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The "restification" of a 98 6.5 TD...

Heated washer unit is in:

6b764c50.jpg


3b39e1a1.jpg


Running out of space for relays and solenoids:

4e813343.jpg


That's a couple of Cole Hersee 85 amp continuous duty solenoids. One runs all the power to the interior components (cb, etc) and the other controls power to the washer heater.

The OE installation of the heater is meant to be wired to 12v hot all times and it turns itself on and off as voltage rises and falls above 13.6v.

But, I didn't like the idea of it deciding when it was going to draw power so the solenoid only allows power when the truck is running (triggered of 12v ACC). The heater is a 60A draw when it starts (turns off when it reaches temp), so I chose an 85A solenoid to power it.
 
Starting to plan the intercooler install since I'll be staying with my GM8 for the near future (does everything I ask from it and it's still only about 2 years old from GM parts).

Several schemes were considered from a top mount with a hood scoop:

IntercoolerFan0.jpg


(Not a fan of hood scoops)

to the ubiquitous "hanging ATA":

attachment.jpg


(absolutely no way that will work with the plow sub frame)

Water to air :

DSC01763.jpg


Well, never was really a consideration, although I looked at it. To much complexity for the same results.

The final decision is to install it in the rad core in front of the radiator.

First iteration will be with the Dodge intercooler I have sitting in the garage.

DSC03891.jpg


It will have to be modified to fit in the core support with the 6.5 radiator. The inlet/outlet tubes are not as wide as the 6.5 radiator.

In all likely hood one will stay the way it is, the other will become a straight out.

Then, the rad support will have to be modified.

The trans and oil coolers are as far forward as they can go. The Evap core is pretty much as far forward as it will go also.

That leaves moving the rad back. Measurements will have to be taken to see if I can get the 1 3/4-2 inches I need.

Considerations will be (besides rad clearances) where the cooling fan will sit in the shroud. If it's too "deep" it won't move the same amount of air through the core. There may be some modifications required to the plastic shroud as well.

The intercooler will impart some heat to the rad, but it will also help by lowering EGT's. Hopefully, that comes out "neutral" in the ability of the rad to shed heat buy lowering EGT's and imparting less heat to the cooling system.

I have a high flow pump on there right now, but will probably upgrade to the spin on pump/clutch/fan. In all likely hood, I'll just drop Bill my visa number and order it all up at once when the time comes.

The turbo will get "clocked down" and aluminum ducting will make it's way to the intercooler.

More aluminum will make it's way back up to the intake.

The upper intake will be a "modified" stocker. It's probably easier to go with something from Penisular like the marine upper, but I'm going to fab something up. reasons why are my own.


Unfortunately, I'll have to farm out a lot of the aluminum work since I don't have a TIG or spool. I may be able to get the boys at work to tig it up for me after I do the cutting and shaping.

I will be able to fab the rad support, the Z28 fender ducts and the door handles myself though.

Long term project here gents. Don't expect fast progress unless i get a burr in my butt about it.

As always, cash is in short supply......
 
Is the Dodge IC of a 93? I have one that looks just like it. I concidered it, but for me a water to air is going to be the best.

Looking forward to you door handle mod.
 
Thought provoking:

Originally Posted by author at maxboost website
Normal compression is adiabatic, which to a first order means that as the gas is compressed, it gets hot. Now this heat is one of the biggest problems with forced induction, for 2 reasons. Firstly you have to get rid of the heat, and secondly you need to take power out the turbine shaft to perform the heating.( heat is work and work is heat).
With the right level of water injection, the heat is removed before it builds up, pushing the compression closer to isothermal (not all the way, but closer). In round terms this is about 30% more efficient (less exhaust gas required for the same boost, or more boost at the same exhaust flow).
Problem 1 is that water on its own, whilst having a very high latent heat of vapourisation, doesn't have that good a saturation partial pressure. You can only put so much in before the air is at 100%RH. Above this the water will not cool the air until you compress it in the engine. However, if you add a second fluid, say methanol, Dalton proved with his law of partial pressures that the methanol doesn't know that the air is saturated with water vapour and goes on to vapourise as well. Add a 3rd, such as acetone (all available chemicals) and you get a 3rd tranch of cooling.
The net result is that you may be able to cool the air to slightly below ambient with the right mix. So your compressor becomes more efficient, you can throw away the intercooler, increasing your flow, and in some cases significantly improve the flow from turbo to inlet.
If you leave the intercooler in, you are generally warming the air back up again, so you have to take the plunge and remove it to gain the best benefit.
------------------------
You are working with a complex system of mechanical devices that interact with each other in many ways. Even though on first blush injecting infront of the compressor or between the compressor and the intercooler might appear to be less effecient you need to account for ALL the interactions. In many cases we simply don't have enough information to predict the results so frequently experimentation will give you better data in a matter of minutes, than all the incomplete computer simulations you can afford.
Injection in front of the compressor accomplishes several things. A turbocharger is a constant pressure variable volume "DYNAMIC" compressor.
A turbocharger only knows 2 important properties of the gas it is compressing. The density of the gas at the compressor inlet and the pressure ratio it is operating at, which is determined by the rotor rpm and the gas density. If you increase the pressure or reduce the temperature at the inlet you will modify both of those parameters. In both cases (increased inlet pressure, or lower inlet temperature) you increase the apparent density of the gas passing through the compressor. At a given rotor rpm with a given gas density you will flow a very specific volume of gas and it will be compressed to a specific pressure ratio on exit. That is what the compressor map is based on. If you change the inlet conditions (gas density) you in effect slide the compressor map left and right. This is the "corrected flow" of the turbocharger.
By injecting water/alcohol ahead of the compressor two things happen. You cool the inlet air substantially, this in effect moves your true operating point to the left on the compressor map. (in most cases for max performance this is a good thing, although on some turbocharger conditions it can cause compressor surge.)
You also change the pressure temperature profile inside the compressor wheel itself. You probably actually change the shape of the compressor map. As the gas moves outward and is compressed, heat that would have gone into heat and increased pressure is absorbed by the WI mist and so the compressor has less work to do since it is no longer fighting this temperature driven pressure increase, it can achieve more mass flow at that pressure ratio. The cooling should also modify the speed of sound in the gas and the mach number of the compressor blade tips should also change. This should change the choke flow characteristics of the compressor but I don't have the information to comment in detail on that.
Net result is, you increase the mass flow through the compressor --- in effect you make it act like it is bigger than under normal conditions.
During WWII this was the way ADI (anti detonation injection --- the common term in the aircraft world for WI ) was set up on military aircraft in most cases. The water and the fuel was injected into the eye of the centrifugal supercharger.
Errosion of the compressor blades is not a problem if steps are taken to ensure the mist is very fine when it arrives at the compressor inlet so that it follows the airflow and does not imping on the blades with a high differential speed.
The ideal is to get drop size down as close to 10 microns as possible but due to the brief periods of use and intermittent nature of most WI systems, in reality you can live with larger drop sizes in real world systems.
If you have ever ridden a bicycle or motor cycle in a rain storm you know how sharp the impact of a large water dropplet can be, but a fog or drizzle will not cause the same painful experience because the droplets are small enough they are strongly influenced by the direction of flow of the air stream around you and impact with much less velocity and obviously also have lower momentum.
For people in hot dry climates that lose a lot of turbocharger performance in hot weather, pre-turbo injection should be looked at.
In regard to the effects on the compressor mass flow, maximum results appear to occur with mist flow of about 3% - 10% of the air mass, so you will likely need to inject additional WI near the throttle body to reach maximum detonation suppression and best power.
--------
If you mean that the ambient temp air flow is affected, I wouldn't expect that to be much. Say ambient is 20C, how much lower can it get by injecting mist of water that's 30C+ (the bottle is in the engine bay!). I suspect that after the pump the water is even warmer.
Actually it can be very substantial. The cooling is by evaporation, and typically will exceed 10 - 20 deg C . The initial temp of the water is of little consequence. The cooling due to evaporation (latent heat of evaporation) is very much larger than the latent heat of the liquid water.
As you can see below the evaporation of a gram of water will absorb 542 x the heat energy required to lower that same quantity of liquid water one degree in temperature. That means that even if the water were nearly at boiling temps when injected, evaporative cooling would reduce the air flow temp below ambient temperatures long before all the water changed to vapor.
Specific heat capacity of liquid water - 4.187 kJ/kgK
Latent heat of evaporation - 2,270 kJ/kg
Since the evaporation of the water and the alcohol will essentially stop when the air becomes saturated (ie. 100% humidity) there is a practical limit to the cooling or around 20-30 deg C for alcohol water mixes, and in real systems you seldom get much more than about 15-20 deg C.
For every 5 deg C you drop the inlet air temp you will increase mass flow by about 1% due to density increases.
I would have thought that this 'efficiency gain' is the effect of water droplets inside the compressor blades, as they try to squeeze the air.
Am I right?
Only in a very crude sense. Your thinking in a mechanical piston pushes on air sort of way, but what happens inside the compressor impeller occurs at a molecular level.
Think of it this way If you could freeze frame time, and stop what was happening inside the impeller while its spinning at 120,000 rpm. Each impeller passage between adjacent pairs of compressor blades contains a wedge shaped parcel of air. When spinning at 120,000 rpm the air is subject to huge centrifugal forces as it moves away from the hub of the impeller and toward the rim of the compressor. The trapped air would like very much to be slung out of the impeller but like a crowd at a stadium after a match it simply cannot all get out as fast as it would like. As a result it stacks up (compresses) as it gets near the exit. In this process a lot of internal friction occurs. The air near the tips of the compressor might be moveing near the speed of sound at maximum flow, this heating makes the air try to expand. This increases the pressure which fights the outward movement of the air. Eventually a balance is achieved between the centrifugal forces trying to throw the air out of the impeller and the pressure build up due to the compression and the pressure build up due to the heating. The addition of the water mist removes a very large fraction of the pressure gain due to heating. As a result more air can exit the impeller over a given period of time, and more of the pressure gain is real compression rather than waste heat. The net result is a more isothermic compression which is always more effecient than an adiabatic compression.
-----------------------------
Injecting methanol really complicates the tuning process. Complete combustion (stoich) for gas is about 14.7 A/F. For methanol it is about 6.3. Methanol has less fuel energy than gas, but adds considerable quantities of oxygen. Adding, 10% methanol, to gas creates a new unknown stoich value somewhere in between, maybe closer to about 13.8...who knows? The oxygen sensor is primarily measuring the very, very small amount of remaining oxygen from the combustion process. A sensor calibrated for gas will read leaner once significant alcohol is injected (more oxygen is available). The issue is calibration. "How do you know exactly what the A/F accuracy is with this new fuel mix?" Unfortunately, you don't.
It gets even more complex when using a rising rate of alcohol injection. My SMC hardware starts at about 6 psi boost with 70 psi injection line pressure, and ramps up to 100 psi by 16 psi boost. So, now you have not only a new fuel mix, it is also changing. Trying to tune using conventional wisdom with target A/F values is a bucket of worms that may have no practical solution. It's even tougher, when there is no access to an AWD dyno.
-------------------------------------------------
A compressor moves a certain VOLUME of air. Even though most compressor maps list airflow by mass (lbs/min), it's actually a matter of VOLUME (CFM), that has been translated to mass by assuming a certain temperature and pressure (~25C and 1 atmosphere).
So, what this means is that a compressor that maxes out at say 55lb/min airflow on it's compressor map, should be able to flow about 10% more (60 lb/min) if the inlet temperature was 0C (0C air is about 10% denser than 25C air).
I imagine another big part of the limitation of the compressor is the amount of force of stacking up the air and compressing it. Although the ENGINE benefits from a intercooler, the compressor really doesn't care. It's still working hard, and making hot temps. These hot temperatures which result naturally from compression, work to expand the air, while the compressor works to contract it.
So, what if you could "intercool" the compressor itself? Add a mist of methanol/water to the inlet, which would vaporize and cool the air as it passes through the compressor? I'm still unsure on this, but wouldn't that mean a even bigger jump in the efficiency and upper limit of a given compressor, seeing as how it has to work against the air far less?
My guess here is that a compressor works on relative volume in vs out. When you see a compressor map, and one section says say 75% efficient at 60lb/min and a 3 pressure ratio. What REALLY matters, is how much volume is going in, vs going out. You get a 3x reduction in volume through compression, and gain 30% volume through heat expansion (25C in, 150C out). That's a mass boost of 2.1:1.
Now, IF the out temp of the compression process was reduced to say 40C through methanol vaporization, look what happens:
Pressure ratio of 3:1 remains
Temperature gain now only expands the air by 5%.
3*.95=2.85
So, if I'm not missing anything, the same compressor, operating at the same 3:1 pressure ratio, will be able to flow 2.85/2.1=35% more air if the air only heats up to 40C during the process instead of 150C.
Combine the gains of pre-compressor cooling to freezing temps, and the integrated cooling (actually heat gain reduction) during compression, and a compressor rated to only flow 55lb/min could flow: 55*1.1*1.35=81.675lb/min.
Click to expand...

preturboWI_temp_chart.jpg

this thread makes my head hurt:

http://forums.tdiclub.com/showthread.php?t=202520&highlight=water+injection

But lots of good stuff to think about in it...
 
International 6.9L Engine - Diesel Tech
The IDI Father Of The Power Stroke
From the March, 2007 issue of Diesel Power
By Ray T. Bomacz
Photography by Ray T. Bomacz


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International 420Ci Diesel Engine Engine Block

In March of 1978, the International Harvester Corporation started development of an engine that would eventually change the way pickup trucks and light-duty vehicles would be powered. The 420ci (6.9L), naturally aspirated (non-turbo), indirect-injected (IDI), diesel V-8 would find a home under the hood of Ford pickup trucks, and the diesel power culture would be born.

The Ford/IHC 6.9L engine featured a bore of 4.00 inches, a stroke of 4.18 inches, produced 170 hp and 310 lb-ft of torque with a 20.7:1 compression ratio. It may not sound like much by today's diesel standards, but 24 years ago it started a diesel revolution!

Engine Block
Made from cast iron, the 6.9L featured 4-bolt, nodular iron main bearing caps. This was done for reliability and also to increase the stiffness of the lower end of the block. In addition, typical of light-duty engines, bulkhead window core support holes were eliminated. This further increased stiffness and eliminated a potential area of failure.

IHC engineers used the then-new finite element analysis procedure to optimize performance. This study indicated that a significant reduction in deflection could be realized by increasing the bulkhead thickness in the area around the cam bore from 0.62 inch to 1.12 inches. This change was incorporated into the production engine.

The cylinder bores were not siamesed and were 0.26-inch thick. The five head bolt bosses per cylinder were not joined to the cylinder walls, but tied directly to the main bearing bulkheads through the outer water jacket walls or free-standing interior bosses. The design was used to minimize cylinder bore distortion during machining, assembly, and in operation. The front end of the engine block was extended to form a cavity for the geartrain and provided an ideal location for the fuel lift pump, thermostat, thermostat bypass, and water cross-over between the cylinder heads.

The 6.9L block also included many advantages in terms of flexible packaging for use in varied vehicles and to improve in-field service. The pan rail had tapped holes for oil pan mounting and were arranged for a reversible oil pan along with either a front or rear dipstick. The water inlet cavity provided flexibility for both size and location. Light-duty truck mid-engine mounting bosses and heavy-duty truck front-mounting bosses were included in the design. The engine block valley was cast open, and the roller valve tappets were serviceable without removing the cylinder heads.

A positive-displacement geardriven oil pump was located at the front of the first bearing cap and driven by the crankshaft gear. The pump was mounted to, and located by, the same machined surfaces as the bearing caps; doweled location holes were not required. Oil was routed via drilled passages throughout the crankcase. No external lubrication plumbing was required.
International 420Ci Diesel Engine Injector
The injectors were placed...

read full caption

Rotating Assembly
The crankshaft was designed to the same criteria that IHC applied to its heavy-duty line of diesel engines. For reliability, a forged steel material was chosen, which could be sufficiently strengthened. Through extensive testing, the operating stress levels were measured in the critical areas. From those measurements, the manufacturing process and heat-treatment requirements were established.

The crankshaft was forged from 15B28H steel and quench-and-tempered to a minimum hardness of 217 Brinell hardness number (BHN). The five main and four pin journal surfaces were induction-hardened to Rockwell hardness (RC) 50-55 for wear resistance and to allow in-service re-grinding. The pin fillets were induction-hardened to Rockwell hardness 50-55, then ground flush with the pin surface for fatigue life. The combination of processes and design provided a very strong crankshaft and a long service life.

External balance weights in the flywheel and a vibration dampener were required to keep the overall engine size within that of a gasoline engine and to limit the scrap rate during manufacturing.

The front and rear crankshaft oil seals were a one-piece design that were springloaded and featured trimmed flouroelastomer material. Both oil seals rode directly on the ground sealing surfaces-the front seal on the vibration dampener and the rear on the crankshaft rear flange.

The connecting rod and cap were forged from alloy steel as one part and cut into two pieces early in the machining process. In order to achieve adequate fatigue strength, the forging was heat-treated to obtain a surface hardness of Rc 27-33. This also provided adequate core hardness for surface strength of the critical stress areas. After heat treatment, the rough forging was shot-peened to provide a margin against flaws as well as undesirable residual stresses from operations such as straightening.

The small end of the rod used a steel-backed bronze bushing, which was pressed in place and bored to the final dimension. As was traditional IHC protocol, the rod design was proved acceptable by both static strain and fatigue tests prior to running in an engine.
International 420Ci Diesel Engine Cylinder Head Cross Section
The cylinder head cross-section...

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Pistons and Rings
The piston design focused on the durability that was an IHC hallmark. Although analysis had shown the mechanical strength would be sufficient, the required three compact ring package and short top land could result in high ring groove temperatures and a potential for ring sticking, poor oil control, and scuffing. However, a longer piston would have required increasing the block deck height with the resulting increase in engine dimensions. Finite element analysis was employed to predict the mechanical/thermal stress conditions and ring groove distortion related to the thermal concerns. The intention was to depend on oil cooling of the piston for temperature control, and the compact design was determined to be adequate, as initially proposed. An Alfin-bonded nickel-plated insert was used to control top-ring groove wear.

The piston pin was an extruded design made of a medium carbon steel that was carburized to control strength and wear properties. Its 1.11-inch outside diameter and 0.58-inch inside diameter, resulting from the extrusion process, provided strength and deflection control.

In order to provide adequate piston lands, relatively narrow rings were used compared to previous IHC diesel engines. Both compression rings were 0.08-inch wide. The top ring was a ductile iron, chrome barrel-faced design, while the second ring was a gray iron, positive twist, taper-face style. The oil ring was 0.109-inch wide and was made of ductile iron and spring loaded.

Cylinder Heads and Combustion ChambersA Ricardo Comet V combustion system was selected during the early stages of development for the 6.9L engine. It was chosen because of its modern design that would meet the stringent emissions requirements expected in the 1980s. The design would also provide a high power output and good fuel consumption at a relatively low cost.

The cast-iron cylinder head was a two-valve design with the combustion chamber placed in the piston crown. To reduce the valve bridge operating temperature, a drilled cooling jet was utilized. The cooling passage provided more uniform temperatures in the valve seats and eliminated the potential for valve bridge cracking during high-load uses.
International 420Ci Diesel Engine Intake Valve
The intake valve used an induction-hardened...

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Originally, an exhaust seat insert was an anticipated requirement with the heat load of an IDI engine. The inserts provide superior wear resistance and improve serviceability over non-inserted, induction-hardened seats. Early testing by IHC had shown adequate wear resistance. However, as testing continued, a problem of head cracking was encountered. Several modifications proved fruitless, so the exhaust insert design was reincorporated. The cracking problem was not encountered on the intake seats, which employed only an induction-hardened seat.

The head gasket design featured a solid steel core carrier that was 50 percent of the total gasket thickness. The rest of the gasket consisted of a rubber-abestos material. Combustion sealing was done with a free-floating solid carbon steel wire wrapped with a stainless steel armor. The armor was shaped with a "bib" under the swirl chamber insert to protect the underlying facing material.
International 420Ci Diesel Engine Fuel System
The fuel system used a very...

read full caption

IDI Fuel System
IHC used a Stanadyne DB2 rotary distributor fuel injection pump that incorporated a hydraulic speed advance and a light load advance for optimum timing over the entire operating range.

Additional advance was achieved during cold starting and warm-up to reduce white smoke and hydrocarbon emissions. A solenoid controlled by a thermo-switch in the cooling system unseated the ball valve of the housing pressure regulator. This reduced housing pressure, which allowed a greater amount of injection advance for the given load and engine speed.

The governor was a minimum/maximum design, providing control action in the low idle speed range and above the rated speed. Between these ranges, the throttle lever controlled the metering valve position. A snubber orifice machined into the distributor rotor indexed with the ports in the head after the main injection took place. The damper orifice reduced aftershocks in the injection lines and eliminated unwanted secondary injections of fuel.

Outward opening poppet nozzles were tested first with a 30-degree angle toward the swirl chamber wall and a smaller hole spraying 10 percent of the fuel toward the glow plug. Performance with this design was satisfactory, but hydrocarbon emissions were high and coking of the small 0.009-inch orifice proved to be a problem. As a result, inward opening pintle nozzles were developed to fit in the space confines of the 0.67-inch orifice nozzles. Performance, emissions, and durability all proved to be excellent with the new design-and nozzle coking was kept at a minimum.

The fuel system was mounted on the engine and included a mechanical fuel lift pump, inline fuel heater, and a fuel filter prior to the injection pump. A constant bleed orifice was used on the outlet of the fuel filter to eliminate the need for hand priming or manually bleeding the air from the system when the filter was changed or the tank was allowed to run dry.

An electrically activated glow plug was used in each swirl chamber to improve starting below 70 degrees Fahrenheit. The glow plug temperature was controlled by an electromechanical bi-metallic switching device, which pulsed 12 volts to the 6-volt glow plugs. The initial energized period of up to 10 seconds pre-glow produced glow plug temperatures that provided acceptable engine starting to minus-10 degrees. The system incorporated an after-glow feature that continued to activate the glow plugs for a period of about 1 minute after the engine started. This feature reduced the amount of white smoke developed on cold start until the combustion chamber walls were sufficiently heated. For starting below minus-10 degrees, a 110-volt electrical block heater was provided.

A Successful Design
The 6.9L engine underwent extensive development and durability testing before the start of production. A total of 160 prototype and 10 pre-production engines were built for engineering tests. The test engines had accumulated a total of 52,000 laboratory durability test hours and 815,300 miles of field tests by the time Ford vehicle production began.

The laboratory tests included:* 21,000 hours at full load
* 16,500 hours at 72 percent load
* 4,500 hours of special durability tests
* 10,000 hours on pre-production engines

The 10 pre-production engines were built and tested on the dynamometer to verify the quality of the production process. Each engine was subjected to 1,000 hours (approximately 80,000 miles) at full load, with no problems occurring. In addition, pre-production engines were placed in customer fleet trucks and subjected to varied conditions, drivers, and use.

Read more: http://www.dieselpowermag.com/tech/...onal_diesel_engine/viewall.html#ixzz1imjKoMKR
Click to expand...

Posted for personal reference
 
great white said:
Sheesh, why am I messing with this electronic gm diesel again?
Click to expand...

For the same reason you didn't listen when we told you to buy an HP4 and a TM... you like to do things yourself, you believe you can do it better, and you are a control-freak. :hihi:

I can appreciate those things; it's how you get such neat stuff... but no way is it easier. :D
 
LOL ... no insult intended, amigo; you DO build great stuff, and you ARE a freak about having things customized to your desires. The rest of us lunkheads take the compromises inherent with buying mass-market stuff, probably because we're lazy.

But an old saying comes to mind...

Hard work pays off eventually ... lazy pays off right now
Click to expand...

:hihi:

I wish I had your skills, I might build more of my own stuff.

...
...
...
Nah.
 
JiFaire said:
LOL ... no insult intended, amigo; you DO build great stuff, and you ARE a freak about having things customized to your desires. The rest of us lunkheads take the compromises inherent with buying mass-market stuff, probably because we're lazy.

But an old saying comes to mind...



:hihi:

I wish I had your skills, I might build more of my own stuff.

...
...
...
Nah.
Click to expand...

Self awareness is often the key to happiness......


:rofl:
 
Just a rotten, sloppy Newfoundland day coming back from St John's after the wife's dental surgery:



Towards the end she catches some slop on the side and pulls right. It jerks the truck hard enough that she woke up, that's where you hear me say "it's sloppy".

Winter storm was trying to roll through that day.

Called for 40 cm of snow changing to rain. Got about 20 while on the road and the rest in rain.

Truck didn't care either way. Just motored right on through...
 
Good little blurb:

GM 6.5L engine

The distributor type Stanadyne injection pump on the GM 6.5L engine regulates fuel quantity with a solenoid valve controlling the amount of low pressure fuel entering the high pressure pumping chamber. The solenoid driver on the side of the pump housing operates the solenoid on command from the PCM, much like gasoline injection. The solenoid is not pulsed, but fully opened and fully closed. The driver senses when the solenoid is fully closed to tell the PCM when injection has ended.

With this system, there is no mechanical governor, no lever, cable or linkage connecting the accelerator pedal to the pump. A pedal position sensor inside the vehicle, much like a throttle position sensor, supplies data on pedal position and movement to the PCM. It then operates the fuel solenoid accordingly. This drive-by-wire system (sometimes called fly-by-wire because it was first developed for aircraft) is also used on some gasoline engines. As things like traction control and anti-skid control become more common, drive-by-wire may eventually replace direct throttle linkage in all vehicles.

The Accelerator Pedal Position (APP) sensor contains three separate potentiometers, each with its own 5V reference and distinct return signals. The triple redundancy is because this is the one signal the PCM absolutely must have to run the engine. If one or two sensors fail, the vehicle can still be driven but with limited power. The PCM will set a code and turn on the ‘Service Throttle Soon’ light. If all three fail, the engine will run only at idle. Using a scan tool and the diagnostic procedure in the factory service manual, you can look at each APP signal. Further, with a scope you can look for the same drop-outs that would indicate a bad throttle position sensor.

Another unique feature on the Stanadyne pump is the Optical/ Temperature sensor on the pump itself. It consists of a standard thermistor type fuel temperature sensor and two optical pick-ups that share a housing and a 5V reference signal. The optical pick-ups read tone wheels that rotate with the cam ring inside the pump. One pick-up provides a high resolution signal, generating 64 pulses per cylinder firing stroke. Along with fuel temperature and the crankshaft position data, this extremely fine position signal makes it possible to trim the fuel quantity for each individual combustion stroke. The other pick-up has only eight slots and reports pump cam position to locate the start of injection for each cylinder and to index cylinder No. 1. Along with the crankshaft position signal, this information is used for pump timing, idle speed control and other ‘real time’ events in power train control.

Injection pump timing is controlled with a stepper motor on the side of the pump. By changing the position of the cam ring, first movement of the high pressure plunger (plunger lift) can be varied relative to crankshaft position. With mechanical governors, this is a function of hydraulic pressure in the pump housing, increasing with rpm to advance timing as speed increases. On this system, the PCM operates the stepper motor.

Most of the other inputs to the PCM are things you’ve likely seen before, including sensors for coolant temperature, crankshaft position, intake air temperature, barometric pressure or manifold pressure (turbo), vehicle speed, brake switch, A/C, cruise control and the automatic transmission sensors and signals. Outputs include the ‘Service Engine Soon’ and ‘Service Throttle Soon’ lights, A/C, cruise control, glow plug relay, automatic transmission and, of course, the injection pump driver and timing stepper motor. EGR was added to this engine in 1997, using a standard vacuum operated EGR valve and a duty cycled solenoid valve to control the vacuum. Troubleshooting all of these with a scan tool is similar to the procedure for gasoline engines.
Click to expand...
 
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