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I have tried to locate a BSFC graph for my engine:

Dodge Dakota 4x4 V6 3.9L 275HP (1997)

but as of yet I have been unable to find one. I have reviewed the one that has been floating around on the forums here but that is for a small higher reving engine. I have been doing my best to pulse with about 63% LOD and keeping it under 2000 revs but it don't seem to be giving the results that I am expecting.

Can any one help me???? Please:confused:

BSFC charts hard very hard to come by, you may not be able to find one at all. I am still working on my P&G, but most here agree that a LOD of 75-85 seems to be the ideal range for most engines. You just have to find that sweet spot.

I have tried to locate a BSFC graph for my engine:

Dodge Dakota 4x4 V6 3.9L 275HP (1997)

but as of yet I have been unable to find one. I have reviewed the one that has been floating around on the forums here but that is for a small higher reving engine. I have been doing my best to pulse with about 63% LOD and keeping it under 2000 revs but it don't seem to be giving the results that I am expecting.

Can any one help me???? Please:confused:

Your tps should be increased as your speed increases. Do that while staying in the highest gear possible.

If that doesn't work, I'd try to find a clinic. P & g shouldn't be too difficult.

Thanks guys

I have usually been decreasing the TPS as speed increases as tourqe and HP increase. I will try and start at 30-35 and increase 1-2 TPS with increaseing speed. i will try and remember to come back and post any updates.;)

bringit, are you offering a clinic?? I would love if there were a clinica around the 4 states area as I have noticed there about a dozen or more poeple around the area here on the map.:D

Thanks guys

I have usually been decreasing the TPS as speed increases as tourqe and HP increase. I will try and start at 30-35 and increase 1-2 TPS with increaseing speed. i will try and remember to come back and post any updates.;)

bringit, are you offering a clinic?? I would love if there were a clinica around the 4 states area as I have noticed there about a dozen or more poeple around the area here on the map.:D

If you decrease tps as speed increases you are having a lot of losses due to slipping, which I'm sure is what the issue is if you are using P & G.

As for clinics, I'm up for giving them, however I'm in the Capital region area on the east coast which is quite a ways away from where you are ;).

Jason has a MT truck so there is no slipping to worry about. On the other hand, easing up on the pedal is taking the vehicle out of the ideal load range -- that's why the P&G isn't working.

Jason, swap around your method and start out with a lighter pedal (lower TPS) and increase it as you accelerate (higher TPS). Watch your LOD value and try to keep that about the same as you accelerate.

Jason has a MT truck so there is no slipping to worry about. On the other hand, easing up on the pedal is taking the vehicle out of the ideal load range -- that's why the P&G isn't working.



oh heheh...I didn't see where that was posted...oops:p.

Jason, swap around your method and start out with a lighter pedal (lower TPS) and increase it as you accelerate (higher TPS). Watch your LOD value and try to keep that about the same as you accelerate.
I agree. Lower tps at low rpm, higher tps at higher rpm. Aim for equal LOD the whole time.

Ok, thanks for the info, I tried it on the way home, but it didn't feel much different (21.0 over 13.1). I will keep trying it for next week and see if I can narrow in on the LOD and increasing the trottle.

I went from TPS 35-44 (which is getting to 100% TSP45), I guess it just seems odd to me to speed up the faster I go :o but so be it, I will keep the post going with information.

Thanks again guys. ;)

MT in the sigs ;)

what V6 do you have in your avenger bringit? Is it basically the same one as mine or something totally only for the car side of dodge?

what V6 do you have in your avenger bringit? Is it basically the same one as mine or something totally only for the car side of dodge?

I'm going to reply for him only because I looked up his car a while ago.:p It has a P.O.S. Mitsubishi 6G73 2.5 L V-6 mill, mated with a pretty decent Chrysler 41TE 4 Speed tranny.

I was hoping that the engine might be similar to see if we could compair numbers but since it is not, I guess it is back to my cold dark cave for me :0b

On the commute this morning I tried to keep the LOD at around 30 to 35, which is about 75% of the LOD, but I noticed that when I tried to keep a steady foot on the accelerator, the LOD values would go up as the speed increased. Is this normal? I don't know if this technique will transfer from a car engine to a truck engine that was built for torque. I will keep an eye on it and contiue with the trials

On the commute this morning I tried to keep the LOD at around 30 to 35, which is about 75% of the LOD, but I noticed that when I tried to keep a steady foot on the accelerator, the LOD values would go up as the speed increased...

Are a couple of those "LOD" supposed to be TPS or something else?

The specific x-mission in my car is tha A-604 (just one of the 41te). The transmission could have been a bit better though. I would have preferred to go into OD at 25mph, but it's set to 37-38mph :(. That means I rev EXTREMELY high (2400rpm) to get it to upshift.

The engine is too heavy for the power that it produces, coupled with poor mileage ratings. Chrysler's 2.0l was better.

Are a couple of those "LOD" supposed to be TPS or something else?

No they were LOD values. I am still trying to keep the TPS around 30-35 and that is right about 28-30 for LOD on Level ground. When LOD gets to about 33-36 TPS is up around 40TSP.

My TSP seems very short were 12 is idle and 48 is WOT. Is any one elses that narrow?

I tried to keep the LOD at around 30 to 35, which is about 75% of the LOD

I think he was talking about this

The engine is too heavy for the power that it produces, coupled with poor mileage ratings.
I hear that Ricardo, the 3.9L would seem to be under producting power from the size that it has. It always seems to be out of breath. That is why I got an Airaid intake for it, which does help out with low end power and torque which is where i want it now :D

I likes to cruise between 45-55 with out much effort, but getting it up to that is just a big hit on the tank. That is why I like to keep it on the highway more than in town.

I think he was talking about this

That was meaning that LOD at 33 is 75% of the max 44-45 for WOT or 100%. Does that help

LOD Value Percentage
4 0
33 75
44 100

It just seems odd that the LOD and TSP are so narrow on my truck.

LOD is (or should be) a percentage value that varies from X (a variable depending on the vehicle) at idle to 100 at WOT.

If your LOD never goes above 44-45, something is wrong.

LOD is (or should be) a percentage value that varies from X (a variable depending on the vehicle) at idle to 100 at WOT.

If your LOD never goes above 44-45, something is wrong.

Depends on how the manufacturer chose to interpret the definition of load. OBD-II defines it as airflow relative to maximum. But that could mean relative to the maximum possible at that RPM, or relative to the maximum the engine is capable of at that RPM (volumetric efficiency.) Or, it could mean airflow relative to the absolute maximum the engine is capable of at some high RPM. It is obvious from the readings I see on my Ford, GMs, and Toyota that they have all interpreted it differently.

Depends on how the manufacturer chose to interpret the definition of load. OBD-II defines it as airflow relative to maximum. But that could mean relative to the maximum possible at that RPM, or relative to the maximum the engine is capable of at that RPM (volumetric efficiency.) Or, it could mean airflow relative to the absolute maximum the engine is capable of at some high RPM. It is obvious from the readings I see on my Ford, GMs, and Toyota that they have all interpreted it differently.

I think you are right on this CarlD. I tried a little something different on the way home as I had 20 MPH wind with me (tailwind). :) To get on highway 249 (PSL 70) there is an elevated ram on to the highway, so I would also get a little help from gravity, I punched the gas in 4th and just let it go with WOT (the peddle to the metal as it were). by the time it was at 3350 RPM I had hit 73 MPH and cresting the hill to go to the valley floor, the TSP was at 75 and the LOD value was around 63. I guess at the lower RPMs the LOD is a function of how much air is being moved in to the engine because I can have the peddal down at low RPM's but the LOD will NEVER go over 30 until the RPM's build up over 2000.

However with WOT for that time didn't hurt the MPG to much as I ended at home with 21.7. :eek: I was put a little more gas in it than I normally do and it got back up to speed faster for the pulse. I am thinking I have not been giving it enough gas in the pulses. I will now try and keep the TPS value at 40-45(which is not the max that I thought it was.) I would also guess that the max LOD value is above 63 as well but I just didn't want to take the RPM's up to the max of 4275 to find out, I may have to do that another time.;) There seemed to little difference in the gas comsumption from the TSP of 35 and 40. I will keep you updated on the ongoing experiment. Thanks for the comments and the advise so far.

Some interesting info about LOD there. Mine (and most everyone's by the way they write here) reports it as a percentage at current RPM. My pulses are normally at about 75-80 LOD (sometimes a little higher. It goes Closed loop at 95%).

You might need to do some checking to see when it goes closed loop compared to TPS and go for a target TPS?

Some interesting info about LOD there. Mine (and most everyone's by the way they write here) reports it as a percentage at current RPM. My pulses are normally at about 75-80 LOD (sometimes a little higher. It goes Closed loop at 95%).

You might need to do some checking to see when it goes closed loop compared to TPS and go for a target TPS?

So, does this mean you can get LOD values of 75-80 at around 2000 RPM? I can't seem to get mine above 30 until I break 2000 and that is with the pedal on the floor.

I can get 100 lod at any rpm, by flooring the pedal.

I can get 100 lod at any rpm, by flooring the pedal.

Same here.

So, does this mean you can get LOD values of 75-80 at around 2000 RPM? I can't seem to get mine above 30 until I break 2000 and that is with the pedal on the floor.

SEems like you may have some Ecu issues, that or something else. Either ways, it may be hampering your fuel economy.

Could these odd values for LOD be because of incorrect settings on the SG? I don't know but That would be the first thing I would check.

I just had an idea. Watch your MAP gauge. It should read something low at idle, maybe 4 or 5 psi. That's a vacuum compared to 14 psi atmosphere. At full throttle it should read at or very close to 14 psi - no vacuum because of no throttle restriction.

75-80 lod pulses on mine are about 12 psi MAP.

pale, I will see what it says on the way home tonight and let you know.

The SG setup is pretty standard, with the fuel setup as hybrid so that it will not keep going off every time I turn the vehile off at the stop lights.

I can go through the setup if you all want to wade through it here.:)

Funny you should mention a vacuum issue. there has always been and issue with the HVAC system when under heavy load from the engine (going up Mountians and steep slopes for extented times) the HVAC changes from the position is on (Air with main vents and lower vents on) and then just cycles through the different positions (main vents/defrost/nothing) until it just shuts off completely, but the dealers that I have had look at it say that is normal. NORMAL, this is the only vechile if have owned that doesn't stay where I put the HVAC knob. I wonder if there is design flaw in this system with the vacuum lines.

Any way I will look at the MAP on the way home under WOT (you know if i didn't know better I would think you trying to reduce my over all MPG for the spring challange, has someone paid you off;))

As far as the settings on the SG, I believe all you would need to check is the engine size and cutoff setting. I have only had mine for a few months so I am still learning. I am sure others here would be able to give you much better advice in that regard.

Funny you should mention a vacuum issue. there has always been and issue with the HVAC system when under heavy load from the engine (going up Mountians and steep slopes for extented times) the HVAC changes from the position is on (Air with main vents and lower vents on) and then just cycles through the different positions (main vents/defrost/nothing) until it just shuts off completely, but the dealers that I have had look at it say that is normal. NORMAL, this is the only vechile if have owned that doesn't stay where I put the HVAC knob. I wonder if there is design flaw in this system with the vacuum lines.

Any way I will look at the MAP on the way home under WOT (you know if i didn't know better I would think you trying to reduce my over all MPG for the spring challange, has someone paid you off;))

Funny. I've seen that same AC position shifting on a ~1990 Dodge Dynasty and a similar year Dodge Caravan. They must be cousins.

Who do you think paid me? ;) Bwa-hahaha! :D

I used to get the same thing in the Ranger (back when WOT wasn't avoided like the plague).

As far as the settings on the SG, I believe all you would need to check is the engine size and cutoff setting. I have only had mine for a few months so I am still learning. I am sure others here would be able to give you much better advice in that regard.

Then I can tell you now,
3.9 L for the engine size as that is what I have.
Cut off setting is 16 because idle TPS is 12 (12+4=16)

Who do you think paid me? ;) Bwa-hahaha! :D

MR PANCAKE??? (no he wouldn't, would he:confused:)

Ok here are the results from the ride home:

Turned on MAP, LOD and TPS wth MPG on the SG

MAP sits at 14.4 or 14.5 with engine off (no vacuum)

At idle:
MAP = 4.5
TPS = 12
LOD - 4

At WOT
MAP - 14.2-14.3
TPS = 75 (pedal on the floor)
LOD = 63 at 3K RPM at 72 MPH (4th gear)

Pulsing trials
MAP = 13.9
TPS = 40-48 (MAP stayed about the same throuhout that range in the pulse)
LOD = 30-34 (if RPM is over 2K in 5th gear)

It felt like a much quicker pulse and was up to 21.0 MPG at the end of the highway section:)

So what does this information tell you or would you like some more informaiton to work from??

I think I have been babing the Pulse to much, if I go off of MAP and TPS I should be able to get closer to the bulls eye for efficent fuel usage. I am thinking TPS at 40-48 and keep the MAP up neer 13.8 since LOD does not seem to be working out to well for my vechile.


I may try a 2nd gear WOT to see if I can get the LOD to the top.

Ok, this moring I almost forgot to add LOD back to the guage before I did the next WOT experiment in 3rd gear to see what I can get for LOD Value. Man is it hard to keep an eye on the tach, SG, MPH and traffic while merging from an on ramp (downramp):eyebrow:

So in thrid I was able to take the RPMs higher to about 4K while the LOD value steadly climbed to 73 at about 62MPH when I shut it down because there was a truck in the left lane and a car in front that I didn't want to plow into (I just know that I wouldn't like that done to me :)) The MAX HP from the facotry is said to be at 4275 so I think if LOD values are suppose to be related to that then I would think that I am getting closer to the top values of the LOD. However, these values don't seem to help to try and get to the 75% LOD value becuase it will not get there in 5th gear under pulse appliction.

Does anyone have any suggestions? Should I just keep MAP up in the 13.6-13.9 range and TPS 40-50? Just from the seat of the pants feel it seems to be better than before (TPS 30-36).

Any other data that you want me to get for you?

2nd gear WOT? :eek: :D

It looks like your LOD reading is off. I think your idea of using MAP instead is a good one. I think your target might be a little high. I'd aim for the low 13s or high 12s instead. Test it and see what gives you better results.

Just watch out for the LOOP gauge - if it goes to "open", your mileage goes to "crap". At WOT, the computer gives up trying to match the air/fuel ratio, and just dumps extra fuel in there to be sure things don't go boom. Find out where the cutoff is for that, and then don't go past that.

Another thought in all of this: Much of the magic of P&G is from the Glide part. Aim for the trip mpg at the end of each glide to be higher than the one before. Make whatever pulse you need to, but if it's a heavy one, then you need a longer glide to balance it out. Hold out the glide until you see that trip mpg tick up one more 0.1 than last time, and then pulse it.

The MAX HP from the facotry is said to be at 4275
say what??

say what??

Yup your right I just looked it up and Horsepower @RPM 175@4800 it is the torque that come on at 225 Ib-ft torque @ 3200. It must be the allergy meds. :p

2nd gear WOT? :eek: :D

It looks like your LOD reading is off. I think your idea of using MAP instead is a good one. I think your target might be a little high. I'd aim for the low 13s or high 12s instead. Test it and see what gives you better results.

Just watch out for the LOOP gauge - if it goes to "open", your mileage goes to "crap". At WOT, the computer gives up trying to match the air/fuel ratio, and just dumps extra fuel in there to be sure things don't go boom. Find out where the cutoff is for that, and then don't go past that.

Another thought in all of this: Much of the magic of P&G is from the Glide part. Aim for the trip mpg at the end of each glide to be higher than the one before. Make whatever pulse you need to, but if it's a heavy one, then you need a longer glide to balance it out. Hold out the glide until you see that trip mpg tick up one more 0.1 than last time, and then pulse it.

I will put that up on the SG screen and see what the LOOP is doing on the way home. And I have been trying to Glide longer (which is getting easier with the warmer temps):D. If there is no one coming up for a awhile and I am pulsing up to 60 I will let it glide (NICE-on) to 40 before I pick it back up. But there are a few spots on the highway interchange that I don't want to be caught doing 40 up hill. So, I try and keep it around 55 through the interchange as to not impead traffic in that area.

I found this:
http://www.cleanmpg.com/photos/data/522/power-39.jpg

Now if i can get the lower graph I would have the BSFC i was looking for. What is the lower graph line, gas consumption?

From that chart, peak torque is at 3200 rpm. You don't want to be going that high, though. The step at 2000 looks like a good spot to aim for. Mine is similar, with a lower peak around 2000 and another peak in the 3-4k range.

That is what have been shooting for in all my shifting points is 1800-2000. :0)

I guess if I wanted a Fuel consumtion graph I would have to do it with the SG to GPH (Gal/hour) and get a number for at least every 500 or 1000 RPM point. Is that what you would do? Or do you think it is not worth it and just stick with what we know now.

Shift at >2000K
Pulses
TPS = 35-42 (as you stated not to really go higher andrew)
MAP = 12.5-13.1 or so (depending on the data from tonight with LOOP readings.
Then glide as long as possible (45-40 depending on traffic);)

Sounds like a good starting point. You'll have to adjust it for hills and traffic, like you mentioned above.

I've considered mapping out my BSFC, but it'll take a lot of work. You really need to do multiple runs at varying tps points as well.

:eek: not sure I have that much time, atleast not right now.

Ok sorry for being late tonight, we just got home from services and put the kidos to bed.

Alright, it was a nice day to test as it was 84 and no wind.:D (I still got 22.4 (think that had mainly to do with the weather and no wind) pulling into the driveway, I had over 23 until I hit town.:eyebrow:)

After getting all the displays on the SG and getting on the highway and got to my first spot to P&G I started at 45 MPH in 5th and put the Trottle down:

TPS = 35 (normally what I was using)
MAP = 12.6
LOOP - Closed

started increasing the pulse until I got to 60 MPH
TSP = 40 (new possition)
MAP = 13.6
LOOP - closed

TSP = 45
MAP = 13.8
LOOP - closed

TSP = 50
MAP = 14.1
LOOP = closed

I noticed after a few pulses that the LOOP value would change when TSP was over about 55 to Open, but this was about the time I reached my 60 limit. I would not normally push the trottle from 35 up to 55 on a pulse. I usully use 35-45 or 48 max.

What do you think?

I think I will try to only do the new pulses and longer gluides tomorrow to see what happens, althought we are suppose to have strong winds from the South tomorrow (good for the trip to work, but head wind on the way home).

It looks like all of your pulses were just after a bump start?

It takes the engine a few seconds to go from closed loop to open loop operations after a restart.

That's what you were noticing the few times it did switch to open (the Ranger often switches to open right at the end of some of my pulses).

I am not typically using NICE-Off glides. I am only doing that at this time to coast to lights that have just turned red and they will be a few minutes. I got to engine braking until I am in open loop, and then turn the engine off as it will then read 9999 when it wakes back up instead of the milage that it was when I turned it off.

I mainly am still NICE-on gliding, because I have noticed after I bump start the ICE must think that it is cold again because the idle RPMs stay above 1100 instead of the 750 when warm. This is also why I try not to get caught at a light where I have to shut down because it does the same thing if I have to sit there very long, so it kills any glide after the initial start from the light once up to speed.

The only time I see it in open loop is in engine braking, just starting the cold engine, and when I go from some stead state driving to gliding, the loop will go open and I will get 9999 on the iMPG read out and then it catches back up.

I thought there were only 2 values in the SG for LOOP, Closed and Open.

Those are the only two. I edited my response aboe so it may be less confusing.

I can't be sure if my memory is backwards, or if your truck is reporting backwards.

Hmm... someone else will chime in on that, I am sure.

It looks like you don't really have to worry about hitting the fuel enrichment of WOT, then. As long as it's in Closed Loop, you still have the computer adjusting the fuel mix. Some vehicles are much more eager to go to Open Loop and enrich the mix, but yours is not. I gave you a nearly and practically false alarm.

It looks like you don't really have to worry about hitting the fuel enrichment of WOT, then. As long as it's in Closed Loop, you still have the computer adjusting the fuel mix. Some vehicles are much more eager to go to Open Loop and enrich the mix, but yours is not. I gave you a nearly and practically false alarm.

So my memory was backwards (or my truck is reporting backwards).

If mine isn't in open loop for some other reason (just started) it won't go open loop until 95% LOD.

Sounds like pulses with max TPS of 45 to 48 would be good (just don't let it hit that 55 or so when it goes open loop).

right o, I will give a shot at these numbers for a few days to see what we get

Thanks all for the help and sticking this out with me, especially Taleisin, Andrew, Ricardo

Here's to your continued MPG improvement!

even with the wind today 22.0 on the way home. I am still sure the warm weather is helping :D

23.6 with the S wind @20-25 this morning.

22.3 with a very stiff south wind at 25 Gusting to 35. I could feel that I made ground on the wind with more trottle (not going above 50) but since the wind was fighting me so much I was not able to gluide as long a normal.

I have a nice 1/2 mile gluide that is down hill so I crest the hill at 45-40 (where the PSL changes to 35) and just NICE-on glide the bottom which nets about 1.5 MPG raise. I have to add a little Load to guide it up a little hill to sustain 35 and then coast it down and then up again to a light which I can see for a ways away so I know if I will have engine break a little of coast with engin off. It is a much better route than a 55 PSL road that crests the hill and is all down hill to a light you can see until you are over the hill and by that time there is not much you can do.