'99 Olds Intrigue w/awful MPG need help!

Hello group.

I've a 1999 Olds intrigue (3.5l/94K) that's been getting awful fuel
economy for some time now and nothing seems to help. For the first year
or so I owned it, it consistantly got 19-20mpg in all city driving. For
the last 1.5 or so years it has dropped to 14-16mpg, usually closer to
14.

As soon as I noticed the huge difference at the pump, I started having
work done but nothing's changed. Thus far I've had new platinum plugs
put in, a $180 fuel system cleaning, tires rotated and balanced and
I've run some chevron techron thru it. I also get regular oil changes
w/mobil1 and just had the tranny fluid changed. I check tire pressure
often and drive pretty conservatively.

People have suggested the next thing I should try is replacing the
oxygen sensor, but both mechanics I've asked about it seem to think it
would be a waste, and that without a check engine light it's probably
working okay.

So really I don't know what to do, but this problem is driving me nuts!
I gotta think that something is going very wrong, but not knowing autos
very well, or being a DIYer I have to rely on the mechanics. Is there
some kind of diagnostic machine that can find the problem?

Aside from the awful mileage problem, it's been a pretty good car. I'm
just getting so frustrated with this that I'm thinking of trading it
in. Thanks in advance for any suggestions!

There is a recall on some of them because the heater hose hits the O2
sensor hard enough that it can even puncture the heater hose. This
might also do bad things for the O2 sensor or it's connections.

http://www-odi.nhtsa.dot.gov/cars/pr...ls/results.cfm

Some engines run like crap on platinum plugs also....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

wrote:
>
> Hello group.
>
> I've a 1999 Olds intrigue (3.5l/94K) that's been getting awful fuel
> economy for some time now and nothing seems to help. For the first year
> or so I owned it, it consistantly got 19-20mpg in all city driving. For
> the last 1.5 or so years it has dropped to 14-16mpg, usually closer to
> 14.
>
> As soon as I noticed the huge difference at the pump, I started having
> work done but nothing's changed. Thus far I've had new platinum plugs
> put in, a $180 fuel system cleaning, tires rotated and balanced and
> I've run some chevron techron thru it. I also get regular oil changes
> w/mobil1 and just had the tranny fluid changed. I check tire pressure
> often and drive pretty conservatively.
>
> People have suggested the next thing I should try is replacing the
> oxygen sensor, but both mechanics I've asked about it seem to think it
> would be a waste, and that without a check engine light it's probably
> working okay.
>
> So really I don't know what to do, but this problem is driving me nuts!
> I gotta think that something is going very wrong, but not knowing autos
> very well, or being a DIYer I have to rely on the mechanics. Is there
> some kind of diagnostic machine that can find the problem?
>
> Aside from the awful mileage problem, it's been a pretty good car. I'm
> just getting so frustrated with this that I'm thinking of trading it
> in. Thanks in advance for any suggestions!

wrote in message
:

> Hello group.
>
> I've a 1999 Olds intrigue (3.5l/94K) that's been getting awful fuel
> economy for some time now and nothing seems to help. For the first
> year or so I owned it, it consistantly got 19-20mpg in all city
> driving. For the last 1.5 or so years it has dropped to 14-16mpg,
> usually closer to
> 14.

Well, if you *will* drive a car with an enormous engine and fuel-wasting
automatic transmission... Maybe when fuel in the US starts to be taxed at
the same rate as in the UK, there'll be the same incentive as over here to
buy a more efficient car.

wrote:
> Hello group.
>
> I've a 1999 Olds intrigue (3.5l/94K) that's been getting awful fuel
> economy for some time now and nothing seems to help. For the first year
> or so I owned it, it consistantly got 19-20mpg in all city driving. For
> the last 1.5 or so years it has dropped to 14-16mpg, usually closer to
> 14.
>
> As soon as I noticed the huge difference at the pump, I started having
> work done but nothing's changed. Thus far I've had new platinum plugs
> put in, a $180 fuel system cleaning, tires rotated and balanced and
> I've run some chevron techron thru it. I also get regular oil changes
> w/mobil1 and just had the tranny fluid changed. I check tire pressure
> often and drive pretty conservatively.
>
> People have suggested the next thing I should try is replacing the
> oxygen sensor, but both mechanics I've asked about it seem to think it
> would be a waste, and that without a check engine light it's probably
> working okay.
>
> So really I don't know what to do, but this problem is driving me nuts!
> I gotta think that something is going very wrong, but not knowing autos
> very well, or being a DIYer I have to rely on the mechanics. Is there
> some kind of diagnostic machine that can find the problem?
>
> Aside from the awful mileage problem, it's been a pretty good car. I'm
> just getting so frustrated with this that I'm thinking of trading it
> in. Thanks in advance for any suggestions!

I would have thought that a mechanic could hook up their diagnostic
machine while the car was running and tell if there is a problem that
would cause the vehicle to run rich.

"Martin Underwood" <a@b> wrote in
:

> wrote in message
> :
>
>> Hello group.
>>
>> I've a 1999 Olds intrigue (3.5l/94K) that's been getting awful fuel
>> economy for some time now and nothing seems to help. For the first
>> year or so I owned it, it consistantly got 19-20mpg in all city
>> driving. For the last 1.5 or so years it has dropped to 14-16mpg,
>> usually closer to
>> 14.
>
> Well, if you *will* drive a car with an enormous engine and
> fuel-wasting automatic transmission... Maybe when fuel in the US
> starts to be taxed at the same rate as in the UK, there'll be the same
> incentive as over here to buy a more efficient car.
>
>

the old 'ugly american' diagnosis......hmmm, doesnt really address the
problem of mpg falling but i dont imagine that was what you wanted to do
anyway.

KjunRaven wrote in message
:

> "Martin Underwood" <a@b> wrote in
> :
>
>> wrote in message
>> :
>>
>>> Hello group.
>>>
>>> I've a 1999 Olds intrigue (3.5l/94K) that's been getting awful fuel
>>> economy for some time now and nothing seems to help. For the first
>>> year or so I owned it, it consistantly got 19-20mpg in all city
>>> driving. For the last 1.5 or so years it has dropped to 14-16mpg,
>>> usually closer to
>>> 14.
>>
>> Well, if you *will* drive a car with an enormous engine and
>> fuel-wasting automatic transmission... Maybe when fuel in the US
>> starts to be taxed at the same rate as in the UK, there'll be the
>> same incentive as over here to buy a more efficient car.
>>
>>
>
> the old 'ugly american' diagnosis......hmmm, doesnt really address the
> problem of mpg falling but i dont imagine that was what you wanted to
> do anyway.

When you have to pay our pump prices, you'll see that driving a vehicle that
does as little as 14 mpg (17.5 miles/UK gallon) is going to be VERY
expensive.

UK prices are currently about 88 pence/litre for petrol (gasoline) and 90
pence/litre for diesel. There are about 3.6 litres/US gallon, and the
exchange rate is currently about $1.96 = £1, so that gives prices of $6.21
and $6.35 respectively.

For the record, my car has averaged 50 miles/UK gallon (40 miles/US gallon)
over the seven years I've had it - that's for a 2-litre diesel.

Maybe one day the US will learn to curb its profligate waste of fuel.

"Martin Underwood" <a@b> wrote in message
...
> KjunRaven wrote in message
> :
>
> > "Martin Underwood" <a@b> wrote in
> > :
> >
> >> wrote in message
> >> :
> >>
> >>> Hello group.
> >>>
> >>> I've a 1999 Olds intrigue (3.5l/94K) that's been getting awful fuel
> >>> economy for some time now and nothing seems to help. For the first
> >>> year or so I owned it, it consistantly got 19-20mpg in all city
> >>> driving. For the last 1.5 or so years it has dropped to 14-16mpg,
> >>> usually closer to
> >>> 14.
> >>
> >> Well, if you *will* drive a car with an enormous engine and
> >> fuel-wasting automatic transmission... Maybe when fuel in the US
> >> starts to be taxed at the same rate as in the UK, there'll be the
> >> same incentive as over here to buy a more efficient car.
> >>
> >>
> >
> > the old 'ugly american' diagnosis......hmmm, doesnt really address the
> > problem of mpg falling but i dont imagine that was what you wanted to
> > do anyway.
>
> When you have to pay our pump prices, you'll see that driving a vehicle
that
> does as little as 14 mpg (17.5 miles/UK gallon) is going to be VERY
> expensive.
>
> UK prices are currently about 88 pence/litre for petrol (gasoline) and 90
> pence/litre for diesel. There are about 3.6 litres/US gallon, and the
> exchange rate is currently about $1.96 = £1, so that gives prices of $6.21
> and $6.35 respectively.
>
> For the record, my car has averaged 50 miles/UK gallon (40 miles/US
gallon)
> over the seven years I've had it - that's for a 2-litre diesel.
>
> Maybe one day the US will learn to curb its profligate waste of fuel.
>
>
Now that gas prices have leveled off, Ford Excursions with V10s and the like
are popular again. I drive an 06 Honda Accord I 4 -- which is just fine for
me with plenty of power and decent mileage around 30mpg mixed. But, most
people love their big SUVs even though they get around 10-14 mpg -- with
just one person in them going to work. The U.S. has a huge challenge in
coming up with a decent energy policy that will reduce the need for huge
imports of foreign oil. I very doubt that any polititian will want to take
that on.

>
>

wrote:
> Hello group.
>
> I've a 1999 Olds intrigue (3.5l/94K) that's been getting awful fuel
> economy for some time now and nothing seems to help. For the first year
> or so I owned it, it consistantly got 19-20mpg in all city driving. For
> the last 1.5 or so years it has dropped to 14-16mpg, usually closer to
> 14.

It seems you have the fuel system sorted if that has been cleaned, the
plugs would assume the electrics are running perfectly. What about the
vacuum system? I'm not familiar with the model, being down in
australia, but i do believe a vacuum leak can result in spark not being
advanced enough, which could be throwing the fuel management system
haywire.
Are you noticing any loss of performance? If it takes more gas to
accelerate the car than usual the problem may be as simple as sticking
brakes or clogged air filter. Speaking of which, the air intake sensor
may be playing up, making the ECU compensate for what it thinks is a
huge quantity of air coming into the engine by adding more fuel.
I'm not a mechanic, and i dont claim to be familiar with your problem,
but at least this advice may help in some way shape or form. Case and
point, stop using this group to argue which country has better choice
in vehicles, it hardly fixes the problem at hand
Hope these suggestions help

>
wrote:
>> Hello group.
>>
>> I've a 1999 Olds intrigue (3.5l/94K) that's been getting awful fuel
>> economy for some time now and nothing seems to help. For the first year
>> or so I owned it, it consistantly got 19-20mpg in all city driving. For
>> the last 1.5 or so years it has dropped to 14-16mpg, usually closer to
>> 14.
>


If I was going to just guess at what the problem could be I would
start with a MAP sensor. I have seen them fail several times and
cause this problem but no be far enough out of spec to set a code.

Steve B.

The simplest thing I can think of is to have the compression checked at
each cylinder, and make sure air cleaner isnt restricted. Low
compression do to worn rings or valves would cost you power and fuel
economy.


Pete

wrote:
> Hello group.
>
> I've a 1999 Olds intrigue (3.5l/94K) that's been getting awful fuel
> economy for some time now and nothing seems to help. For the first year
> or so I owned it, it consistantly got 19-20mpg in all city driving. For
> the last 1.5 or so years it has dropped to 14-16mpg, usually closer to
> 14.
>
> As soon as I noticed the huge difference at the pump, I started having
> work done but nothing's changed. Thus far I've had new platinum plugs
> put in, a $180 fuel system cleaning, tires rotated and balanced and
> I've run some chevron techron thru it. I also get regular oil changes
> w/mobil1 and just had the tranny fluid changed. I check tire pressure
> often and drive pretty conservatively.
>
> People have suggested the next thing I should try is replacing the
> oxygen sensor, but both mechanics I've asked about it seem to think it
> would be a waste, and that without a check engine light it's probably
> working okay.
>
> So really I don't know what to do, but this problem is driving me nuts!
> I gotta think that something is going very wrong, but not knowing autos
> very well, or being a DIYer I have to rely on the mechanics. Is there
> some kind of diagnostic machine that can find the problem?
>
> Aside from the awful mileage problem, it's been a pretty good car. I'm
> just getting so frustrated with this that I'm thinking of trading it
> in. Thanks in advance for any suggestions!