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Timing a VP44 - Quest for MPGs..


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Some info I've saved over time from TDR

Timing the VP44 Fuel Injection Pump

The Cummins 24-valve engine was designed to meet

the tighter EPA federal emissions regulations of January

1998. An essential feature of this engine was the use of

electronically-controlled fueling events. The Bosch VP-

44 injection pump (see Figure 10) was already in use in

Europe for smaller engines, and was fully electronically

controlled with regard to injection timing and fuel quantity.

This pump delivers fuel at high pressure (1000 bar or

14,500 psi), almost as high as the P7100, to assist in

meeting emissions requirements. The size, weight, and

cost of the pump are much lower than the P7100, more

like the VE pump. However, the new VP44 pump differs in

several important respects from the older pump. In order

to develop the higher pressure it produces, it uses three

radial pistons to pressurize fuel instead of one axial piston.

While the engine mechanically rotates the pump, as with a

VE pump, the fueling commands are all performed via onboard

computer (fuel pump control module). While there

are different Woodruff keys for the VP44 pump shaft, you

cannot advance the pump timing with them. The computer

will normalize the timing to specification.

As soon as the 24-valve Cummins engine appeared

with our Turbo Diesels, in January 1998, some owners

of the new version of the Cummins B series engine

began complaining that they wanted more power.

Several aftermarket companies addressed the problem

and found that electronic solutions were the most

straightforward to develop and install. Some of the

power-adding products also added timing advance. The

VP44 injection pump is mechanical but is surrounded

by three computers. First is the Dodge computer on the

firewall, second is the engine electronic control module

(ECM) on the driver’s side of the engine, and third is

a computer on the top of the VP44 pump itself. The

ECM has proprietary software controlling the fueling

parameters, and the fueling commands are sent to

the VP44 computer through CAN-BUS communication

protocols.

The electronic enhancements made by

aftermarket firms have used one or more of the four

techniques listed below:

1. Intercept the CAN-BUS communications to the VP44

computer at the multi-connector that plugs into the

pump. This process entails unplugging the connection,

and putting in a Y-connector that goes to the aftermarket

“black box” computer. This add-on computer then

replaces some commands from the ECM with new

ones. One brand (example) that uses this technology

is the BD Plug-n-Power.

2. Add new instructions along the CAN-BUS using the data

link/diagnostic connector at the engine wiring harness.

This connector is used by Dodge and Cummins

technicians to access the ECM for engine diagnosis,

and to reprogram the ECM. The Edge Products EZ

box uses this system, and their Competition Box uses

both this technique and Technique #3.

3. Intercept the fueling signal coming out of the VP44

computer that holds the fuel solenoid of the pump

closed. This signal determines the time duration that

high pressure fuel is available to the injection line

and injector. The insulation of this wire is pierced

by a Scotch-Lok or similar connector so the addon

aftermarket computer box can receive this signal

and add another immediately afterwards to hold

the solenoid closed longer. The percentage of the

original signal’s time duration that is added to it by the

aftermarket computer box will determine the power

increase. This technique was introduced by Blue Chip,

then followed by a similar approach from TST, and later

Edge Products.

4. Reprogramming the ECM fueling and/or timing advance

curves.

Techniques 1, 2 and 3 require an additional wiring harness

to the manifold absolute pressure (MAP) sensor on the

side of the cylinder head at the intake plenum, if they

are to provide large power (fueling) increases. The ECM

generates defueling commands when turbocharger boost

goes too high (reportedly, over 20.5 psi). The aftermarket

computer harness puts a Y-connection into this harness

at the MAP sensor. The box intercepts the boost signal

and replaces the signal going to the ECM with an adjusted

voltage that indicates to the ECM that boost is within the

acceptable range, even when higher boost is actually

present. In this way, sufficient boost becomes available to

burn the additional fuel efficiently.

Add-on “boxes” that use Technique 3 take the engine rpm

and ECM-generated fueling level signals from the pump

wire. Boxes that receive CAN-BUS signals, including the

Edge Comp box that uses both Techniques 2 and 3, take

rpm and fueling commands from signals along the CANBUS.

Electronic power enhancement “boxes” that also add timing

include, among others, the Edge Mileage Max and the Juice

module with Attitude gauge and control readout box.

The Smarty programmer gives the option of adding timing

in its re-program of the ECM (Technique 4).

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Good info. I think the VP will be a pretty hot pump here in the near future when UDC is released for it. UDC for the CR is 1st on the list, but it will hit the VP community. Think about the timing/duration possibilities!

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Good info. I think the VP will be a pretty hot pump here in the near future when UDC is released for it. UDC for the CR is 1st on the list, but it will hit the VP community. Think about the timing/duration possibilities!

please explain :) english version too :):tongue:
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The software I have been using to write my own timing/duration tune for my truck is going to be made available for the VP crowd as well. You can fine tune for mods and power goals.

*shrug* - seems like QUAD tuning to me - just ability to custom tune. It really didnt do much for me when I had it - by that I mean it gets old very quick fiddling with stretch/ timing/duration/tps/fuel rate .... maybe Im missing the point ..:shrug:
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Its a lot more than any other "custom" tune out there. Say at mild acceleration your getting too much smoke and slow spool from 1200-1800 rpms. You can adjust the parameters for that area to help you spool quicker. You can then adjust 1700-2400 rpms and light load for better empty mileage, but get back into a good parameter for towing and hill climbing. Or if your getting a hair too much fuel WOT from 2800-3000 you can dial that back, etc. Take a look at the UDC software demo on the MADS website.A juice just manipulates the stock signal, this creates an all new stock signal. No tricking the VP44, or anything else. If you want 22° of timing at 2400 rpms from 80%-100% throttle you can have it.

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The Smarty UDC would be a awesome tool in the right hands for tuning... But the problem I see coming is the puppies (teenagers) out there will turn up the fuel to max for smoke value.Beyond that it will take some sit down study time to do a good tune for your conditions. :think:

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The Smarty UDC would be a awesome tool in the right hands for tuning... But the problem I see coming is the puppies (teenagers) out there will turn up the fuel to max for smoke value. Beyond that it will take some sit down study time to do a good tune for your conditions. :think:

It is a slow process. I had a great tune on my 7th try, and then wanted to see some effects of a few tweaks, now I am on my 13th tune. All it great, just minor stuff at this point. There will always be idiots!
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The last few tunes have been tweaking the low rpm and cruise rpm/load settings. I think I like where it is. I got just over 17 on the last tank and there was plenty of WOT runs, something that should have gotten me in the 15-16 range previously. Time will tell, but it also seems to be doing a bit better towing.

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Like yesterday I set out for a trip down to Boise, ID to hit Harbor Freight picking up heavy duty garden hose and such. Left home drove down US95 picked up fuel at Maverik in Payette, ID for 3.889 a gallon. Then proceed on the US 52 over to Emmett, ID and came in the back way of Garden City. By the time I hit Garden City I was just tipping 25 MPG on the ScanGauge II. The whole time of driving around Boise I was holding 24.5 MPG and not changing even with all the stop and go traffic for a Sunday. Finished up and we went up US55. Here is where I lost some of my nice high number by the time I reached Cascade, ID I was down to 23.0 MPG. But then I had a nice downhill run from McCall, ID to home so when I pulled in the yard I was right at 24.5 MPG... Not bad for doing the loop... http://goo.gl/maps/UzG9

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Like yesterday I set out for a trip down to Boise, ID to hit Harbor Freight picking up heavy duty garden hose and such. Left home drove down US95 picked up fuel at Maverik in Payette, ID for 3.889 a gallon. Then proceed on the US 52 over to Emmett, ID and came in the back way of Garden City. By the time I hit Garden City I was just tipping 25 MPG on the ScanGauge II. The whole time of driving around Boise I was holding 24.5 MPG and not changing even with all the stop and go traffic for a Sunday. Finished up and we went up US55. Here is where I lost some of my nice high number by the time I reached Cascade, ID I was down to 23.0 MPG. But then I had a nice downhill run from McCall, ID to home so when I pulled in the yard I was right at 24.5 MPG... Not bad for doing the loop... http://goo.gl/maps/UzG9

Mike, I know injectors can help with MPG (which is a good reason why I want some), but do you think that camper shell helps you some?
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Yes the topper helps a bunch. My topper is nothing more than a beer can. I weighs less than 100 pounds and I can lift it off by myself. This so sweet because it keeps aerodynamics and the topper weight is near nothing. Everything I've done for my truck is in regards to MPG efficiency. I can careless if my tires look too small or my truck isn't tall enough or am I making enough HP/TQ to compete with CF, DTR, etc... As long as my truck hauls the load from point A to Point B and returns back to Point A with good MPG's I'm happy. Then If I can continue to do it every day without failures thats even better! :wink:

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The Comp on 5x5 and 275's..........I'm sure you have zero trouble with any loads. Anyone need more towing power than that and they're hooked up to something far to heavy. :)Along with my mild EZ, I'd have either 275's or 75 hp sticks by now if it wasn't for having to replace the clutch with that additional power.

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The Comp on 5x5 and 275's..........I'm sure you have zero trouble with any loads. Anyone need more towing power than that and they're hooked up to something far to heavy. :) Along with my mild EZ, I'd have either 275's or 75 hp sticks by now if it wasn't for having to replace the clutch with that additional power.

Been there, done that... :duh:post-2-138698189468_thumb.jpg post-2-138698189473_thumb.jpg
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I used an Open Source tuning software application when I built my Subaru WRX beast. It was a steep learning curve, but once you got the hang of it, and what to look for, it was quite easy to make corrections and/or tweaks.John, I know there was some controversy in the Subaru world with the number of flashes of the ECU before you'd brick it. Granted, that number was quite high (1000s), is there any (same) concern with the Cummins ECM? I probably flashed my ECU hundreds of times by 3rd gear WOT pull logs, tweaking the maps, re-flashing, repeat, but I went from 265awhp/239tq on first flash, to over 500awhp/518tq when I was finished, with no other mechanical mods, only map table tweaks. Granted, this was a fully built stroker motor (2.5L block, knife-edged crank, Cosworth oil pump, chromoly h-beam rods,, Arias 9.6:1 coated pistons, 980cc injectors, 5-angle valve-job, undercut stems, flowed 2.0L heads, Garrett GT35R, 50mm EWG, 50mm BOV, etc., that I built to produce those kinds of numbers.Oh, and I DD'd this WRX 135mi/day, and still got 28mpg avg.

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