gave readings that are within spec.

this doesn't tell you if the O2 sensor is "SLOW";taking *too long* to
respond to O2 changes,which can cause the ECM to run the motor too rich.
From what I've read,the O2S should begin switching between 0.1v and 1.0v in
2 minutes or less after starting from cold.


>>
>> so i checked the CTS while it was warm and watched the
>> resistance increase with temp decrease, all within spec.
>>
>> these 2 sensors on the 94 apparently are working properly.
>>
>> any other suggestions?
>> ----------------------------------------------------------------------
>> ----------------
>>
>> On Apr 25, 10:45 am, codifus <codi... DeleteThis @optonline.net> wrote:
>>
>>>On Apr 25, 11:27 am, Jim Yanik <jya... DeleteThis @abuse.gov> wrote:
>>>
>>>
>>>
>>>
>>>
>>>
>>>>Codifus <codi... DeleteThis @optonline.net> wrote
>>>>innews:4811f577$0$15157$607ed4bc@cv.net:
>>>
>>>>>nucleus wrote:
>>>
>>>>>>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?
>>>
>>>>>Yes, the O2 sensor. The main one sticking into the exhaust
>>>>>manifold. Replace it on the 94 motor. O2 sensors can get "tired"
>>>>>without tripping the computer code.
>>>
>>>>>I replace a tired O2 on my 99 Sentra and the car came alive. The
>>>>>car felt more powerful and the gas mileage went up. The original O2
>>>>>was not pulling any codes.
>>>
>>>>>Also, the coolant temp sensor gets "tired" as well. When its
>>>>>faulty, it keeps teling the computer that the engine is cold when
>>>>>it isn't so the computer keeps running the car rich.
>>>
>>>>>Now, which one to replace? The O2, because the bad CTS symptoms
>>>>>inlclude bad gass mileage AND the car runing a little cool. You
>>>>>would have noticed that your temp gage was sitting a little lower
>>>>>than normal.
>>>
>>>>>CD
>>>
>>>>I never heard of a coolant temp sensor getting "tired";all they are
>>>>is a NTC thermistor,a temp sensitive resistor. I had one go open,on
>>>>my Integra GS-R.
>>>
>>>>also,the CTS and the gauge temp sensors are separate items.
>>>
>>>>--
>>>>Jim Yanik
>>>>jyanik
>>>>at
>>>>kua.net
>>>
>>>Yup, the CTS and temp gage sensor are separate, and the CTS does get
>>>tired. Happened in my wife's Altima. Repalcing the CTS shot the car's
>>>gas mileage from an abysmall 21 right up to 27 mpg. CTS replacement
>>>is slow to adapt, it takes about 3 tankfulls for the ECU to adjust.

Or maybe you were low on coolant and the sensor was not immersed in it.
Sorry,but thermistors don't get "tired". Maybe it changed in value,skewing
the ECM map.An ohmmeter would tell.

but your comment made me think I should be checking my SpecV's CTS and
coolant level,as my mileage is a lousy 18MPG.(72K miles)
That and the primary O2S.

>>>
>>>CD- Hide quoted text -
>>>
>>>- Show quoted text -
>>
>>
> You know what? This may be by design. Looking at the history of Nissan
> engines, if you look at the SR20DE, the 91-94 version was the most
> powerfull. Why? Because that motor had faster, more aggressive cam
> profiles. Those cam profiles killed fuel economy and emissions. The
> newer SR20DE motors were less powerful but cleaner due to the milder
> cams.
>
> Something tells me your 94 Sentra has more aggrressive cam profiles in
> its GA16DE motor than the 96 Sentra. In other words, the 94 should
> feel a bit more powerful than the 96 motor.
>
> If that is what you observe than that's just the way it is.
>
> CD
>



--
Jim Yanik
jyanik
at
kua.net
 >> Stay informed about: why the significant gas mileage difference? 

Jim Yanik wrote:

> Or maybe you were low on coolant and the sensor was not immersed in it.
> Sorry,but thermistors don't get "tired". Maybe it changed in value,skewing
> the ECM map.An ohmmeter would tell.
>
> but your comment made me think I should be checking my SpecV's CTS and
> coolant level,as my mileage is a lousy 18MPG.(72K miles)
> That and the primary O2S.

Not in my cars. Whenever I have a problem I always rule out the basics;
low oil level, coolant low, need of a tuneup, etc.

I always try the least costly solution and move up.

I bet your primary O2 is done. With the CTS, the basic symptom is that
you should notice that your temp gage sits a little lower than what your
normally see.

CD
 >> Stay informed about: why the significant gas mileage difference?