Fuel Injectors for 2003 and Newer HPCR Engines
Frequently Asked Questions
Rail Pressure versus Fuel Mileage
Q: In Issue 63, page 82, writer Joe Donnelly did an article about the 2003 and newer ECMs and reprogramming them using a “Smarty” by MADS Electronics. In that article we are told that added rail pressure does not give mileage gains and is “problematic to injector and injection system durability.” Then on page 110 there was a “Product Showcase” article where we are led to believe that increasing fuel pressure will increase mpg by 7%. What is the story?
A: In theory, it would seem that increasing rail pressure would help mileage, as noted by writer Gary Wescott in his “Product Showcase” about the Edge products’ Mileage Max product on page 110. In practice, neither Marco Castano (owner MADS, electronics/developer of Smarty), Mark Chapple (owner of TST, Cummins engineer for 33 years, developer of Power Kit and PowerMax products), nor I have seen any clear, verifiable mileage increase from raising rail pressure above the stock Cummins curve. Power adders do “cheat” the truck’s overhead console report of fuel mileage, giving falsely high readings because fuel is being added that the computer doesn’t know about. Mark Chapple told me he did see a nice torque increase in the 900-1300 rpm range from added rail pressure that was not achievable to the same extent by adding injection duration. As with some other products and approaches to modifying turbo diesels, “YMMV” in internet slang, or “your mileage may vary.” Remember that the Turbo Diesels with the lowest injection pressures, the First Generation trucks, were renowned for giving good mileage. (Then again, they were only rated at 160 horsepower/400 torque and the truck itself was much lighter.)
Finally, in another one of those all-encompassing articles, see the Turbo Diesel Buyer’s Guide, pages 80-99, “So You Want Fuel Economy,” for the bottom line on YMMV information.
Q: What should I do for preventive maintenance on my 2006 Turbo Diesel? I have heard of many injector problems. Do I need a better fuel filter set up?
A: Here are some general things, my opinions:
• Keep exhaust gas temperatures down; I like to keep EGT under 1300° even though you can get away with a bit higher. Dropping a valve seat is expensive, and that is what usually happens first after a number of high EGT “excursions.”
• Change the oil regularly, using CI4+ rather than the newer spec CJ if possible. I like to change it at 4000-4500 miles.
• Keep rpm under 3000, but don’t lug the engine and drivetrain under high power below 1800rpm.
• If you raise rail pressure with a “box” or program, you should improve fuel filtration; 3 microns is a good level. Otherwise, you will probably be okay with the stock 7 micron Fleetguard filter. I like the FASS for its reliable fuel transfer pump and good filters.
Finding the Bad Injector
Q: My Turbo diesel has a lot of timing rattle noise and rough acceleration around 2000rpm under light throttle. When slowing down, the idle drops down to 500rpm and then recovers.
A: Since the truck is not lighting up the dash with diagnostic trouble codes, it is best to start parts-swapping with the least expensive items. Start with the fuel control actuator (FCA) on the back of the CP3 pump. The FCA is less than $120.
Let’s continue to discuss parts-swapping with the least expensive items. The following is a tip that I picked-up from TDR issue 62 where a TDR member wrote-in with a surging, rough idle and hard start problem. Unfortunately for the owner, he had already replaced the injectors, an expensive repair. The tip: “Try adding a couple of cans of ashless two-stroke oil to the fuel. If it clears up, it’s a defective fuel control actuator (FCA). The oil lubricates the FCA and the engine will idle until the two-stroke oil is depleted. It’s a cheap diagnosis method and only takes the time to run some treated fuel through it.”
To finish the story from Issue 62, “I was told that adding a fuel lube to check the FCA was a test that STAR (Chrysler tech assistance) was using some time ago. A friend who had a Turbo Diesel with a sticking FCA added fuel lube to it by accident and the truck ran fine. After a tank and a half of fuel without the additive, the rough idle, stalling, and stumbling returned. He had problems similar to yours and everyone was telling him it was defective injectors. As long as he kept the fuel additive in the tank, the engine ran fine. He tried different fuel treatments including Marvel Mystery Oil. I read about the fuel lube test, STAR, and the FCA and told him to replace the FCA. He replaced the FCA and the truck has been running like new without any additives.”
The owner tried the two-stroke oil and the engine did not stumble, but it still idled rough. The dealership replaced the FCA and the problem with the engine was solved.
To check individual injectors on the ’03-’05 Turbo Diesels, you could unplug one of the three electrical connectors at the head, while the engine is not running (the wires carry up to 50-volts). Once you see which pair of cylinders is at fault, you can remove the valve cover and remove one pair of wires at a time. Or, you could go right to the individual injector wires. You will get a trouble code, but you can remove it later. Since other injectors may be “weak” the best approach would be to send all six to a Bosch shop like Dynomite Diesel for testing. They are a Bosch dealer and could sell you new injectors as needed. Obviously, unplugging the injector will serve as a diagnostic method only if the electrical solenoid is at fault. If you have a mechanical failure, you would have to plug off one injector at a time or replace one at a time. DDP could test all six for you if that would be more convenient.
Other Injector Symptoms
Q: What are some of the other symptoms that I have an injector-related problem?
A: Often a truck will idle and run rough like it is missing. If it shows a diagnostic trouble code (DTC) P2149-“Fuel Injector Group, 2 Supply Voltage Circuit,” you’ll want to check for a fuel injector solenoid failure or the electrical connection through the valve cover gasket. To check for either problem, the valve cover must be removed.
Disconnect each injector in the bank affected which should be cylinder number 4, 5, and 6 and check the resistance with an ohmmeter. It should check less than 1-ohm and greater than 0 resistance. Look for the odd reading.
Disconnect injector harness outside the valve cover and using an ohmmeter, check each wire for continuity and resistance. The wires should be less than 1 ohm and greater than 0 resistance.
Hard Start = Injector Problem?
Q: I have heard that an engine that is hard to start could signal a looming injector(s) problem. Can you explain?
A: Let’s talk about the long crank issue. This is generally created due to the CP3 injection pump not being able to pump up enough pressure in the common rail to fire the injectors (around 5200psi). The first thing to check is the total fuel return volume to see that it doesn’t exceed about 30 ml during a 10-second crank period. Sometimes you can cure the problem by re-torqueing the fuel delivery tubes. Next, check the individual injectors to see that they are returning only 2-6ml during a 10-second crank period.Any injector with a return volume in the 12-14ml range during a
10-second crank period needs to be replaced. This happens when the check ball wears so that it doesn’t seat correctly which, of course, causes a leak. To confirm the problem, with the engine cold, cap off each injector during cranking and see which one allows the engine to fire up.
I noted that TDR writer Andy Redmond had presented this Q&A back in Issue 66. The following is how he went about the diagnostics and repair:
“Recently, a 2005 truck arrived with a hard starting problem. Other recent repairs included two remanufactured injectors, but shortly after the injectors were installed the owner complained the hard start problem worsened as did his poor fuel economy. The scan tool was connected and no diagnostic trouble codes (DTC’s) were present. The batteries were tested and found to have a good charge. My next step was to monitor actual and desired rail pressure (psi) during the cranking attempts. After several consecutive cranking cycles the scanner showed pressure increasing from 1000 psi to about 4,000 psi at which time the engine started. Why will the truck not crank until a certain pressure level is met? Simple. At low pressure the ECM programming does not command the injector solenoids to energize. A light misfire was observed at engine idle.
“The minimum rail psi for engine start is purposefully not stated. Depending upon the scan tool manufacturer and the ECM programming of desired rail psi, it will vary. Likely much of the variance is due to how quickly the scan tool can respond and display a value. I have not personally observed a truck that would start while cranking with less than 2,000 psi. Usually the range is often 4,300-5,800 on a known well running truck. Chrysler lists the rail operating pressures from 4,321 to 23,206 psi.
I suspected excessive injector return flow. Miller SPX service tool part # 9012 (see photo) was installed into the fuel return port on the right rear side of the fuel filter housing (item 4); then a length of fuel line was routed from the fitting to a five gallon diesel fuel can.
Looking at the 5.9 HPCR (’03-’07) fuel filter assembly:
1. Fuel supply line from the fuel tank to the fuel filter at the quick connect point
2. Fuel return line to fuel tank at quick connect point
3. Banjo bolt location for fuel rail and CP3 to return fuel to the system
4. Banjo bolt location for the fuel injectors to return fuel to the filter/fuel tank
Another length of fuel line was routed from the fuel return line to a calibrated container. The total return flow after the engine idles one minute should be less than 180 ml (6×30 ml as previously sugested). This truck showed 443 ml of fuel after the test. This suggests one or more injectors leaking into the return fuel passages (integral inside the cylinder head); improperly torqued injector connector tube retaining nuts (should be 37 ft-lbs); cracked injector body; or fuel leaking into the cylinders (usually causes white exhaust smoke), etc. The injection lines were removed and the connector tube nuts were retorqued. All of the retaining nuts were under specification, with the two at the recently replaced injectors being significantly less than the desired torque specification. Could the torque on the two injector tubes be the only problem?
The injector return flow test volume specifications/testing procedures have varied by model year and have been updated to include additional testing technique—such as the idle ramp up return test and the no start return test (see 2007, Factory Manual, TSB 14-003-06 and Warranty Bulletin D-05-24).
After the injection lines were reinstalled the return test was again performed. The truck started with fewer cranking attempts to build required rail pressure. But, it still wasn’t right. The engine idled one minute and still returned 325 ml of fuel. Next the injector lines were removed one at the time and the Miller SPX tool # 9011 (see photo) was installed at the rail. The engine will run on five cylinders while one line is blocked. The engine was started for one minute with each line consecutively removed, then reinstalled to test each injector. The calibrated container was closely measured for return fuel after each individual injector was block tested. The reason for this process of elimination is to isolate one or more injectors that have excessive return. Any injector contributing more than 40 ml in one minute is excessive. No single injector seemed to be the major leak source. Therefore, replacement of the other four injectors was recommended. The total return flow returned to less than the 180 ml specification when retested. The truck built rail pressure quickly and started normally. The customer later stated that the “lost” fuel economy returned.
When to Replace Injectors?
Q: My 2004 Turbo Diesel has 198,000 miles, but so far no injector problems. Should I replace the injectors now, or wait until I have a problem? They are expensive.
A: Perhaps some discussion about modes of failure would be in order here. As some feel, if things are fine, you don’t need to change injectors. If you haven’t added power, the mechanical aspects will be fine for a long time. As I mentioned, high exhaust gas temperatures and high rail pressures can cause damage. Cracks in the nozzles or bodies, and wear of the check ball and seat are two problems that can occur. On the other hand, failure of the electrical solenoid can happen any time.
Whether you want to incur cost now is up to you. I have heard of folks paying more for reconditioned injectors than what new ones can be bought for. I have heard of high costs at some shops for replacement, and have seen evidence of poor workmanship, leading to further problems. Therefore, you may have two reasons for performing preventive maintenance. You can choose the mechanic/shop and you can buy the latest, stainless steel injectors. On the other hand, you might be able to continue using your old parts for many more miles. Consider also your usage for the truck. If you take long trips through unpopulated areas, such as in the West, a failure could leave you stranded.
What Does it Cost?
Q: Okay, let’s get to the bottom-line: what is it going to cost to replace the injectors, and can I replace them as needed?
A: In the “Injector Upgrades and Preventing Failures” section of this article I briefly touched on the cost, but let me take this opportunity to be specific.
For the do-it-yourselfer the first time you remove and install an injector(s) can take a full 8-hour day. Subsequent R&I can be done in about 4-5 hours. So, time is money…what is the cost of shop labor in your area? What is your time worth?
Unfortunately it takes almost as long to change only one injector as it does to do all six. All types of intake plumbing, breather assembly, wiring, and injector lines have to be removed. So, outside of a low mileage, one-off kind of situation, or where you have a DTC telling you what to do, if an injector is giving problems and you’ve had a good service life from Day One, I would replace all six injectors at the same time.
Shops and vendors have been investing six-figure sums of money to be able to test injectors. Should you have the time to send out for test, this service is becoming more so available. Injector testing cost about $50-60 per unit.
What about the cost of the replacement injectors?
The editor recently did a search using different engine serial numbers used in years 2003-2009 engines. Interestingly there are only three injector generations. I’ll break those down, along with part numbers, for you:
How much do the injectors cost? On any given day you can search the internet and get price quotes from $300 to over $700 per injector. On any given day you can be bumfuzzled with hype and such by alligator-this and hot rod-that shops that claim to sell injectors. On any given day there is a shop or vendor that has invested six-figure sums of money for Bosch test stand equipment to check, test and remanufacture these injectors. On any given day there may be a short supply of injector units.
If you need injectors you’ll want to deal with reputable sales agents. For your consideration: Mopar, Cummins, Cummins ReCon, Bosch accredited shops as recognized by the Association of Diesel Specialist (www.diesel.org, page 137, TDR vendors and specialty shops.
Did you want a performance upgrade injector with your order, sir? How about an order of fries or a hot apple pie? (My attempt at being cute…)
Stock or Aftermarket Injectors
Q: What is better, stock or aftermarket injectors to replace my leaking injectors? Can I replace them myself?
A: Dynomite Diesel has the Bosch injector testing equipment and gets the new stainless steel bodies when they get new injectors from Bosch. They recommend the Stage 1 over stock for performance and mileage. That is what I put into my Turbo Diesel recently. They provide complete installation instructions with color photos with their injectors. For the “how to” on injector replacement, I’ve updated the instructions that I wrote five-years ago in Issue 51 at the end of this article. Be sure the seating nipple end of the connecting tubes are smooth and are seated uniformly, and that the injector line ends are also smooth and corrosion free.
For further discussion on the Dynomite Diesel injectors you’ll want to reread the detailed articles in Issue 66, page 46; Issue 60, page 84; Issue 59, page 86; Issue 57, page 45; Issue 56, page 96.
In Part Six, we have a look at injector removal and replacement.
Principle of Operation | Related Discussion in Previous Magazines & Aftermarket Processes
Upgrades and Preventing Failures | Inside the Injector & The Fuel Transfer Pump
Frequently Asked Questions | Injector Removal and Replacement