Pontiac: 180 degree thermostat

If you replace the Intake manifold with the newly redesigned ( in 1999 )
one, the car should be alright then and shouldn't need a lower degree
thermostat.

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Harryface
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1991 Pontiac Bonneville LE, 3800 V6
_~_~_~_~275,982 miles_~_~_ ~_~_

Keep the OEM. 180's a worthless.

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"gooch" <com> wrote in message
news:talkaboutautos.com... 
after I fix the upper plenum and lower intake coolant leak (great design GM,
jacka%@). My question is I have always heard with the computer controlled
cars that the thermostat is critical to gas mileage because at 180 the
computer still thinks the engine is not fully warmed up therefore, it
increases the fuel to the cylinders because like we all know a cold engine
requires my fuel to make the same power. Is this still the case with the obd
II or was it just with the earlier cars? 

why is it worthless?
I put one in my bonnie and it runs fine.

"98 Camaro" <net> wrote in message
news:supernews.com... 
GM, 
obd 

You waste more fuel and put out higher emissions running a 180 tstat.

In article <_ZcQb.36345$nyroc.rr.com>, mlawson1
@twcny.rr.com says... 

Why would OBD II be any different? If anything it would be more
sensitive to those changes.

It runs fine, but what good does it do, very little if anything at all. All
it does is make your ECM think that your car is not all the way heated, all
of the time. Thus burns more fuel, all the time. You want to add fuel to
your mix, hit the accelerator, or find a way to add more air density (ie
cold air) and/or volume (ie cold air intake or air induction).


"Mike" <rr.com> wrote in message
news:_ZcQb.36345$nyroc.rr.com... 
controlled 
engine 

They are all alike, in that the car won't go closed loop until fully warmed
up. I don't know what temperature your car uses, but I did have one factory
shop manual that actually gave a number. It was 90C, which is 194F.

"gooch" <com> wrote in message
news:talkaboutautos.com... 
after I fix the upper plenum and lower intake coolant leak (great design GM,
jacka%@). My question is I have always heard with the computer controlled
cars that the thermostat is critical to gas mileage because at 180 the
computer still thinks the engine is not fully warmed up therefore, it
increases the fuel to the cylinders because like we all know a cold engine
requires my fuel to make the same power. Is this still the case with the obd
II or was it just with the earlier cars? 

"Joe" wrote
 
warmed 
factory 

I'd like to see that manual. I think that folks give
out some incorrect info on when the vehicle goes
into closed loop. It's much quicker then you think.

For example, on the original posters car, (using
a 98 manual, as the manuals I have access to don't
go back further then 98), the temp at which the
engine will go into closed loop is 20C/68F. In other
words, a 180 degree thermostat will have no bearing
on whether the engine goes into closed loop, as the
engine should go into closed loop way before 180 degrees
is achieved.

Still, you achieve nothing by using a 180 degree thermostat,
and in the case of the OP's car, lower coolant temperature
has "nothing" to do with the intake manifold design problem.
It won't help the problem, as the problem is not related
to coolant temps but to EGR gas temps coming up from
the lower manifold up thru the plastic manifold.

But of course, myths will persist.

Ian

Actually the computer will fall back on a time delay if proper temperature hasen't been reached by that time. It won't continue to add fuel all day in a futile attmept to warm the engine up. What is beneficial is if you have a supercharger the lower temperatures will allow the PCM to have maximum spark advance which might get you a little more power. Most who go with a 180t-stat will opt for the drilled stat. It has 4 small holes drilled in the housing which allow a small amount of coolant to constantly blow past it. This is available from www.zzperformance.com as well as other Bonneville performance websites.