Power Strokes for Different Folks

Some dealership diesel guys I know say they love working on the 6.0L. Why? Well, the main reason is that most of the time it isn’t too hard to figure out what’s wrong with a 6.0L. The weak links in the chain have all been exposed, and there aren’t that many learning experiences (oddball problems that slap a guy around) that happen on a 6 liter any more.


Twenty years ago, the fine tuning available through electronic controls totally changed the face of diesel technology and brought about a cleaner and more efficient family of diesels – Caterpillar’s HEUI system seemed made to order for the job – with oil and fuel rails cast into the iron cylinder heads, special oil-driven injectors and a dedicated high pressure oil pump with a cleverly designed electronic pressure control and feedback system, a new generation of light truck diesels hit the road, and a family of enthusiasts was born within the year.  At the dealership as a technician, I personally tested the fuel economy on 7.3L PSD equipped trucks and found those to be capable of about 18 mpg albeit without aftermarket modifications.


The 6.0L emerged in 2003 with a PCM controlled oil piston driven Variable Geometry Turbocharger (VGT), more torque and power than the 7.3L, some new sensors, an EGR valve and cooler and a nasty collection of bugs we’ll have a look at later.  Fuel economy on the 6.0L was slightly better than the 7.3L for a conscientious driver. Fuel economy concerns aside, the acceleration and torque on a 6.0L can be pretty astounding for someone who has never driven an electronic diesel.


Came the 6.4L in 2007 – With its Series Sequential Turbocharger System, (consists of one Variable Geometry Turbo (driven by a smart box that can talk back to the PCM) and one fixed turbo, this baby has two EGR coolers and 7 (count ‘em) seven heat exchangers behind the grille.  The 6.4L is similar to the 6.0L but with common rail injection, a fuel cooling system, and about 8 mpg in town.  Not a good truck for buying groceries and hauling the kids to soccer practice, but it’s happening all over the country.



This article is focused on the functional differences and the weak links on these platforms – can’t cover all the weaknesses (particularly not on the early 6.0L), but we’ll take a swipe at it. Some of these bugs are only a memory – some happen somewhere to somebody every single day.



Field Bugs on the 7.3L


Early problems that surfaced on the PSD 7.3L were deteriorating injector o-rings (we could screw the return line cup off and find small black string-like particles), sticking Injection Pressure Regulators (IPR, mounted on the high pressure pump) that could cause power loss, no starts or MIL lights, crummy little glow plug relays that burned out after only a few thousand miles, failing fuel pumps (that two stage mechanical critter in the engine valley), shorted glow plugs that fried harnesses at and under the valve cover.

Dual Mass flywheel problems can feel exactly like an engine skip that comes and goes at will and can really hammer a troubleshooter who hasn’t experienced that anomaly.


PSD equipped Econoline vans tended to let water to pour past the driver side hood hinge hole onto the Injector Driver Module (that pricey box that takes its orders from the PCM and steps the injector control juice up to 115 volts) and cause anything from funky running concerns and a bevy of odd DTCs to a call for the tow hook.


If the cold weather backpressure control piston malfunctioned (there was no wastegate yet) that flapper choked the beast so that it couldn’t breathe well, the most noticeable symptom was a nastily consistent lack of power.


Additional concerns were shorted fuel heaters that would blow a critical fuse and kill the vehicle, bad or intermittent cam sensors.  As the miles wore on, wire connectors would corrode and cause signal and trigger loss.  Low pressure oil system concerns would cause hard starts (empty high pump oil reservoir) or a stall and hard start after a couple hundred feet of travel (stuck relief valve in the oil filter head).  And let’s don’t forget all the running problems caused by failing to change the engine oil, using the wrong kind of engine oil, using off-road diesel, etc.

“Fuel cackle” concerns (an oddly loud diesel sound under load that was abnormal) were dealt with by replacing the #8 injector with a different part number, and technical service bulletins abounded outlining various troubleshooting procedures, not the least of which was a measurement of camshaft end-play for intermittent P0340 codes accompanied by oddball no-starts that wouldn’t go away.


The fuel filter return head vanished in1996.  By the time another year passed, those ingeniously designed Caterpillar mechanical split shot injectors had been installed in quite a few trucks, a maneuver that smoothed and quieted the idle by starting the combustion fire early and then adding a second spray of fuel (first developed for California trucks).


In 1998.5 the second generation 7.3L appeared with an electric fuel pump (it features a 20 second run at key on and a hard to access relay that is behind and below the radio in front of the driver’s right knee), mildly extended crank times (the injectors don’t start clicking until the engine has spun for a few seconds), charge air coolers that required the turbo to be  wastegated for boost control (there are a lot of square inches in those big aluminum tubes, so psi had to be limited), and some models had 50 amp intake air heaters to do away with white smoke concerns.


By and large, the second generation 7.3L had fewer bugs – corroded pin concerns are still an issue at the big valve cover connector feeding the glow plugs and injectors, and that corrosion can show up at the IPR and ICP sensor connectors as well.


Rebuilt injectors can malfunction dreadfully and dump lots of engine oil through their innards into the mix, particularly as remanufactured injectors become remans for a second, third and who knows how many more times.  Leaking low pressure oil pump pickups tubes on a few of these babies gave us aerated oil issues (surges, power loss, etc) that were difficult to fathom, and the little filters hidden in the fuel tank pickup assembly tended to clog on long trips if the tank was trashy.

Exhaust Backpressure Sensor Issues


The EBP sensor is a small $100 transducer that gets its exhaust pressure feed through a small steel pipe and provides input to the PCM – sometimes the feed pipe will clog with soot and must be cleaned out, and in some cases, the EBP sensor can short internally, killing the engine and the PCMs ability to communicate with the scan tool.  If the PCM won’t talk and the truck won’t start, disconnect the EBP just for the heck of it (it won’t cost anything to disconnect it) to see if you hit pay dirt.  The sensor isn’t hard to change.  The oil piston built into the base of the turbocharger operates a plate that can close to create backpressure and heat the engine up faster when ambients are less than forty degrees.  Believe it or not, the sole purpose of that sometimes troublesome setup is to get the heater working sooner.



High Oil Pressure Feedback Check


The ICP sensor or its pin connections on 7.3Ls can fail in such a way to the PCM and fail to report actual oil rail pressure – if the ICP reading less than about 500 psi, the PCM won’t even operate the injectors, and if you disconnect that sensor and try to start the engine, the PCM defaults to a 725 lb reading, effectively bringing the injectors back online if sufficient pressure is there.  So if you have a no-start and you can get the powerplant to come alive by disconnecting the IPR, use your Mag light and have a good look at the connector pins.  Note also that the battery voltage should be above 8 volts or so while cranking, else the PCM won’t operate the injectors then either.


So let’s put feet to what we just read: A simple field test you can do in a no-start situation that won’t hurt anything is to disconnect the Injector Control Pressure sensor (ICP), an exercise that forces the PCM to substitute a default Injector Control Pressure reading. If it starts while reading default pressure, you actually have decent high control oil pressure but bad feedback. If it won’t you don’t have enough pressure and the reason for the lack of pressure has to be found. The high pressure pump puts out a lot of pressure but not much volume and the pressure loss can be anything from a bad Injection control Pressure Regulator (IPR) to a pressure leak at one of the injectors.  In the shop, we blocked first one head and then the other with special tools connected to the pressure lines – that’s a tried and true method of isolating the bank, but we won’t go into that now


Sometimes, removing the valve covers (not an easy job) and observing the little oil exhaust ports on the injectors will offer a clue as to which injector is losing the pressure. If you see one that’s dumping a lot more oil than the rest of them, that injector needs to be replaced, but you’ll need to drain the oil and fuel rails before removing the guilty nozzle, else a lot of liquid will go gurgling into the cylinder when you pull the injector out, and you don’t want that!



6.0L Bugs – Where to Start?


The early 6.0L was so loaded with bugs it would take pages to catalog them all.  That in and of itself was quite amazing in light of the incredible measures ITEC had employed to make the 6.0L as dependable as possible. There were more than twenty quality control test areas each engine had to pass during the assembly process.  For example, for the first few months of production, literally every engine that came off the line was being started and run for eighteen seconds.  Early plans to relax the intensity of the test beds were discarded when the engine gave as many problems as it did. The hydraulic (fuel and oil) and electrical systems were carefully and exhaustively checked for leaks and shorts respectively, but nothing the assembly plant can do can measure up to the crucible of daily field use by a happy camper or dozer-hauling construction guy.


ITEC’s third generation PSD held on to the high pressure oil system but dumped the tried-and-true Caterpillar design for smaller, more precise Siemens injectors, which operate at a little less than half the voltage (slightly less than 50 volts) and with two tiny solenoids operating a spool valve on each injector to control both the opening and the closing of the injector.  The high pressure oil rails on the 6.0L are removable, and screwing out the bracket screws neatly unseats the injectors. The glow plugs are accessible by simply removing the wire bus that feeds them instead of having to jerk the rocker arm covers as was necessary on the 7.3L.

The high pressure oil pump is in the rear of the engine mounted in a reservoir and driven by helical gears spinning between the flywheel and the engine block (tidily sealed in a splash oil chamber), and according to ITEC, the flywheel hub can’t be removed without requiring crankshaft replacement.  The ICP regulator and sensor began their 6.0L career on the high pressure pump housing, which makes them both rather difficult to access in a pickup truck, but a little more than a year later the ICP sensor was moved to the right hand oil rail near the glow plug relay controller, and techs were very appreciative.

As an interesting side note, I spoke with a laboratory engineer at the engine plant who told me that the pistons on a hot 6.0L come with .007 inch of the head after everything has expanded to the max, which is pretty scary when you consider the speed with which all those high-dollar parts are moving.


The split shot injector function on the 6.0L was programmed into the operating strategy rather than mechanically handled the way the Caterpillar nozzles did it, but according to one ITEC engineer I interviewed at the assembly plant, too many of the early Siemens injectors weren’t able to perform rapidly enough to split the fuel shot smoothly, and rough/rolling idle warm, and lack of power cold concerns led the engineers to release a PCM re-flash that did away with the split shot function. The moral of that story is that product variability in the field that can’t be overcome by PCM adaptive learning has to be handled with a reflash (software) or a component (hardware) upgrade. The concerns addressed by removing the split shot were initially addressed by replacing the ICP sensors on problem vehicles with an updated part, but finally the PCM reflash (Ford TSB 03-20-12) was released on October 6 2003.

FACTOID For old diesel buffs:  The pop pressure on 6.0L injectors is 3,100 lbs psi.


The down side of that split-shot killing upgrade was a fuel economy dump that hammered the mpg down to about 13 on a good day, but undoing the reflash wasn’t an option, thanks a lot!


Between the heads on the 6.0L there is a flat deck that rims the high pressure oil pump and oil cooler reservoir chambers, and since those are pressurized chambers, the gaskets under the oil cooler and high pressure oil pumps can leak oil and sometimes do.  Pouring in some dye and pressurizing a warm oil gallery with shop air is the optimum way to find those leaks.


Harness chafing seemed to be the order of the day for many a production cycle.  With wire harnesses as thick as a woman’s wrist and lots of dandy little places for the wires to rub through to the copper, Ford

found the need to publish several pages of photos cataloging harness chafe points on various vehicles that could cause a gaggle of issues too numerous to mention here.


Some people are sticklers for every little thing; one 6.0L owner, a friend of mine that I’ll call ‘Joe Bob’ was up in arms down here in Alabama because he found a minute amount of engine oil puddled in his intercooler hoses, but I was able to calm him down a bit by explaining that the PCV system wafts some oil steam into those passages and when it condenses, a small amount of oil is to be expected there.


“Shut up and enjoy the truck, Joe Bob, there’s nothing wrong with it.” I told him.




EGR System


For Serious PSD Gearheads and Engineers
When EGR rates are being commanded by the PCM and when the engine enters into either one of two particularly specified operating ranges, the PCM program is written to perform an EGR flow check.


At the juncture, EGR flow is estimated based on the difference between the Mass Air Flow (MAF) sensor reading and the total mass air flow calculated by the speed density calculation. The estimated EGR flow is then compared to the expected EGR flow to determine if there is insufficient or excessive flow.

The EGR system on the 6.0L has what looks a lot like a GM EGR valve but it has to be removed with a special tool, and coking problems in the intake and EGR passages run rampant if substandard fuel is pumped through the mill.  Ford’s position is that the system can clean itself up if not totally clogged, but it’ll take a few tanks of good clean fuel to make it happen.  Let us digress to say that the manufacturer’s advice on biofuels is that they are not to be used in excess of 5% of the total blend or driveability problems may occur.  Some biofuel users may disagree.


There’s an important heat exchanger called the EGR cooler on the 6.0L EGR system that cools the exhaust gas as its being recirculated – after all, we’re trying to get rid of NOx, (various compounds from atmospheric nitrogen and oxygen locked together during 2500°F + combustion temps) and since the exhaust is being recirculated to reduce combustion heat, why add hot gas to an already scorching situation?


Incidentally, with the EGR valve open and exhaust gas flowing on a 6.0L, the engine runs so quietly that it doesn’t sound like a diesel, and the PCM may operate the EGR valve even at idle, which is an abnormality for those of us who are more accustomed to gas burner logic.


The first 6.0L EGR system was equipped with a throttle plate to create the pressure differential necessary to make EGR flow. Think about it – if the intake is under boost pressure, how can exhaust gas get in there in sufficient quantity to do any good? The EGR-assisting throttle plate disappeared in late 2004, replaced with an ingenious but not complicated scoop in the EGR supply pipe that naturally forced the exhaust gas into the intake.  Incidentally, Duramax uses a throttle plate for the same reason.  The 6.OL also uses a Mass Airflow Sensor (MAF) as a part of the EGR control feedback monitor.

The throttle plate that disappeared on the 6.0L came back on the 6.4L, but for a different reason. More about that later.



Pedal Pots and Stuff


Let’s digress again for a moment or two to review a critical element of the trusty old 7.3L. No PSD has ever had a throttle cable, and most PSD enthusiasts know that the accelerator pedal on those units has a potentiometer and a backup micro switch that are collectively structured to be a redundant pedal position check. Not a bad idea, especially if you consider the nasty prospect of a runaway.  You don’t have the brakes to stop one of these babies if it thunders into its power curve and out of control!


If the micro switch (called the Idle Validation Switch, or IVS) fails to agree with the reported position of the potentiometer, the 7.3L won’t run above idle.  Ever been there?  The whole pedal assembly has to be replaced if either the sensor or the switch fails. I’ve seen a few of those (saw one a couple of weeks back), and might I suggest at this point that if you’re an avid 7.3L pilot it would be a good idea to keep a new pedal assembly for your truck in that box of goodies along with your extra glow plug relay and fuel filter, especially if you travel a lot. Get the right one for your model year – they changed every couple of years, and there are about 4 different part numbers.  With a 10mm socket you can work the nuts, do the wires and ten minutes later you’re back in the wind.


Now for the 6.0L version: it has three pots on the pedal that are redundant, but to the untrained eye, even on a graph, there’s little rhyme or reason to the voltages – suffice to say that they all have to operate within the parameters expected by the PCM or the engine will only operate at low idle.  Medium duty Ford trucks have a 7.3L type setup with one pot and an IVS.



Speed and Position


On the 6.0L, the crank sensor (CKP) reads speed and position as a notched 60-2 tooth trigger wheel goes whirling past it (Duramax uses a 60-3 wheel, go figure), and the crank sensor doesn’t generally give a lot of trouble, but the camshaft sensor (CMP) reads cam position (for injector timing and misfire detection) from a peg pressed into a hole drilled in the camshaft.  Both these signals are buffered and sent to the FICM to be used for injector operation, so the mill will only spin but not fire if either sensor is offline.


If that camshaft trigger peg gets loose enough to find its way out of the hole and into the oil pan, the cam signal may be lost, so if you’re chasing the reason for an absent cam sensor signal and the wires are okay, and if you’ve replaced that long skinny cam sensor to no avail, be ready to peer into the cam sensor hole with the necessary equipment (light and mirror, borescope, etc.) while somebody bars the engine over – if you see an empty hole instead of a trigger peg, it’s time for the hook and some major surgery.


Incidentally, the misfire monitor doesn’t operate above 750 rpm on a 6.0L because it wouldn’t be accurate anyway, and on a 6.0L (according to the 6.0L OBDII service manual), misfire is defined as a loss of compression, but it’ll take a 3/16 hole or bigger in a piston or valve to trigger a misfire code.


Remember, the old 7.3L didn’t have a crank sensor or an Engine Coolant Temp sensor – it only measured the temperature of the engine oil via an EOT sensor.



Pressures – Fuel and Oil


Fuel Pressure: If the fuel pump (located on the frame in the Horizontal Fuel Conditioning Module) shuts down, the injectors will generally suck fuel to their nozzles all by their own action, but there isn’t much of anything that will destroy a set of injectors faster than a low or no fuel pressure concern, so pay close attention to fuel pressure, which should be from 45 to 55 psi, and there’s an Allen plug on the secondary  filter (out by the engine oil filter up top) where fuel pressure is supposed to be checked with an adapter that feeds the gauge.


Important note:  The electric pump on a 6.0L is very hard to hear, so don’t depend on your ears to determine whether it’s running or not unless you have a mechanic’s stethoscope, and remember that the HFCM has a filter in it as well, so you should keep an eye on it.  Depending on the model year, there’s a plug or a lever on the HFCM to drain the water and/or fuel out of the unit when you’re planning to service the primary filter.


Oil Pressure: The high pressure oil system that drives the injectors on a 6.0L can’t work without lube oil pressure, which comes from the familiar old gerotor style oil pump driven by two flats on the nose of the crankshaft.  The oil pump and its relief valve are both built into the timing cover housing and the relief valve is below and behind the balancer and is fairly accessible.  If you screw the relief valve plug out and the relief valve is stuck in its bore, it’ll shove the spring and plug out of the hole. If it’s not stuck, you can take the plug out without a shove and fish the spring and valve plunger out for inspection.  The valve should slide smoothly in and out of the bore and not have a lot of scoring or marks on it.


Think you may have low oil pressure system concerns?  Here’s the deal:  Screw the oil filter cap off, remove the oil filter, and press the button in the bottom of the oil filter chamber behind the stand pipe to drain that chamber– you should do that anyway to release the dirty oil, and the first time you find it, you’ll remember where it is the next time.  Next, spin the engine over while looking down into the chamber – it should rapidly fill with engine oil. If it doesn’t the engine is either out of oil or you have no lube oil system pressure.  Check the relief valve and if it has shavings fouling it you may as well remove the timing cover and replace the oil pump, but that’s not a job for a home boy.


High Pressure Oil: Among the most recent and numerous problems on newer 6.0Ls, there is an oil line with a quick disconnect that likes to pop off of the branch tube and dump the high oil pressure, which renders the engine inoperative.  The branch tube, a bracket, and a new High Pressure Pump outlet fitting is required, and there’s a TSB. Once again, don’t try to fix this at home – it takes a lot of, training and gumption to straighten this problem out – more time, energy, and toolery than most of us have.



Revisiting a Major Problem


I wrote some time ago about a situation I saw when the 6.0L was brand new and the 2003s were still on the showroom floor. Here’s a short recap.


Marty, a technician friend of mine was checking an early 6.0L with power loss concerns that grew worse until the unit finally stalled and refused to restart.  Disclaimer: Marty is an extremely competent technician, but he’s not a Power Stroke specialist. (The PSD guy was out sick with a virus) Marty’s initial inspection revealed a bad turbocharger.


The turbine shaft was wallowing around on wiped out bearings, and that in and of itself seemed strange with only 2500 miles; the truck wasn’t even due for an oil change yet!  After replacing the turbocharger and then destroying the brand new one in a single 7 mile test drive, Marty pulled the dipstick and found that the crankcase was ridiculously overfull with something that felt more like diesel fuel than engine oil.


Draining the crankcase, Marty found no less than seven gallons of liquid, and it was as thin as sewing machine oil.  The engine bearings probably didn’t suffer enough to matter (who knows for sure?), but turbocharger bearings carrying a turbine/impeller shaft spinning at speeds approaching 100,000 rpm simply won’t survive under lousy lube conditions like this.


Using the block heater to warm the engine (standard procedure for any PSD leak detection process, no matter what fluid is leaking), Marty put dye in the fuel, pressurized the fuel system, and found diesel leaking, not from the o-ring at the base of the injector as he and I had originally supposed, but from the injector body on most of the injectors, effectively dumping fuel into the crankcase.


This problem surfaced on more than a few trucks before Ford and Siemens got the problem straightened out, and most of you guys and gals probably know somebody who experienced this failure or one like it.



Mod Squads


Some 6.0Ls come in skipping and smoking with low compression on certain cylinders, and with the head removed, scars on the cylinder walls have always led the factory folks to call for the engine to be removed, reassembled to be shipped back to the plant, and replaced with a new unit.


One of these episodes I saw involved an engine with some Banks performance modifications, but none of us could say for sure that the Banks hardware/software changes actually caused the trouble, and since Ford wouldn’t pay for exploratory surgery, it was difficult to tell what was going on between the piston and cylinder that caused the scars.  Signs of overfueling due to aftermarket mods are fairly easy to spot with the head removed – the injector spray pattern on piston crowns is far more pronounced on an over-fueled 6.0L and more than a few digital photos of those have been fired off to Ford and ITEC to the chagrin of customers whose warranties were in jeopardy.



One Day During a PDI…


Eddie called for my judgment while he was fighting a new 6.0L truck with almost no miles that would run for about thirty seconds and die – as soon as it died, the Fuel Injector Control Module would stop talking to the PCM.  Switching the key off and rebooting, Eddie could duplicate the concern repeatedly.


In a situation like that when there are other new trucks on waiting to be pre-delivered, an A-B-A swap is viable, but I cautioned Eddie against snatching the FICM from another new truck and plugging it in to the problem vehicle.  If the problem truck had some kind of short circuit or voltage surge condition that destroyed the FICM, the last thing he needed to do was plug a pristine new unit into a truck that might be waiting to eat another expensive electronic box.  So what’s the answer?  Put the suspect bad FICM on a good truck – the bad FICM is a LOT less likely to damage the good truck, but a bad truck usually will destroy a good FICM.


End of that story – the good truck performed like the bad truck with the bad truck’s FICM installed. FICM replaced. Case closed.




EBP – the VGT’s Feedback


The Variable Geometry Turbo relies pretty heavily on the Exhaust Backpressure Transducer, and if you have a surge that you can hear or even feel, try disconnecting the EBP and doing a short test drive.  You’ll probably hear a funky rattling noise in the intake during this exercise, but if the surge goes away, chances are you need a VGT actuator, that little PCM-controlled oil piston that uses engine lube oil pressure to drive a rack and operate the VGT vanes.  Let’s talk for a moment about that VGT.


The Duramax uses basically the same turbocharger as the 6.0L, but is equipped with a vane position sensor that reads the position of an eccentric and feeds that info to that vehicle’s ECM, and I’ve been told that the Duramax turbo uses some stainless steel parts, but I couldn’t verify that piece of data.


The 6.0L has a blind steel plug in that vane position sensor hole and uses the EBP transducer and Manifold Absolute Pressure (MAP) reading for feedback.  When the turbocharger vanes are closed, they slow the exhaust and spray it faster onto the vanes, speeding up the turbocharger and forcing it to act like a smaller unit, a maneuver that effectively eliminates turbo lag and gives the 6.0L that crisp acceleration.  This added backpressure also helps with cab heat cold weather much the same way like the turbo backpressure flapper did on the original 7.3L.  As engine demand increases, the vanes open wider, slowing the turbocharger to protect it while still enabling it to work like a large turbocharger.



Most Recent


Is your cooling system de-gas bottle blowing coolant out when you pull a trailer even though it’s not over filled?  Is your coolant contaminated with engine oil? You may have blown head gaskets or a clogged engine oil cooler, but don’t jump too soon – it takes a real cowboy with the right tools to ferret out the cause.


The engine coolant flow on a 6.0L is through the EGR cooler, then it goes to the engine oil cooler (which is beneath the oil filter). If the engine oil cooler clogs enough to restrict coolant flow then it can eventually burst the EGR cooler.   And here’s a nasty: That repair won’t be a warranty fix if you’ve done performance mods!


Turbocharger seals fail sometimes and blow oil through the intake system – the symptom is a tendency of the charge air cooler hoses to blow off under boost conditions, because the oil mist makes the rubber joints slippery and prone to disconnect in spite of the big clamps.  Jimmy (a graduate of my automotive program) was replacing a turbo today for that very reason.



Not Many Bugs on the 6.4L!


The 6.4L, since it is a common rail system (the troublesome high pressure oil system has been eliminated), has a fuel temperature sensor, a fuel cooler with a dedicated supply of coolant and a PCM controlled pump, and a fuel pressure sensor in the right side common rail.  The head bolts are 16mm as opposed to the old 14mm bolts used on the 6.0L.


The automatic transmission flex plate on 6.4 has two extra bolts and while the helical cut gears between the flywheel and the block look just like the ones used on 6.0L, they are different, and they drive the high pressure fuel pump, which is mounted in the same place where the high pressure oil pump was on the 6.0L.


Visteon makes the radiators on the 6.4L and there have been some leakage concerns. Not counting the fire-from-the-tailpipe issue we all saw on YouTube there are a couple of reflashes for a certain group of trouble codes, a couple of wiring problems and a gurgling noise in the heater core.


The fuel pressure from the HFCM is fairly gentle as it is fed to the engine but it is boosted to killer pressures by the radial piston high pressure pump, which has a solenoid vaguely similar to the ICP regulator on the 6.0L, and it controls the pressure to the injectors.  The injectors contain a stack of piezoelectric disks that shrink .001 inch when energized, and since the same fuel pressure is below the long pintle and above it as well, shrinking the piezo disks bleeds the pressure from above the pintle and allows it to pop.  This kind of fuel control is crazily accurate.


The passages (front of each head) where fuel was fed to the injectors on the 6.0L are actually the return path on the 6.4L, and there are of necessity no check valves in the banjo bolts on this engine, so don’t try to retrofit.


The turbochargers operate in series – one turbo is a low pressure unit and the other is a high pressure turbo, but the VGT on this one is controlled by a smart actuator that is actually cooled by the same pump and cooling system as the fuel itself.  In a word, any turbo angle requested by the PCM is considered by the smart turbo actuator, and if the actuator is too hot, it won’t cooperate until the PCM turns the coolant pump on so the actuator can cool off.


There are two EGR coolers (also in series), a sensor measuring exhaust temperature going into the coolers and another temp sensor on the outbound side of the coolers.  To combat the coking problem, the exhaust gas goes through a miniature catalyst of sorts on its way to the EGR system, and so far that little rascal is doing pretty well.


The particulate filter has to regenerate every so often (the PCM does it actively when passive regeneration doesn’t get the job done) and it uses some extra fuel in the process – that may be why the 6.4L tends to use more fuel than the 6.0L.  Particulate filter regeneration will happen between 100 and 600 miles and won’t last as long if road speed above 38 mph is maintained.  Sensitive customers can feel regeneration taking place, and the PCM’s operating strategies are a bit different during regeneration, which, by the way, is what the throttle plate on the 6.4 is used for.



A Green Conclusion


The 6.4L actually cleans the air as it runs, but it does produce carbon dioxide, the very gas that feeds trees and grass, so it’s kind of hard to understand why the folks that don’t like CO2 are called “Greens.” If they had their way, the carbon dioxide would be gone and the trees and grass would barely be able to survive.


Go figure.




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