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Discussion Starter · #1 ·
I have an 04' with the 3l Duratec DOHC engine and was wondering what kind of normal operating I should be seeing with a scan tool. I looked up the thermostat temp and it's supposed to be 188, however, when I'm driving it will only warm up to about 174 when driving. If I stop at a light for a while it'll go up to 195-200 but when I start driving again it drops back down to 178-180. My question is do you think my thermostat is opening to early or has the wrong thermostat in it? I know that a warmer engine will be better fuel efficiency.

I noticed this because I went to smog my car yesterday(again because I tried in the past but had to park it because I haven't had time to work on it) and it fails because of high hydrocarbons at idle. I told the guy about it seeming to run cooler than I thought it should and he said it may have something to do with it because it will run richer when it's cooler.

Thanks in advance.
 

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Normally I wouldn't worry about it terribly much, but since you need your car smogged and winter is approaching, I guess you need to fix it. Your thermostat is probably stuck open and has to be replaced. Especially so if your car takes more than about 5 minutes of driving to reach full temp. Once the car is warmed up the temp gauge should stay roughly centered and shouldn't change if you speed up or stop. The engine runs richer when cold, so if your engine isn't fully warm, you will have higher HC emissions.

Easy enough to replace it yourself. Read: http://www.taurusclub.com/forum/82-maintenance-repair/147304-replacing-thermostat-2000-duratec.html
 

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1st verify you have a Motorcraft thermostat. If you do verify it opens and closes correctly in hot water. I have a '97 Duratec and I believe it is wide open at 192F. I would consider 192F to 197F a normal operating range. My temp gauge is at 1/3 scale with these temps.

And your right about the engine being cooler and using more fuel. Verify temps with a scan tool if you can.

Monsoon
 

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Discussion Starter · #4 ·
Maybe I wasn't clear, what I meant by "what kind of normal operating I should be seeing with a scan tool" and then stated exact temps was that those were the temps I was getting with a scan tool. My bad if there was confusion because I was unclear in my first post.

Are you guys saying that I should be seeing temps in the 192-197 range when fully warmed up and they shouldn't cool bad down?
 

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Maybe I wasn't clear, what I meant by "what kind of normal operating I should be seeing with a scan tool" and then stated exact temps was that those were the temps I was getting with a scan tool. My bad if there was confusion because I was unclear in my first post.

Are you guys saying that I should be seeing temps in the 192-197 range when fully warmed up and they shouldn't cool bad down?
Added pic from CarChip. (recorder)

Temp should come up to ~195 and stay there.

Thermostat is one thing, air dam is another.

-chart-
 

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I've got an 04 DOHC and it reads 187 degrees and climbs a bit in traffic.

Passes smog with flying colours.

Idle limit is 150ppm and my reading is 6ppm.

Original plugs 134,000 kms(83,750 miles)

I'd be looking elsewhere for your high hydrocarbon readings.
 

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Added pic from CarChip. (recorder)

Temp should come up to ~195 and stay there.

Thermostat is one thing, air dam is another.

-chart-

You'll note on his graph nothing is above 200F. You may reach 200F on an extreme day.

Monsoon
 

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Mine goes higher in slow traffic and hot days - if I have the A/C off.
In my experience, the Motorcraft thermostat for 1996 has a lower temperature than the one it is sold by others. Mine RT-1104 was stamped 88C (190F).

Personally, after I did replace the thermostat, I did replace also the temperature sensor (the one for PCM, is different from the gauge one).
For the rich mixture - I would start with the O2 sensors. Especially if you are over 120k miles.
 

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Mine goes higher in slow traffic and hot days - if I have the A/C off.
In my experience, the Motorcraft thermostat for 1996 has a lower temperature than the one it is sold by others. Mine RT-1104 was stamped 88C (190F).

Personally, after I did replace the thermostat, I did replace also the temperature sensor (the one for PCM, is different from the gauge one).
For the rich mixture - I would start with the O2 sensors. Especially if you are over 120k miles.
You never know when maintence (or lack of) makes things not work to prime. I had high positive fuel trims on my Lin Cont but it ran fine. Routine fuel filter replaced and according to my last trip and recorded by CarChip it is just a tick positve, maybe average +3.

So one might imagine, air filter, PCV and hoses, vacuum leaks and such all making things run out of whack and the system trying to cover it up.

-chart-
 

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Discussion Starter · #10 ·
Maybe I need to write the history since I've had the car.

I bought the car with a misfire on the front bank middle cylinder(#5?). Turned out to be just a chewed wire. Fixed wire and the problem went away. I believe my cat is bad because of this but want to fix everything else before getting drastic and replacing that.

Things I've replaced. Fuel filter, Air filter, Spark plugs, PCV valve, both pre-cat O2 sensors(bosch brand), and front bank(2?) post cat sensor(also bosch). I say bosch because I'm not a fan of them but it's all the local napa had in stock. Changed the engine oil and filter.

I've also cleaned the MAF sensor(with MAF clearer from CRC), and checked for vacuum leaks with brake clean(found nothing). I wanted to check the fuel pressure but couldn't find the test port, perhaps it's behind the wheel well?

When I first got it first thing I did was fix the bad wire then I pured some injector cleaner and put in some 91 gas from shell before I did any of the of maintenance items.

When I first went to take the car in for some I hadn't replaced the spark plugs yet. I remember that it failed because the HC was 240 or something near that at idle and the tech said it was almost a gross polluter. He said change the plugs and put a tank of 89 Chevron with techron in, run the tank nearly dry and come back. I did and I put a little bit of denatured alcohol in and my HC went to 178 at idle. My 2500rpm test passes just fine. I don't have all the numbers from the first test but here's what I have from the second at idle;

HC = 178 ppm
NO = 0 ppm
CO = 0.29%(tech said was high but passable)
CO2 = 13.9%
O2 = 0.6%

I have a scan tool and I have an SCT x2 that I should be able to use to data-log if anyone wants me to and would be willing to look at it. Just tell me what you want logged and I'll log it on my 15 minute drive to work.
 

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Bosh are the original O2 sensors on our Fords.
Looks like you are not burning the whole fuel and still have O2 left, so it is not a rich mixture.
What spark plugs do you have now? If they are cheap ones, put some Autolite Iridium XP in...
What is the temperature indicated by PCM (not the gauge, different sensors)? With O2 sensors new - does it go on closed loop or stays in open loop? If the PCM sensor does not indicate the right temperature, PCM will not go in closed loop and you will fail emissions.
 

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Discussion Starter · #12 · (Edited)
Bosh are the original O2 sensors on our Fords.
Looks like you are not burning the whole fuel and still have O2 left, so it is not a rich mixture.
What spark plugs do you have now? If they are cheap ones, put some Autolite Iridium XP in...
What is the temperature indicated by PCM (not the gauge, different sensors)? With O2 sensors new - does it go on closed loop or stays in open loop? If the PCM sensor does not indicate the right temperature, PCM will not go in closed loop and you will fail emissions.
My lincoln LS came it NTK oxygen sensors from the factory and that's what I took off the taurus.

I have NGK G-power platinums. I was thinking of going autolite coppers as copper is the best conductor.

As stated in the first post "when I'm driving it will only warm up to about 174 when driving. If I stop at a light for a while it'll go up to 195-200 but when I start driving again it drops back down to 178-180." That's what my scan tool says. The gauge stays in the middle but doesn't seem to accurately display temperature in a linear fashion.

My scan tool says it's in closed loop. It seemed to me that it entered closed loop rather early but I wasn't paying a whole lot of attention to it at first.
 

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No, the conductivity does not matter (the wires have more resistance in them). What maters is errosion in time and the size of the tip (influences the electric field value).
The fine tip platinum/iridium with the ground electrode having iridium point is the best for ignition. Iridium is better for errosion.
NGK G-Power are fine tip also (but only platinum and no ground iridium bump), I am not sure of the temperature range, that's why I did recomend Autolites - they are making the Ford OE ones. XP104.
NGK are fine for rice burners...
The O2 sensor in my 96 Sable and 01 Explorer where Bosch - but both are older than 2004. It should not matter that much anyway.
 

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Discussion Starter · #14 ·
No, the conductivity does not matter (the wires have more resistance in them). What maters is errosion in time and the size of the tip (influences the electric field value).
The fine tip platinum/iridium with the ground electrode having iridium point is the best for ignition. Iridium is better for errosion.
NGK G-Power are fine tip also (but only platinum and no ground iridium bump), I am not sure of the temperature range, that's why I did recomend Autolites - they are making the Ford OE ones.

The O2 sensor in my 96 Sable and 01 Explorer where Bosch - but both are older than 2004. It should not matter that much anyway.
One question, what wires? My taurus has COP design, there's a spring in there, is that what you mean?
 

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My lincoln LS came it NTK oxygen sensors from the factory and that's what I took off the taurus.

I have NGK G-power platinums. I was thinking of going autolite coppers as copper is the best conductor.

As stated in the first post "when I'm driving it will only warm up to about 174 when driving. If I stop at a light for a while it'll go up to 195-200 but when I start driving again it drops back down to 178-180." That's what my scan tool says. The gauge stays in the middle but doesn't seem to accurately display temperature in a linear fashion.

My scan tool says it's in closed loop. It seemed to me that it entered closed loop rather early but I wasn't paying a whole lot of attention to it at first.

"I start driving again it drops back down to 178-180."

That is hot enough for close loop but not for good mpg. The thermostat should keep it at temp (~195) while driving, and the fans should keep it under 212 or so while sitting. Mine are Sables and have a bit larger grille opening so that makes a difference. I think your thermostat is not good.

Temp should come up fast and lock in and hold no matter what the outside temp.

-chart-
 

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One question, what wires? My taurus has COP design, there's a spring in there, is that what you mean?
The internal wiring in the COP has a resistor for RF noise canceling, some 10kohms. So it does not matter that the plug has copper in it (they all have internal copper wiring) or on the tip (platinum, iridium, copper - all the tips will have some miliohms resistance).
Fine tip matters more for complete burning. Temperature range matters also for emissions.
 

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The internal wiring in the COP has a resistor for RF noise canceling, some 10kohms. So it does not matter that the plug has copper in it (they all have internal copper wiring) or on the tip (platinum, iridium, copper - all the tips will have some miliohms resistance).
Fine tip matters more for complete burning. Temperature range matters also for emissions.
Plug temp range is largely a thing of the past with modern fine wire platinum +.

The insulator temp kept the large steel wire plugs cool enough to not burn up but not so cool that carbon bilt up on the insulator and shorted it out.

Fine wire platinum + gets really hot but does not burn up, so the insulator can run hot and clean. Major technology imporvement.

Really good plugs are cheap compared to the labor and hassle of putting them in. (AutoLite XP for me) all 3 cars.

-chart-
 

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I disagree, temperature range is still as important as ever.
No, the fine tip is not hotter. If the tip would be HOTTER, then the fuel will ignite BEFORE the right time, just by being in contact with the tip.
The temperature range is important maily for the insolator. If the isolator is not warm enough, then deposits can form and short-circuit the tip.
Also, if insolator is too hot, it does not cool enough the tip and premature errosion and ingnition can start.
Fine tip was developed because, for the same voltage, the smaller tip creates a higher intensity electric field, and THAT field is what generates the spark (not the voltage itself).
 

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Maybe I need to write the history since I've had the car.

I bought the car with a misfire on the front bank middle cylinder(#5?). Turned out to be just a chewed wire. Fixed wire and the problem went away. I believe my cat is bad because of this but want to fix everything else before getting drastic and replacing that.

Things I've replaced. Fuel filter, Air filter, Spark plugs, PCV valve, both pre-cat O2 sensors(bosch brand), and front bank(2?) post cat sensor(also bosch). I say bosch because I'm not a fan of them but it's all the local napa had in stock. Changed the engine oil and filter.

I've also cleaned the MAF sensor(with MAF clearer from CRC), and checked for vacuum leaks with brake clean(found nothing). I wanted to check the fuel pressure but couldn't find the test port, perhaps it's behind the wheel well?

When I first got it first thing I did was fix the bad wire then I pured some injector cleaner and put in some 91 gas from shell before I did any of the of maintenance items.

When I first went to take the car in for some I hadn't replaced the spark plugs yet. I remember that it failed because the HC was 240 or something near that at idle and the tech said it was almost a gross polluter. He said change the plugs and put a tank of 89 Chevron with techron in, run the tank nearly dry and come back. I did and I put a little bit of denatured alcohol in and my HC went to 178 at idle. My 2500rpm test passes just fine. I don't have all the numbers from the first test but here's what I have from the second at idle;

HC = 178 ppm
NO = 0 ppm
CO = 0.29%(tech said was high but passable)
CO2 = 13.9%
O2 = 0.6%

I have a scan tool and I have an SCT x2 that I should be able to use to data-log if anyone wants me to and would be willing to look at it. Just tell me what you want logged and I'll log it on my 15 minute drive to work.
I would have never put Bosch O2 sensors in. You don't know if the Bosch O2 sensors works and plays well with the rest of the system. There could be a huge incompatibility here and you will never know it. I put all new Motorcraft O2 sensors in around 120K miles and haven't had a check engine light and passes emissions with flying colors.

If your Bosch O2 sensors are feeding the PCM bogus data this may explain why your HCs are high. O2 sensors are critical pieces to the puzzle to having your engine run correctly. I would recommend Motorcraft thermostat and Motorcraft O2 sensors and then retest.

Your emission check should look something like this:
http://www.taurusclub.com/forum/82-maintenance-repair/165585-sable-emission-specs-1997-duratec.html
Note: How low the HC readings are. Even with plugs that have over a 100K miles.

Monsoon
 

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On a day like today, 55-60F w/low humidity near sea level, my car was running around 184F on the ScanGauge cruising at 60mph continuously for 2 hrs. This past summer it got up to 200F when I had the AC cranked, doing 75-80 in Detroit when it was 100F outside.
 
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