| From | Message |
Sephiroth
Dodge Dakota
JOIN HERE
2/28/2004
23:22:31
|
 Subject: Fuel Mixture Changes?
IP: Logged
Message:
I had a thought today that may increase my mileage a little. I run a 180deg thermo and the orange coolant now. The truck temperature guage goes just BARELY past the safe run mark (it isn't in the choke range, but it's much cooler than before, about 1/4 of the way up), so I was curious if it would be safe to lean the mixture a hair. I have no clue what the Dakota's default mixture is, but I've heard that 14.7 air to 1 gas is the ideal fuel economy mixture, and about 16.1 air to 1 gas is about the max safe mixture. I have a '95 Dak 4x4 with a 5.2L V8. If it is safe to lean it a little, I wouldn't DARE try beyond 15.0, but I am assuming I'd need my computer programmed to change the mixture? Anybody have any input on this? If it would work, I think it'd be kind of cool. I know I don't want the heat in the chambers to go up too high, but I'm kind of gray on the mixture versus heat area.
|
WipLash
R/T
2/29/2004
00:02:50
|  RE: Fuel Mixture Changes?
IP: Logged
Message:
Sephiroth,
If you can find someone to recalibrate your PCM to run leaner, let me know.......
It was common 20 years ago to run 16:1. The reason we don't now is the EPA. They claim NOX emissions (ozone depleting) go up when you increase the air/fuel ratio. 16:1 won't hurt your engine.
|
Sephiroth
Dodge Dakota
JOIN HERE
2/29/2004
11:15:53
| RE: Fuel Mixture Changes?
IP: Logged
Message:
You positive that hgh won't damage it? Mind you, I plan on giving this thing to my kids one day when it has 500k on it. I do know that leaner mixtures mean higher temps, and while the coolant-system cools the block over-all, inside the actual chamber still worries me. I've heard horror stories of guys who leaned them too far and either ruined their engines fast, or the first time they stomped it, had the engine blow on them. I'm not rich by far, and can't afford a new engine!
|
WipLash
R/T
2/29/2004
12:00:53
| RE: Fuel Mixture Changes?
IP: Logged
Message:
16:1 is relatively conservative on the lean side. That's only 1.3 over the 14.7:1. I was running my 68 Big Block Charger at 18:1 at cruising (high vacuum) conditions. With fuel injection you run in closed loop most of the time so even at part throttle you will be running lean. With the carb on my 68, the vacuum fell at patr throttle conditions enough for the fuel richening circuit to kick in so I didn't have labor knock. At wide open throttle you will still be getting about 12:1 on the MPI system. You might labor knock at part throttle when the engine is hot and your under a heavy load. Hughes sells a knock sensor kit that will cut back timing on Dodges MPI system if your that worried about it. Then you could run even leaner like 16.5:1 or possibly even 17:1.
|
Sephiroth
Dodge Dakota
JOIN HERE
2/29/2004
20:24:03
| RE: Fuel Mixture Changes?
IP: Logged
Message:
Thanks for the info! My friend John is testing this first. We're dropping a 180deg thermo into his '01 Corvette with the LS1 engine. He has something on a laptop called 'LS1Edit' to set things like that. He's going to lean his after we super-cool it and then do a few tests on the road and in the city to see the MPG difference. If it is worth me paying to have mine changed, I'll do it and post the results. I just think it'd be cool because then I'd get better mileage on a 5.2 than most people. As it is I get DAMN good mileage with the basic mods I have now. Plus, the engine is running cooler than normal and warming it up a little to gain a few miles shouldn't hurt too badly. Thanks again for the info!
|
WipLash
R/T
2/29/2004
22:44:01
| RE: Fuel Mixture Changes?
IP: Logged
Message:
Doesn't it just suck that the Chevy guys have these sort of tools to work with and we don't? He can do this with an 01vet? I knew stuff like that had been out for the older Chevys. They were advertising lap top software and hardware as early as 1994 for Chevys. I thought all the OBD2 stuff was pretty much unaccessable unless your a hacker. Sometimes I wonder what keeps me driving a Dodge.
|
Deerridge
GenIII
3/01/2004
13:14:55
|  RE: Fuel Mixture Changes?
IP: Logged
Message:
I've got a local guy here in Jonesborough, TN who changes mine with some sort of $5000 flash device. I assumed it was rather common. He made a noticable differance in horse power/acceleration before and after (a couple of tenths 0-60, G-tech). I know he changed the fuel/air ratio and the timing. I'm guessing he got me an extra 10hp. The G-tech readings are way to wild to tell (171 to 350Hp). The 0-60 should be right though.
Real Horsepower
|
Sephiroth
Dodge Dakota
JOIN HERE
3/01/2004
13:57:55
|  RE: Fuel Mixture Changes?
IP: Logged
Message:
In that case, afetr he changed it, did your engine change in temperatures or sounds? I'm anxious to do this, but am also abit nervous about it since the idea of welding my pistons to the cylinder-walls does NOT sound good! My brother did that in an old go-cart by riding it all day straight without stopping longer than to fuel up. He also went through a few clutches, hehe!
|
deerridge
GenIII
3/01/2004
14:11:33
| RE: Fuel Mixture Changes?
IP: Logged
Message:
No noticeable change in the temperature only a little higer scream at full throttle. I have Gibson headers and Int perf Gen II Intake on mine. I'm after pulling torque and its way over stock now at low RPM. The gas milage is the same to slightly improved.
Real Horsepower
|
WipLash
R/T
3/01/2004
19:08:39
| RE: Fuel Mixture Changes?
IP: Logged
Message:
Deerridge,
This guy is flashing your 2002 4.7L? Please tell me no... I just sold my 2002 4.7L. One of the deciding factors for me selling the 4.7L instead of my 5.9L was for the reason that I couldn't find anyone that could flash the 2002 PCM.
Anyway, can you give out this guy's name and/or number? Does he have a shop? I would like to see him do some magic on my 2000 R/T's PCM.
I'm at the other end of TN.
|
.boB
Dodge Dakota
JOIN HERE
3/01/2004
20:36:48
| RE: Fuel Mixture Changes?
IP: Logged
Message:
Setting fuel mixture is a complicated process. It requires a programmable computer and a dyno. 16-17:1 is fine at part throttle cruise, but way too lean under a load. Basic fuel mixture depends on a combination of air temperature, coolant/head/engine temperature, throttle position, barometric pressure, and engine load. If you want to get fancy, other parameters can also be included.
Closed loop should not be adjusting the trim more than 20%. And closed loop operation is disabled at somewhere around 75% throttle/load.
Finding someone who has all the right equipment and the experiance to use it is a little difficult. They are out there, but hard to find. And it's expensive. If your goal is improved fel mileage to save money, you better sit down and do the math before spending any money. A good custom chip will cost you $1,000 - $1500, depending. That will buy a lot of fuel. You'de probably have to drive around 200,000 miles to recoup the cost.
|
WipLash
R/T
3/01/2004
21:10:01
| RE: Fuel Mixture Changes?
IP: Logged
Message:
I'm going to hook up my $50.00 air/fuel ratio meter and check my current readings before I do anything. I can't imagine this thing running at 14.7:1 and only getting 12mpg. I'm also going to do a compression check. My 95 CC RAM had the same 5.9L engine, weighed 800lbs more, and got 16mpg on the interstate at 75mph. I can't get 12. I was getting between 15-17mpg just a few months ago. My 98 R/T got 17mpg on a regular basis at 70-75mph. It average 15mpg. I'm barely averaging 12.
Also, I ran 18:1 for 5 years in my Charger (92-97) with no problems. Of course, it was carberated and I had the power circuit running 12:1. Part throttle fluctuated between 13:1 and 17:1 depending on engine RPM's and how far you opened the throttle blades.
At 16:1, if you experience overheating (not likely) or detonation (highly possible), all you have to do is cut back on the timing. There was a thread posted a few weeks ago that detailed the modifications you could do to the factory crank sensor to reduce or advance the timing.
Chrysler was running engines leaner than 16.5:1 back in the late 70's. Ever heard of the "LEAN BURN SYTEM" (1976)? That's probably before most of ya's time.
|
Sephiroth
Dodge Dakota
JOIN HERE
3/02/2004
00:06:58
| RE: Fuel Mixture Changes?
IP: Logged
Message:
I was born in '80, so yeah. However, I was thinking that when a person changed the fuel/air mixture, they also adjusted timing. I wish I could afford the programmer for my truck, but I'm not that rich yet.
Also after doing some research, I've begun to ponder heating my fuel before it hits the chamber. Would this be a good idea? I could easily extend my fuel-line and have it wrap around the manifold a few times before going into the engine. It should make it more combustible. Thing is, I've heard rumors (seen no facts) that while doing such a thing improves mileage, it can decrease power?! Any input on this one?
|
WipLash
R/T
3/02/2004
00:53:54
| RE: Fuel Mixture Changes?
IP: Logged
Message:
Sephiroth,
I'm not sure if your serious, but here it goes....
While hotter air/fuel is less dense and would require less fuel (more air) to burn, I really don't think you should try that. Just the thought of HEATING gasoline sends chills down my spine. In theory, what you said is correct. Prior to MPI they actually heated the bottom of the intake with exhaust gass (heat cross-over) to accomplish the same thing. The heat X-over super-heated the incoming air/fuel and vaporised it. This helped the engine run more efficient, but it KILLED hp.
I highly advise that you not try this. I would stick to the reprogramming.
|
j
GenIII
3/02/2004
10:53:55
| RE: Fuel Mixture Changes?
IP: Logged
Message:
I don't think you can adjust the timing on the 4.7. (unless you do it by flashing the computer).
2000 4.7 CC auto, clear corners, Spintech true duals, Kenne Bell s/c, Aquamist water injection.
|
deerridge
GenIII
3/02/2004
16:32:35
| RE: Fuel Mixture Changes?
IP: Logged
Message:
The guy that changed mine is at the Jonesborough Phillips 66, Tennessee. He changed the air fuel mix and the timing advance etc. I don't really know to what, but it worked good. I'll fine out the name of the equipment involved. I assume its' harder than it sounds.
On the hot gas issue, look up Intense Performances web site. He shows horsepower output at various temperatures. Cold air more power, hot air less power. THe whole point of cold air induction systems.
Real Horsepower
|
Sephiroth
Dodge Dakota
JOIN HERE
3/02/2004
19:08:15
| RE: Fuel Mixture Changes?
IP: Logged
Message:
Damn, so the 'Charles Pogue' carb I am builindg based on his designs will get the recorded 205mpg, but it'd take me two years to get up to speed? I know that when Pogue produced his carb in 1933, the oil-companies paid millions to get the patent, and then gave him a cushy job designing oil-filters, so I was thinking there's something to vaporized fuel. Is there any way to counter the power-loss due to running pure vapors? My friends and I were looking forward to this project. Now it looks like we'll be testing it on a riding mower...
|
WipLash
R/T
3/02/2004
20:47:49
| RE: Fuel Mixture Changes?
IP: Logged
Message:
The real trick would be to reformulate the fuel so that it requires more air to burn and still give off the same thermal energy. If you could formulate a new fuel that could be produced in mass quanities and operate at 20:1 air:fuel ratio, you would become the richest man in the world.
The problem with all our "alternative" fuels like alcohol, ethanol, and methonal is that they
require less air to burn. They also have a lower thermal energy. Therefore, they reduce the gasmileage when they are mixed with gasoline. All of the tree-huggers instist on them being used in order to cut down on pollution.
Their definition of pollution must be different than mine. I had an alcohol engine in my Late-Model. That thing would literaly choke you to death with the exhaust fuems. Your eyes would burn so bad you couldn't see. That's what they want us to mix in our gasoline to cut down on pollution. They are CLUELESS!
|
deerridge
GenIII
3/03/2004
10:51:27
| RE: Fuel Mixture Changes?
IP: Logged
Message:
The Determinator Pro-Scanner was used to change my air/fuel mixture from 14.7 to 16 and advanced the ignition a couple of degrees. He can change almost anything in the PCM. Experience and knowledge. He told me it was available all over and required to work on anything after 1995.
Real Horsepower
|
TexasTodd
Dodge Dakota
JOIN HERE
3/03/2004
13:30:09
| RE: Fuel Mixture Changes?
IP: Logged
Message:
Then is this waht they use at Kenne Bell, to flash a 2001, 4.7 PCM?
It seens that after 2000, it was near impossible to flash, or so they say.
|
WipLash
R/T
3/03/2004
13:40:37
| RE: Fuel Mixture Changes?
IP: Logged
Message:
That makes sense. I never understood why I couldn't get anyone to flash my 2002 4.7L. I'm going to confirm my air/fuel ratio to make sure my trcuk is actually running the way it's supposed to. It hasn't thrown a code yet. The 5.9L will easily run on 16:1. I don't plan to advance the timing. I may go 16.5:1. I'm going to modify the mount for the sensor so that it is adjustable. That way I can dial it in at the track.
Hughes sells a knock sensor kit for the Dodge. It's expensive. It is adjustable. It will automatically retard the timing when it detects detonation. It was originally designed to work with S/C systems, but it works on any engine. If I do the 16.5:1 and the Det-sensor never detects any pinging I may try advancing the timing then.
|
| | P 1 Next Page>> |
