Well gang... I've been playing with theories and ideas for long enough now its time to put them into a design and see if it actually works. We all know the 24V's seem to take a good tumble in MPG's as the winter sets in well ISX proved that with the 12V engines with static timing that MPG's don't change. Well if you look at it the only thing that could be tossing this out the window is the IAT sensor on the 24V is changing the VP44 performance. Most know that colder air produces better HP/TQ because colder air is denser and requires more fuel to keep balanced. Well if you reverse this and warm the air (in theory) the VP44 should retune and burn according to the manifold temp. So what I've done tonight is fished through my resistor pile and found 3 I'm going to use for test candidates. Orange - White - Red - Gold = 3.9K Ohm = 116*F IATRed - Violet - Red - Gold = 2.7K ohm = 132*F IATRed - Black - Red - Gold = 2.0K ohm = 148*F IAT So now tomorrow I'm going to pull 3 test runs on the same piece of highway... Seeing if the highier the IAT temp increases the MPG or not... I'll can give you something to think about... Grid heaters are NOT controlled directly by the IAT... With the 2.7K Ohm resistor in place before even starting the grid heater still where hitting as normal. So there is more to the grid heater that the IAT temps... ... On the cutting edge again...

As Stodg said, there are differences between the HO and the SO, etc. I'll try to get the gritty dirt on the differences in them, as I spent a little time with my buddy, who builds big-power Cummins engines from street stock to unlimited truck-puller stuff.. He started spewing at the mouth, all of this verbal diarrhea at a rapid pace, and all I managed to gather from it all, was the little excerpt above. I'll try to nail him down for some more education.

I know the folks at MADS (they make and market the smarty) has but they don't respond to the emails I sent them in the past. (perhaps they only speeka da italian and I only typa da engliss) Jim

so just to help clarify a little (u know for us knuckleheads) this has been quite the thread to follow, but Mopar has found a resistor that tricks it into beliving its summer time correct??? and if this is correct then has the final edition been decided upon?

Well its a small step in the right direction the fact of fooling the IAT to believing its summer temps. It does bring up the MPG's a small amount. But what I'm after is to make the truck to believe its a 12V Ppump with fixed timing where I place it. (Fixed resistor).

ok i see and you got about a 5-6 mpg gain out of the resistor u've already tried??? does a p-pump 24v get the same kinda mileage that a 12v truck would?

ok i see and you got about a 5-6 mpg gain out of the resistor u've already tried??? does a p-pump 24v get the same kinda mileage that a 12v truck would?

Johnfak started this thread on the cummins forum to find that out.

http://www.cumminsforum.com/forum/98-5-02-24v-p-pump-conversion/352384-ppump-mpg-after-conversion.html

Jim

Johnfak started this thread on the cummins forum to find that out. http://www.cumminsforum.com/forum/98-5-02-24v-p-pump-conversion/352384-ppump-mpg-after-conversion.html Jim

Well after doing a long haul today to Boise, ID and back home in roughly 32-35*F weather slightly rainy but road condition was good but the fog was harsh at times... But my high mark for the trip is right at 20 MPG period... So now I need to change up the resistor and go down towards 100*F because I'm sure now that 132*F (2.7K ohm) is too high... It does yeild better MPG's over the IAT sensor but now I got to tune it in more...

What about using a potentiometer inside the cab and putting the scangauge on instant MPG and IAT temp and finding the flattest road, setting the cruise, and just turning the dial until you see the best number..

You could but I'm trying to find a solid form of the number... Being I've got buckets of resistors I can just swap them out... Since everything is under the hood any how...

How many months will it take you to find the resistor that works the best? We have a month worth of the 2.7K resistor.. I don't see why you couldn't figure out the best setting by taking ONE trip to boise with a POT.

Just for fun this morning I darted out to the shop and found a 50K Ohm pot and hooked it up...It ranges from 13*F to 292*F (0 Ohm also P0112 throw with CEL) Problem its not user friendly at all... Below 50*F the adjust is easy to hit. But not above 50*F the slighest movement jumps like 50*F... But it allowed me with some steady hands to adjust to 101*F for now. So the rheostat idea works but its not user friendly by no mean while driving.

Just for fun this morning I darted out to the shop and found a 50K Ohm pot and hooked it up...It ranges from 13*F to 292*F (0 Ohm also P0112 throw with CEL) Problem its not user friendly at all... Below 50*F the adjust is easy to hit. But not above 50*F the slighest movement jumps like 50*F... But it allowed me with some steady hands to adjust to 101*F for now. So the rheostat idea works but its not user friendly by no mean while driving.

Well yeah it helps to have a 5K pot.. Your trying to hit mars with a paper airplane with a 50K one. Even so, it may allow you to figure out the IAT relationship with the engine if you can vary it while driving and watch all the stuff on the scan gauge. It just drives me nuts that the stuff we really need to know (TIMING!) is not known.

It just drives me nuts that the stuff we really need to know (TIMING!) is not known.

Yeah don't we wish we could break out the old school timing light hook it up to #1 injector line and see timing... (Seriously) It would be nice to know exactly that information...

i think we need to figure out if the VP44 even reports the timing to the ECM. i have read that the FPCM (fuel pump control module, ie vp44's computer) has final say in fueling and timing. if it does report it to the ecm, then it would be possible to monitor it.if i am right, anything on the CCD bus has "access" to everything on the bus. each module only looks at a small spectrum of the bus. like a television. you may be able to pick up several station, but you can only watch one channel(the one you are TUNED into) i believe that all info could be accessed if you have a device that can "tune" in to the proper frequency. i have had limited success using the ELM327 as it gets its info from the ECM/obd.

Yeah don't we wish we could break out the old school timing light hook it up to #1 injector line and see timing... (Seriously) It would be nice to know exactly that information...

I have seen a timing device for diesels using a piezoelectric pickup clamped to No 1 cylinder injection line and set to trigger a strobe light to light up a chalk mark for TDC on the damper. http://www.ferretinstruments.com/Ferret/765/765.html $259 is a little pricey since strobe is extra. Apparently a guitar pickup is piezo electric if one looks at the Wikipedia writeup. Failing that one, could use an oscilloscope with delayed sweep. Channel 1 probe on the vibration damper pickup for tach and sweep trigger on piezo pickup on no 1 inj line. One would have to measure exact number of degrees that tach pickup is off TDC and do some arithmetic. I am not talking first hand, as I have only been thinking of this when running into the problem myself on my 97. I bought the dial guage setup instead due to difficulty in finding suitable piezo device that would not be trial and error.

man that would help a ton! and help answer a bunch of questions!!! thank you.

i think we need to figure out if the VP44 even reports the timing to the ECM. i have read that the FPCM (fuel pump control module, ie vp44's computer) has final say in fueling and timing. if it does report it to the ecm, then it would be possible to monitor it. if i am right, anything on the CCD bus has "access" to everything on the bus. each module only looks at a small spectrum of the bus. like a television. you may be able to pick up several station, but you can only watch one channel(the one you are TUNED into) i believe that all info could be accessed if you have a device that can "tune" in to the proper frequency. i have had limited success using the ELM327 as it gets its info from the ECM/obd.

The infamous 216 VP44 death code only indicates "maximum timing can not be attained" which is just a TRUE or FALSE status rather than an error value (12 bit or whatever). I think that tells you it can not report timing via CAN-BUS although the VP44 itself measures it for internal use. I believe it has more to do with processing capability and CAN-BUS speed back in 1996 in such a hostile environment in a small space when this was designed.

ccd and can bus are similar but different. CAN bus is ISO15765-4, and CCD and SCI is J2534 passthru. both are multiplexed bus(meaning it has several signals or data running at the same time thru the same wire, possibly in different directions). my ELM 327 only connects to the dodge using ISO9141-2. the elm 327 does various versions of CAN bus, but i receive a lot of bad data(the buad rate isn't matched, causing the bad data).

most OBD2 codes are a pass/fail or true/false. so i still think that the ecm MIGHT get info from the FPCM. i think the ecm would need that info to make the fueling pulse(which is both timing and duration) to make the most power/ meet emission standards. my elm 327 can read spark timing on gassers(obd2 certified ones, that is).

here is a link to a slideshow that explains car computers for dummies. pages 23-25 talk about CCD and CAN.

https://docs.google.com/present/edit?id=0ARHyLR2_DBOgZGZwOXA2Z3RfMzJjNzl0NWhmag&hl=en&authkey=CMbFopkK

i don't know about anyone's elses ecm, but mine is not fully OBD2 complaint.

--- Update to the previous post...

i found a pdf that was made by B&B Electronics Manufacturing for a device called Via LDV and says it supports SCI. i could not find the LDV on their site. when i clicked on a similar device it redirected me to www.autotap.com and to quote a page about PCM flashing:

Not Just Dealers Anymore

Until recently, car dealers were the only ones who had access to the tools and software needed to reflash PCMs. Thanks to the passing of Senate Bill 1146 in September 2000, vehicles manufacturers must now make this technology available to independent repair shops at reasonable cost.

Starting in 2004, flash reprogramming procedures must also conform to SAE J2534 standards which allow the use of aftermarket scan tools or similar pass-through devices that anyone can purchase and use.

Reflashing PCMs requires three things: a scan tool or pass-through reprogramming device that is J2534 compliant, a Windows 98 or higher PC with a modem and internet access for downloading the flash software from the vehicle manufacturer's website, and a subscription to the manufacturer's database so you can access the software. Other items that are needed include a cable to connect the PC to the scan tool or J2534 pass-through device, and a cable to connect the scan tool or J2534 pass-through device to the OBD II connector on the vehicle.

For GM applications, you need a Tech 2 scan tool or Vetronix Mastertech.

For Ford applications, you need a Ford New Generation Star (NGS) scan tool.

For Chrysler applications, you need a Diagnostic and Reprogramming Tool (DART). Chrysler dealers use the Mopar Diagnostic System (MDS2) and DRB III scan tool.

For import applications, you need whatever factory scan tool the dealer uses, an aftermarket scan tool with reflash capabilities for that vehicle, or a J2534 pass-through device that will work on the vehicle.

NOTE: AutoTap does NOT allow PCM reprogramming at this time. But you can use your AutoTap Scanner after a PCM has been reflashed to verify the system is functioning correctly (no codes or other problems).

has anyone used a CUMMINS INLINE?

I had someone build me an IAT fooler for my truck, because I don’t really know how to use a relay and soldering gun. I took a run to Denver and back last Friday and here are the results: going to Denver 18.841 MPG without fooler on, coming back from Denver 20.380 MPG. On this trip, I tried to keep my speed consistent, using the cruise control. Everything in my sig. is current. Yes, the propane was on for both runs, that way there was no difference other than the fooler being on. Out here the speed limit is 75 MPH on the highways, so the 1.5mpg difference should be more drastic as the speed limit is lowered.