I have a 1994 Taurus wagon with a 3.8 V6, the car runs fine, well it did
until now. We took a trip out of town, the trip took about 1.5 hours,
(almost all freeway, averaged 60 mph on cruise) and ended with a long upward
hill. When we stopped at a gas station the car would not idle properly, ran
rough, and then stalled. After about 15 minutes the car started and ran ok,
we were at our destination so we parked for the night. The next day the car
started and ran like normal so we returned home, the car again after about
1.5 hours of freeway driving started to act up, first the check engine light
start coming on, then going out, as well as noticeable power loss when
trying to accelerate.
When we pulled off the freeway and the car stalled at the first stop sign.
We were able to inch the car home, each time stopping for about 10 minutes
or until the car would start and run to the next stop sign or light.
Now I am confused, a friend told me that it may be the catalytic converter,
how and why? these parts are very expensive, I do not want to go about
trying to fix this problem with a trial and error approach.
I have only owned the car for the last 6 months and have no maintenance
I thank anyone who responds to my post, as I would like to know something
before I have to take it in to the dealership.
Neil.... no one in their right mind will respond by email now that we've seen
people post on here just to gather good email addresses...
sorry, blame spammers!
And as said... you can just find any web-capable PC and look it up on google
Teknical opined in
- Yes, I'm a crusty old geezer curmudgeon.. deal with it! -
It could be overheating.
I had the same problem when I forgot to put coolant back in my old 289 after
putting a different pair of heads on it. The heads had large chambers so
compression was lower and I expected power to be lower. So I ran the car for
a week with virtually no coolant. The overheat light never triggered because
I accidentally broke the sender (it was a bad day). Anyhow, running on teh
highway it was gutless. Stopping for a toll booth it stalled and didn't
wanna start. Took me a minute to get it started again and then it ran
alright once I got moving again. Finally I remembered I forgot to fill the
coolant system so I pulled over and filled it. Problem solved. More power
and didn't run rough or stall. Of course I had gone a few hundred miles with
no coolant already, but no harm was done. Those 289s sure are tough little
So, make sure your coolant system is full and your thermostat is working.
Also, you may wanna check that your temp sensor is working and your overheat
light bulb is not burnt out or otherwise non-functional.
An engine can overheat for several reasons other than that, such as retarded
timing, malfunctioning fan, malfunctioning EGR valve, I suppose O2 sensors
could cause it as well.
Anyhow, it's just something that may be worth checking.
I believe you are the resident troll, but I don't recall so I'll explain
anyway. A malfuctioning EGR system can lean out the mixture. A
malfunctioning O2 sensor may result in giving an false rich reading, the
computer will compensate by leaning out the mixture. A leaner mixture burns
hotter, raising combustion chamber temps and thus the temperature of the
entire engine. Also, an excessively lean mixture can burn holes in pistons
and do some real nasty damage.
A malfunctioning EGR valve can not add any exhaust gas. I didn't say _how_
it was malfunctioning, just that it was...
Interesting. How do you know this? Where did you read it, or more
importantly, where can I read it? How about this hypothetical situation in
which the O2 sensors are reading rather rich when the mixture is in fact
just fine. What does the computer do? What does it do when the mixture leans
to the point that it starts pinging and it cuts back on timing as the knock
sensors tell it the engine is suffering pre-detonation? A lean mixture and
retarded timing will certainly cause higher engine temps, and retarded
timing can easily overheat an engine.
The job of the EGR is to PUT EXHAUST into the intake air. That is how ERG
functions. By introducing a non-combustible gas into the intake it lowers
combustion temperatures. An EGR will only fail in two ways open or closed. If
it fails open? The combustion process is greatly impeded because the oxygen
content of the intake air is reduced. It is not a lean mixture, the ratio of
fuel to gas is the same, the only change is the composition of the gas, it's now
more inert. That is how NOX is controlled. It was by accident that engineers
found it also helped with knock, a nice side effect. Stuck closed? The engine
will not over heat, might have some mild ping under load, most likely not enough
to cause damage if all other systems are ok.
That will cost you, it's called class room training. You can also buy materials
to learn what is going on.
That will not happen. Because of all the variables it is impossible to have a
mixture that is just fine, as a result of this fact the ECM uses the O2's to
determine if the mixture is too rich or lean. Typically the O2 when failing
does not respond; the voltage signal says constant. That alone is enough to
cause the ECM too know there is something amiss. When the ECM has an O2 that
does not switch, it try's to make it switch to test it.
First off not all engines have knock sensors, second the ones that do; do not
work in the way you are implying. When the ECM sees a signal from the knock
sensor it only retards the timing a few degrees at most, it does not keep going
until it does not see the signal any more.
This is not a race engine we are talking about, this is a production engine with
the average compression ratios of 9:1 at the most for high performance engines,
most are in the range of 8:1. The only thing that is going to happen is low
power, lean mixtures are the result of not enough fuel volume which causes low
pressure under load.
Intersting. How will a lean mixture burn colder? Car engines run richer that
stoicheometric. Stoich is quite 'lean' for automotice engien standards and
will burn too hot, causing damage to parts. I'm curious, if you are correct
in that fuel injected engines running the same lean mixture as a carbureted
engine will burn colder than a carbureted engine, please explain how that
is. Leaner burns hotter, the flame front on the cylinder does not 'see' the
fuel inject or carb. All it 'sees' is the air/fuel ratio, so how the air and
fuel were mixed is irrelevant, or at elast should be as far as anything I
was ever tought. Anyhow, please elaborate and explain how an engine running
a relatively lean mixture will run colder with fuel injection than it would
with a carburetor delivering that same mixture.
Wrong! That is true with a carbureted engine, but the opposite
happens with a fuel injected engine.
And you are talking about a Taurus, not a 289/302.
To the original poster, have you tried a new TFI module?
That sounds good on paper but it's not really true in the real world. Think
in terms of really bad efficiency, throttle at 50 or 75% just to maintain
speed and the trans will probably be in 2nd or 3rd instead of OD. Soon
things are smoking hot.
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