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RAT
Dodge Dakota
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1/17/2004
17:04:57
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 Subject: RE: dealer said 180 stat will smoke the eng
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Does leaving your battery off for a couple of hour actually reset the pcm? I know you can do it in about 1 minute if you disconect the negative lead and the hold your starter on for about 20 seconds. As for high altitude I live at about 5300 feet in Payson AZ, and I have not had any problems, but I did mine in the warm summer too. That, and I'm sure that all of our trucks can very easilly be different from one another, when it comes to the way they run.
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WipLash
Dodge Dakota
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1/20/2004
20:16:14
|  RE: dealer said 180 stat will smoke the eng
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If I may interrupt, the 180 stat shouldn't cause any problems except that it will take the engine longer to warm up. Untill the temperature reaches a certain point the PCM will keep the fuel mixture rich which normally increases HP. But, this is a computer controlled vehicle and not a 1969 muscle car. The PCM will automatically cut back on ignition timing, fuel injector pulse will be shortened in duration, and the shift points will be lowered until the engine reaches the pre-programmed set point which I believe is 185 deg. Until the engine reaches this temperature you will consume more fuel and HP will actually go down because the PCM is going to cut back on all the fuel and timing parameters because it thinks it's still warming up. This is a safety feature DC programmed into the PCM to cut down on engine wear. It's part of that 6year/70K mile warranty.
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jeremiah2360
Dodge Dakota
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1/20/2004
22:24:04
| RE: dealer said 180 stat will smoke the eng
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WipLash, It`s 7/70. Engine longer to warm up? Thats the same as people thinking turning up their home thermostat will warm their house up quicker. I got on the highway a couple weeks ago when it was real cold, single digits. The engine was just beginning to warm up and wouldn`t shift into overdrive. I was worried it would trip the "running too cold too long" code as it would be running at the coldest point allowed by the 180 stat for more than 20 minutes. I think that is the limit for tripping that code. It was fine, after a few minutes the temp came up and shifted into od. I figure that if what you say is true it wouldn`t have shifted unless it`s programmed to warm up in stages. I could see an inaccurate stat causing problems, I have a Robert Shaw which are suppose to be very consistent(opens at 183 I believe).
I am curious, what was the source of your information?
03 qc 4.7 auto 4x4 25k, 20k with 180 stat
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GraphiteDak
GenIII
1/20/2004
23:53:48
| RE: dealer said 180 stat will smoke the eng
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RAT, hey I'm from Payson. I had previsoulsy lived there WAY to long and now live in West Phoenix.
My dad still lives there and for some bizarre reason my wifes family is slowly moving up there. So I'll keep making my trips about once a month or so. A month ago I took the family back on Cracker Jack road to doll baby and back out. Unfortunately I wacked a BIG ROCK going too fast thru one of the creek crossings with water in it. But no major damage and I fixed what was bent.
Like I keep saying, my 160 t-stat gave me no problems. MAYBE by NOT Having the CLUTCH FAN installed is getting mine to heat up to around 175 degrees quicker (where my electric is set to come on)?
Oh yeah. RAT, dunno how you will like it, but for sh*ts and gigles and when I had a heai up my butt I registered a website as www.paysonarizona.net
I thought of changing the domain name but it would be too much hassle
I have a mixed collection on there including the mods to my Dakota. Check it out.
.
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WipLash
Dodge Dakota
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1/21/2004
00:00:49
| RE: dealer said 180 stat will smoke the eng
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Back in 1993 I was building a CC Dakot 5.2L Auto. Brown racing cams custom made the cam shaft for me that ran good on and off the track except it didn't meet emissions. I had to have a custom PCM made for this application. Engine temp was one of the criticle parameters in the program. They changed that parameter of my program so I could run a 160 stat. Brown Racing Cams didn't do the PCM, but they had someone they knew do it. I chose them because their name was on the side of a Dakota Drag Racing Truck I saw at the drag races. I'm sure they charged me double what it was worth. It was set to always run rich mainly due to the extra overlap I ran on this cam. This helps the Magnum engine tremendously at RPM's over 5K. Just these 2 mods cost me over $2,000.00 back in 1993. It lasted 2 months and I totaled the truck. A drunk pulled out in front of me while I was blowing the cob webs out one night. This was back before Mopar Performance parts were available for the Magnum Engine. Also, places like Magnum Performance in Texas were just getting started. If you wanted performance from a Dodge back then you had to pay some one high dollars that knew what they were doing. I doubt the parameters of the program have changed much sense then. The size and shape of the PCM is different, but it still uses temp sensors, O2 sensor, TPS, Air Meters, knock sensors, crank sensors, and distance sensors to get the job done. It's just a simple program that takes all these inputs and outputs a signal to the injectors and ignition to make the engine run. That's how I know about it. I don't even know if Brown's Racing Cams is even in business anymore. I'm sure they are. Since that accident I have been absent from drag racing for the most part. I'm just now getting back into it.
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Wha?
Dodge Dakota
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1/21/2004
00:01:24
| RE: dealer said 180 stat will smoke the eng
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"Until the engine reaches this temperature you will consume more fuel and HP will actually go down because the PCM is going to cut back on all the fuel and timing parameters because it thinks it's still warming up"
Dude, put the crack pipe DOWN.
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WhipLash
Dodge Dakota
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1/21/2004
00:40:01
| RE: dealer said 180 stat will smoke the eng
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WHA?
The computer reads a voltage signal from the temperature sensor and that is how it determines the temp. You can trick the computer my soldering a resistor in line with the thermoresistor. Your temp guage will be incorrect but this will keep you from having to have your PCM "flashed". Otherwise the computer will stay in the "warm-up mode". In this mode the fuel mixture is richened and the torque convertor doesn't lock up. The torque convertor is one of the largest heat generating components in the drive train. Because the cooling lines from the transmission run through the radiator it drastically speeds up the engine warm up process by allowing the torque convertor to slip. When you drive an automatic with a locking convertor and the convertor never locks up because the engine is too cold your gas mileage drops. That's because the torque convertor slips by design (That's what allows an automatic to idle in gear). The new transmission Dodge is using on the 4.7L is servo controled. It controls the speed at which the clutch packs engage. When everything is cold it slows down the engagement of the clutchs to smooth out the shifts. Back in the early 90's Dodge was having several palnetary gear failures due to the extra HP from the 5.2L and 5.9L engines. They firmed the shifts up back then to cut back on slippage due to concerns of burning up the clutch pacs. That's when they started grenading the planetary gears. So now they have a servo controler to give a more progressive shift that starts soft and finishes firm. When you run it hard and everything is not up to temp the servo slows down the shifts to allow more slippage. This is to prevent palnetary gear failure. If creating more HP and getting better gas mileage were as simple as installing a 180 stat, DC would already have them in there.
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Floatpilot
Dodge Dakota
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1/21/2004
18:07:45
| RE: dealer said 180 stat will smoke the eng
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Wiplash.
Some of the things you are saying don't really make sense.
Just a few facts to throw at you that I have learned from aviation. Since aircraft engines are not that much different than Automotive engines, here are a couple facts. Maximum horsepower is delivered when the engine is running at peak lean mixture, which gives you a high exhaust gas ratio. This is also where the engine heats up faster than a rich mixture. One of the ways to cool down an engine if we are getting into a situation of an overheated engine is to richen the mixture as much as possible. This reduces exhaust gas temperatures, it does reduce engine temperature, and it will produce less power. Only so much fuel will burn with a certain amount of air. The rest is exhausted away. The aircraft I am flying right now in the very cold air is using more fuel because of the density of the air (20Gals/hour compared to 17Gals/hour in summer). We are at a 700ft elevation above sea level, and with the temperature of -30C the aircraft is performing as if it were at roughly 1000 feet below sea level. There is more air going into the engine because of the cold, compared to a +30 day. Thats why you use more fuel. With a cold engine, some of the energy from combustion is wasted to heat loss to the metal, which affects power output.
I have no idea how the dakota computer works, I would like to learn, but what you are saying kinda goes against optimizing engine performance and operation.
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WipLash
Dodge Dakota
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1/21/2004
19:18:36
| RE: dealer said 180 stat will smoke the eng
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FloatPilot,
You are exactly right. That is why I always ask for numbers. I can show with mathmatics that horsepower goes down as the engine temp goes down. It is a simple equation. HP is a direct result of the combustion process. Heat is generated when you burn fuel. The more HP you make the more heat you generate. You can actually calculate engine HP by taking the incoming air temperature at a given RPM and the out going exhaust temperature. Then you have to know how much air is being consumed via an air flow meter or a peto-tube. The higher the exhaust temp and the lower the incoming air temp the more HP. The less fuel you can consume and the more air you can consume and still maintain the same incoming and exhausting air temperatures the more HP you make.
I think the only reason people might see a HP gain with a 180 or 160 stat is the fact that the PCM richens the air/fuel ratio while in the warm-up mode. If they are having detenation problems this could fix that problem. In other words they are fixing one problem by creating another problem. I recomend running a colder spark plug if you are detenating.
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GraphiteDak
GenIII
1/21/2004
22:58:48
| RE: dealer said 180 stat will smoke the eng
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People have been dropping in colder t-stats for years, even before fuel injection. I always ran a 170 or so in my older 302 Fords and 350 Chevy's and the likes. No problems. Especially on those engines, the water jacket went thru the intake manifold to HEAT it up. I think the only reason the factory installs 195 t-stats is to make these damn things work in all 50 states and all climates. But me living in Phoenix I don't need no t-stat that also makes the Dak stay warm and toasty for people living in New York or some place that stays below zero for months out of every year.
The 4.7's are a smart design buy using a plastic intake that is not heated and does not conduct much heat from the engine.
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Duner
Dodge Dakota
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1/22/2004
02:34:06
| same old story
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Another issue that's related to engine operating temp - is the heat of the fuel rail and it's fuel. Did you ever notice how responsive the engine is when you first start out and it's still cool? When the engine is cool, so is the fuel rail and also the fuel inside that rail. As the engine gets hot the fuel rail gets hot also. Then the fuel gets hot.
When the fuel gets hot it's density changes. Fuel expands at a basic rate of 3.5% per 50 degrees. The problem is that not all of the fuel is heating evenly in the fuel rail. The modern Dodge engines have a returnless fuel rail system. Fuel comes into the fuel rail on the driver's side and dead ends on the passenger side. When the engine is hot - the longer the fuel sits in the fuel rail the hotter it gets. The cylinders on the driver's side keep getting new fresh and cool fuel (ambient temp). Cylinders and injectors #6 and #8 only get the fuel after it's heated up completely. On a hot day this fuel can get in excess of 300 degrees in that fuel rail. Luckily it's under pressure or it would boil and vaporize immediately. So we have 300 degree fuel on the passenger side and ambient temp fuel at some of the cylinders on the driver's side. If we decide that the original ambient temp of the fuel is 100 degrees, then we have a 200 degree difference. That difference in temps will lead to as much as a 14% difference in density's of the fuel. That relates to a 14% difference in jetting as a final result. The outcome is the equivelant of roughly 16# injectors on the #6 and #8 cylinders, 19#ers on the #3 and #5 cylinders, and somewhere between those # for the rest of the cylinders. How well would you expect this engine to run with different size injectors for the cylinders? It sounds like it would be pretty unbalanced doesn't it? That's the end result. That's the HP loss and sluggishness you feel when the engine is hot.
A cooler thermostat helps to delay this heat soak of the engine. A lower engine operating temp will also help lower this max fuel rail temp by some percentage - which helps reduce the differences seen (and felt) in fuel density between cylinders. I suspect that this is what most people get out of the cooler thermostat.
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WipLash
Dodge Dakota
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1/22/2004
08:35:45
| RE: dealer said 180 stat will smoke the eng
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You need to read the brand new thread posted yesterday by by a gut in FLORIDA that just installed a new stat. Since he changed the stat his PCM keeps throwing the code for taking too long to warm up and his check engine light comes on.
Also, the older cars your referring to didn't have computers controling the ignition timing and the fuel delivery. Until the engine reaches a certain temperature the computer cuts back on both the fuel delivery and the ignition timing.
The reason the factory installs 195's instead of 180's or 160's is because 195 is about as cool as you can run the engine and still get the moisture out of the crankcase. Everytime your engine heats up and cools down there is a process called CONDENSATION that takes place. This condinsations gets in your oil. When it combines with the unburned fuel and other hydrocarbons that get past the rings it forms acid. This acid destroys the soft metal your rod and main bearings are made of. If increasing HP and engine life were as simple as installing a 180 stat I think DC, Chevy, Ford, and all the other manufactures of the world would already have them in there.
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RAT
Dodge Dakota
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1/23/2004
10:43:48
|  RE: dealer said 180 stat will smoke the eng
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Hey GraphiteDak That's crazy. I've seen the yello car on you websites homepage around town about a million times here in Payson. But he finnally took the spoiler off now. I'm pretty sure he has no other usefull mods, cause I burned the crap out of him a couple of time now. That's not saying much when I only have a lightly modded 2.5L. But it's nice to hear from somone that can relate to the black hole that is Payson. LOL. Phoenix, is nice to drive in. Makes my truck a whole lot faster with the richer air. See you around porbably. I drive an Intense Blue reg cab with a broken right tail light for now.
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TexasTodd
Dodge Dakota
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1/23/2004
11:54:19
| RE: dealer said 180 stat will smoke the eng
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Duner,
All I've got to say is,
Could you find time to post here more often.
We're not worthy!!! (No sarcasm intended)
Todd Bouton
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