Powerstrokes HEUI injection system

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Powerstrokes HEUI injection system

Postby westcoastslider » Sun Apr 12, 2009 9:53 am

The powerstroke fuel system is not IDI or common rail. It is HEUI which stands for Hydraulic Electric Unit Injection.

hheynow posted a link that shows the concept. http://moodle.student.cnwl.ac.uk/moodledata_shared/CDX%20eTextbook/dswmedia/fuelSys/diesel/elec/heuidieselinject.html

This link has a good discription and some good pics of Fords HEUI system.
http://www.intellidog.com/dieselmann/injector.htm

The major components are

1.injectors

They are supplied by both fuel and oil rails that run the length of the head. Fuel rail running between 60-70psi. Oil rail running 600-2800psi. The computer tells the injector to open the fuel door and fuel enters pushing the intensifier piston up, the fuel door closes and the oil door opens, the high pressure oil pushes the intensifier piston down creating the injection event, and the whole process starts over.

Unlike IDI injectors which the pop pressure can be altered, the HEUI injectors injection pressure is computer controlled. The variables of the injectors themself are the amount of fuel it can hold/inject and the size of the nozzle, and whether it is a single shot or split shot.

The split shot injectors where something originally used only in cali models to improve emissions. Once Ford went to the SD body style 99+ they all got split shots. The split shot allows a small amount of fuel for pre injection which makes for a more complete burn. Performance hounds tend to ditch the split shots for single shots which are easier to get power out of but really "role coal"(unburnt fuel=BAD).

If anyone has info on different volumes or nozzle types please post it or a link.

2.HPOP (high pressure oil pump)

The HPOP is also something that was changed as the 7.3 progressed. In 99 they went from a 15* to a 17* pump. As I understand it the 15* is fine unless your shooting for 350+ hp. There are also aftermarket performance HPOPs available. These are more for tractor pulling and drag racing than for running veg.

The pressure that the HPOP is putting out is constantly monitored and controlled by the PCM(powertrain control module). The PCM receives a signle from the ICP(injector control pressure) sensor.
THIS IS WHERE YOU CAN CHANGE YOUR INJECTION PRESSURE. DO NOT ALTER PRESSURE UNLESS YOU ARE ABLE TO MONITOR YOUR EGT You can put a resistor in the wire going from the ICP sensor to the PCM. The resistor will trick the computer into thinking the ICP is lower than it is and in turn it will increase pressure. This is a performance mod commonly referred to as the 10k mod. There is much discussion about it at the FTE. Here's a link.
http://www.ford-trucks.com/forums/744058-icp-resistance-mod-results.html

3.Fuel pump

Early PSD(94.5-97) used a two stage mechanical (cam driven) fuel pump. A low pressure pump pulls fuel from the tank and pushes it at about 15 psi threw the filter and into the high pressure side of the pump. There pressure is raised to 65 psi and pushed threw the fuel rail, supplying the injectors, and back to the FPR(fuel pressure regulator). This is not a "dead headed" fuel system like the later PSD is. After time the spring in the FPR can get weak and will drop bellow spec. Getting a new spring or shimming the spring with a bb can restore it to factor spec(this should not be guessed at, check your pressure while under load before and after). Cali models(in an attempt to improve emissions) also used a fuel pulse dampener to even out the pressure coming from the mechanical fuel pump. This pump can stand up to veg use.

The later PSD 99+ use an electric pump which pushes fuel threw a pressure regulator and filter, then into the heads which have no fuel coming out of them, a "dead headed fuel system". This pump has been known to fail from veg use. The older pump can not be fitted to the newer block. The newer PSD block has a block off plate for where the older style mechanical lived and there is no cam lobe to power the pump.

Another little trick you can play on the PCM is to make it thinking the engine oil is cold. The computer advances timing until the oil is up to temp. Putting a resistor in the line going from the EOT(engine oil temp sensor) to the PCM will make the computer think the oils is colder than it is and advance timing. Here's a link.
http://www.ford-trucks.com/forums/781429-c00n-icp-mod-eot-mod-combo.html

Using resistors to fool the PCM is a pretty controversial technique and should be done at your own discretion.
Ideally you could make changes to the programming and not have to use resistors on sensors. If anyone knows of a competent PSD tuner that has spent time writing a program for running veg please let me know.
westcoastslider
 
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Postby tubular031 » Tue Apr 14, 2009 11:06 am

Good info!

some good info about the different injectors can be found here
http://powerstrokenation.com/forums/sho ... hp?t=27539

Also another common thing on the 7.3 PSDs is the forged vs PMR I wish mine were forged :(
http://powerstrokenation.com/forums/sho ... hp?t=27537
01 F350 CCLB SRW

Veggie conversion done!
http://www.burnveg.com/forum/viewtopic.php?t=623
tubular031
 
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Postby westcoastslider » Thu Apr 16, 2009 7:08 am

Nice links. Thanks. I learned a lot from the injector link.

What sticks are you running?
westcoastslider
 
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Postby tubular031 » Thu Apr 16, 2009 8:03 am

westcoastslider wrote:Nice links. Thanks. I learned a lot from the injector link.

What sticks are you running?


Stock :( Ill probably go with some stage 1 singles when mine let go. There has been lots of talk about hybirds lately. you can get some big injectors and tune them low till you get the rest of the stuff to support them. If I had a forged motor, I would be all over 450 to 500 as my goal. But with my PMRs 350 is about all I want to go for :(
01 F350 CCLB SRW

Veggie conversion done!
http://www.burnveg.com/forum/viewtopic.php?t=623
tubular031
 
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Joined: Tue Apr 29, 2008 2:47 pm

Postby hheynow » Mon Apr 20, 2009 4:36 pm

Nice thread. Most of this info I've heard of over the years but it's nice to have it all in one place.

On a side note my injectors are original (309,000 miles) and run great after 25+K WVO miles. The fuel pump does handle WVO well but mine last for only a year. I'm getting good at their replacement.
FOR SALE: 1997 Ford F-350 7.3L PSD - Plant Drive kit
1984 Mercedes Euro 300D NA - Custom two tank
Running on used plant oil and biodiesel since May 2006
hheynow
 
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