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McyMike
Dodge Dakota
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3/15/2004
15:55:16
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 Subject: Tail Pipe Soot - Rich Mixture?
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My 03 4.7 QC 4X4 tailpipe is always covered in black soot (rich condition). To me that means too much unburned fuel and could contribute to the poor MPG most of get with this little truck. Dodge says "all is fine". Do the rest of you with 4.7s run rich?
Mike
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WipLash
R/T
3/15/2004
20:34:29
| RE: Tail Pipe Soot - Rich Mixture?
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It's hard to get white exhaust tips running 14.7:1. The cats also make it hard to have white tips.
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Kowalski
Dodge Dakota
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3/16/2004
16:54:54
| RE: Tail Pipe Soot - Rich Mixture?
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A better way to tell if you are really running rich would be to read your spark plugs. I consider the 15 mpg I get without any effort at fuel conservation to be good milage for a tough 4WD truck that weighs over 2 tons - can't agree with your poor MPG comment. I've had lighter cars with bigger motors that made less power and got worse milage - bottom line is you just can't expect econobox milage from a truck.
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WipLash
R/T
3/16/2004
18:38:07
| RE: Tail Pipe Soot - Rich Mixture?
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Actually, the best way to tell if your running rich is to take a voltage reading from the O2 sensor. It should read around 480mv. That's 14.7:1. The higher the voltage reading the richer the fuel mixture.
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Dummy
Dodge Dakota
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3/16/2004
19:57:21
| RE: Tail Pipe Soot - Rich Mixture?
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WhipLash,how exactly would one go about taking a voltage reading from the 02 sensor? If you could explain it I would like to check mine occasionally.(4.7) Thanks.
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Rob C
Dodge Dakota
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3/16/2004
20:36:04
|  RE: Tail Pipe Soot - Rich Mixture?
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So, the answer is 'Yes' we do have black, sooty tailpipes also. I've been a little concerned about that also but, I'm not losing a sleep over it because the engine runs too well to have a serious problem.
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WipLash
R/T
3/16/2004
20:45:54
| RE: Tail Pipe Soot - Rich Mixture?
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You need a meter, preferably a gauge specifically designed to read milli-volts (mv). When the O2 sensor is heated it generates a voltage signal that is proportional to the the air/fuel ratio. Some have their own heat source and they are usually more acurate, especially when your running headers. Headers dissapate too much heat and cuts down on the efficiency of the O2 sensor.
The gauge/meter will simply hook to the wires on the O2 sensor and read the voltage output. If the sensor is the heated type, don't hook up your meter to the hot wire or you will get a 12V reading.
Dakota Digital makes a nice air/fuel meter that gives you an exact digital/numerical reading instead of a green or red light like most. It cost $110.00. You can do the same thing with a $20.00 multi meter from Wal-Mart.
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McyMike
Dodge Dakota
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3/17/2004
09:43:35
| RE: Tail Pipe Soot - Rich Mixture?
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I'll take the reading - there must be a way to lean this out electronically (hypertech or Dodge). I just drive the truck to work so squeezing max performance isn't an issue for me - a mileage increase would make my day.
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WipLash
R/T
3/17/2004
22:42:15
| RE: Tail Pipe Soot - Rich Mixture?
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I've started to do a research project on this several times, but always fell short of finishing what I started. I do know what must happen. Maybe some one else can take what I know and go one step further.....
The 14.7:1 ratio is 480mv (1mv= 1 milli volt = 0.001 volts)
The higher the voltage the richer the fuel mixture....
Now, you want to trick the computer into thinking it is running rich. Therefore, you need to increase the voltage signal coming from the O2 sensor slightly (100mv or 0.1volts). You would have to make a solid state circuit that would step up the voltage by 0.1volts. The PCM would then lean the air/fuel out until it got the 480mv signal from the O2 sensor. This would give you about 16:1 air-fuel. I'm sure someone has already done this. I could do it, but It would take me more time than I'm willing or wanting to spend on it.
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jeremiah2360
Dodge Dakota
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3/17/2004
23:46:13
|  RE: Tail Pipe Soot - Rich Mixture?
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WipLash,GraphiteDak could do that in his sleep(if he sleeps). He might try it. He could probably tell someone how to if he doesn`t.
I`ll give him a holler on the general board,see what he thinks.
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vern
Dodge Dakota
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3/18/2004
07:17:51
| RE: Tail Pipe Soot - Rich Mixture?
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try eagle-research.com,its a EFIE device for the
O2
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deerridge
GenIII
3/18/2004
11:56:38
| RE: Tail Pipe Soot - Rich Mixture?
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Most of the PCM flashes change the air fuel mixture. Mine was changed to 16:1. The exhaust still looks about the same. Mpg did improve, but not all that much. Maybe 1 mpg on all around driving. Ratio wise that's about what you would expect.
Real Horsepower
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FLDak
Dodge Dakota
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3/18/2004
12:58:28
|  RE: Tail Pipe Soot - Rich Mixture?
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I have a ROE A/F Controller with a A/F meter on my truck, '02 Dak 4.7 auto. Split Second makes the samething ARM1 and ARC1. The controller allows you to adjust the Low and High A/F ratio; Idle or WOT.
However when cruising down the Interstate the computer controls the A/F ratio. The way to tell is the A/F meter will dether(sp) or go back and forth in the middle of the gauge. When going downhill it will go to the lean side and when going uphill it will go to the rich side.
On the dyno I was able to squeeze 2-3 more HP out of the engine by adjusting the controller to the sweet spot.
Once on a trip I tried leaning it out to much and it tripped the MIL.
With all that said I think you have to have your PCM flashed to really change the A/F ratio all the time. However you can still effect it with a A/F controller.
Hope this helps someone...
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WipLash
R/T
3/18/2004
13:29:30
| RE: Tail Pipe Soot - Rich Mixture?
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deerridge,
I know your guy can do it by reprogramming the PCM, but then your stuck with it. If you have a signal amplifier between the O2 sensor and the PCM you can adjust the output voltage coming from the sensor to suit your needs. If you are going on a long road trip you could set it for lean. If your going to the drag strip you could richen it out. The PCM flash leaves you with a permanent change that your stuck with.
All you need is a step-up transformer that will increase the voltage from the O2 sensor 10%. That should be real easy to make. You can make a transformer that has multiple taps along the windings so you can choose the amount mof voltage increase you want. Then you can get really fancy and install a mutli position switch inside the truck that will allow you to choose which tap on the transformer you want. It will take me some time, but I think I can make my own step-up transformer that will do the job I want for less than $20.00.
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McyMike
Dodge Dakota
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3/18/2004
13:38:03
| RE: Tail Pipe Soot - Rich Mixture?
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Good ideas. Sounds like the variable adjustment would be the way to go. A little leaner for highway driving may realistically net a one MPG increase which would amount to about 25 more miles to a tank or almost saving two gallons of gas! I would do it if someone could figure out the technical hows.
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deerridge
GenIII
3/18/2004
14:04:10
| RE: Tail Pipe Soot - Rich Mixture?
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Being able to control it would be an advantage like Whip suggests. Then you could fine tune as needed. Doesn't sound like it would cost much either. I'm having mine fine tuned again today to see if more whoopy factor is available.
Real Horsepower
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McyMike
Dodge Dakota
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3/19/2004
09:13:09
| RE: Tail Pipe Soot - Rich Mixture?
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Whiplash - If you come up with something (sounds like you understand electronics better than me) please post the how to's.
Mike
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GraphiteDak
GenIII
3/22/2004
00:41:13
| RE: Tail Pipe Soot - Rich Mixture?
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I haven't looked that closely at mine, but I know there's some carbon in the pipe. I notice it when I take it to the car wash. It's normal.
If you're that worried you can pull the plugs like allready suggested. i think they should be a light brown, reddish color if it's ok. I'm not really that sure on fuel injected motor. I haven't had a problem to pay much attention to the plugs.
I did pull a few on my work truck. A P.O.S. 2000 Chevy 1/2 ton with the 4.8
It's got 93K miles and missing on two cylinders! The plugs looked ok. I think two injectors failed on that pig. It's got nothing on the Dodge 4.7 I'll tell you that!
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Rob C
Dodge Dakota
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3/22/2004
03:00:24
|  RE: Tail Pipe Soot - Rich Mixture?
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You gotta realize that Chrysler doesn't use that precise of a fuel injection system in the first place and then under many conditions the system switches to open-loop mode where it becomes even more of a WAG for the system to meter the fuel. GM, Ford and many other companies use the more precise mass airflow sensor system to meter fuel. This determines how much air is entering the engine and calculates the amount of fuel to inject based on the ratio of oxygen in air then monitors the exhaust with O2 sensors. Our system monitors air pressure, temperature and engine coolant temperature then estimates how much air is entering the engine and injects fuel then,it monitors the exhaust with O2 sensors and adjusts accordingly. Unfortunately, if the engine is cold or if you floor it or if there's a sudden big change in throttle position, the system switches to open-loop mode where it's not really being that precise. The mixture has to really be way off before you'll notice that something is wrong. As an example, we use to have carburetors in most vehicles and for the most part they weren't very precise yet our cars & trucks ran pretty darn good. Heck, I was working on my motorcycle today and installed some new carbs on it. When I went to start it, the fuel bowls hadn't quite filled up yet so it wouldn't start. I squirted a shot of ether into each carb and it started up and ran pretty good for about 10 seconds then, the ether ran out and it died. For about 5 seconds I thought I had gas in the carbs but, realized the engine was running on the ether.
Anyway, is your truck stock? Have you done any mods to try and get better mileage before you try fooling the PCM?
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mcymike
Dodge Dakota
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3/22/2004
08:43:13
| RE: Tail Pipe Soot - Rich Mixture?
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Rob C
If you're asking me, mods are synthetic oil, cold air intake with K&N, Gibson exhaust, and a very light foot. I know on this forum that a lot of members are into performance (so mileage concerns don't seem to weigh in with them) and that's cool, but I just use my truck to drive to work and haul my dirt bikes. If there was a way to lean the mixture (better mileage) and still have the truck be driveable...that would be great for me. If my 0 to 60 suffers a little I wouldn't mind.
Mike
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Rob C
Dodge Dakota
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3/22/2004
19:42:37
| RE: Tail Pipe Soot - Rich Mixture?
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Well, I've been trying to get better gas mileage too. However, I do care if the performance suffers. So far, everything I've done has improved both power and fuel economy. Some mods have been only a slight improvement but, when I add it all up, my average fuel econmy is up by almost 4 mpg. When I first bought the vehicle it was averaging 13.2 mpg overall. Now I average between 16.7 and 17.1 mpg. Lately I've been having trouble getting decent mileage because I did some mods and have been getting into accelerator a lot to put the engine through it's paces. Acceleration is addictive! If I keep my foot out of it, I do pretty good though.
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