Defeated by the 6.4? SOLVED

[Keith Browning]

Our Fleet department was delivering a 2008 SD with a 6.4L engine that started losing power and stalling while being delivered. It had 21 miles on the odometer. A short road test confirmed erratic loss of power and intermittent stalling which has gotten worse throughout the time it has spent in our service department.

 

I performed the diagnostics as per the codes which leads to PCM replacement as per the PCED.

• P0087 Fuel Rail / system pressure too low
• P2291 ICP too low engine cranking
• Low fuel pressure 5.5-6.5 PSI
• Passes KOEO, KOER (when it stays running) Injector electrical test
• Passes high pressure fuel system test
• Passes all pinpoint tests for P0087
• FRP sensor KOEO voltage is 0.50V on the nose, wiring looks good

Needless to say the PCM did not correct the concern, after verifying the pinpoint tests again a new HPFP was installed. I had a lot of trouble getting the air out of the system but eventually did. The Hot-Line wanted me to check if the engine was creating air in the system which would indicate a leaking injector. No air. In looking at power balance when the engine runs poorly there are no cylinders that show anything that stands out indicating a possible injector of interest.

 

By this time My FSE has been in twice. We have verified that supply fuel pressure stays in specification, inspected the secondary filter standpipe. Engineering recommended that first I replace the secondary filter as they have seen a few filters that were not opening the standpipe valve due to plastic molding issues. No change. I then disconnected the fuel supply line to the HPFP from the filter housing and installed the fuel pressure adapter and verified fuel pressure to the pump which also confirms the fuel pressure regulator is working. There is only a 0.5 Psi drop which is good. We also drove the truck while monitoring pressure there and the test port on the fuel cooler.

 

In playing around with this, looking at PIDS and ramping up the FP_PCV we temporarily regained some power but the engine still stalls and is hard starting. With PCM updates we are no longer able to control the FP_VCV so we couldn't play with that. It seems as though the engine is capable of making fuel pressure but has a hard time maintaining it. In a hail Mary attempt a new FRP was installed. No change.

 

I was informed that there will be someone from Navistar coming in a week or so. These guys really travel self contained with tools, diagnostic equipment and parts?

[Alex Bruene]

Keith, I worked with an FSE for a week for what sounds like about the same concern. He told me that he usually travels with parts and equipment, but coming into Canada makes border crossing difficult, so he came empty handed on my visit. The only thing he brought my way was a bunch of fasteners and gaskets, everthing else we ordered.

[GregKneupper]

I worked with a navistar fse one time for a week. He brought a few items with him to help diag the truck but most of the stuff we used was my own. He did bring quite a bit of the gaskets and all the nuts and bolts you would need for the engine though. We did not use any of them as we keep all of them in stock. Really good guy. Was not afraid to get his hands dirty and helped me do alot of the tear down on the engine.

[rlchv70]

Just a few things to look at:

 

Supply pressure to the HP pump - Is it good under all conditions?

 

Any internal fuel leaks?

 

Have you inspected the fuel rails for blocked passages?

 

Hope this helps.

[BrunoWilimek]

Just curious, but how long did it sit on the lot before being delivered? What does the fuel look/smell like? Did you perform the injector leakdown test(lay all the injectors on the intake, temporarily connected to the old lines and watch for leaks)?

[Keith Browning]

Rich, all good points of interest and we have been honing in on fuel control. We have ruled out any mechanical concerns for the most part. No combustion leaks, no fuel leaks and fuel quality is good.

 

For those of you following this I am now working with a really good guy from Navistar and my FSE keeps in the loop good guy as well. I have had to call on him now three times with some REALLY screwed up vehicles and he now refers to me as his Angel of Death. /forums/images/%%GRAEMLIN_URL%%/smirk.gif

 

Anyhow, after a lot of looking at PIDS we noticed that FRP does not hold steady, the graph kinda surges up and down. We can hear fuel screeching through the orifice in the filter housing(?) and one of the valves on the pump making a similar noise when idle and performance gets wacky. Power balance is a little wavy but no one cylinder is standing out and this is also true with fuel trims. This tells us that whatever is causing the concern is not any one cylinder or bank.

 

Back to FRP which sometimes dips below FRP Desired. In looking at PIDS he determined that fuel volume was the likely cause. It was decided to look at the wiring, specifically the Volume Control Valve. We made a jumper with salvaged wire terminals and removed the pins from the harness at the PCM and the fuel solenoid jumper harness connector. Now the truck starts quickly and runs perfectly, ran it for at least two hours and two road tests. Then we cut open the harness and removed the questionable circuit and inspected it, load tested it and found nothing wrong with it. /forums/images/%%GRAEMLIN_URL%%/frown.gif We even checked the fit of the pins in the hard-shells and slid them on the mating pins to see if there was a poor connection. Nope.

 

For shits and giggles we reinstalled it. Truck runs perfectly with the original wiring reinstalled. Now we are all perplexed. There is talk of the slight possibility of RF interference as the wire was positioned in the loom. My idea but I know little. It was not ruled as impossible though. Obviously we cant return it to its original placement so this is just a theory. RF interference is not a known issue at all from what I gather from conversations. We are deep into unknown territory. A new harness is going in regardless at this point. If the truck continues to run perfectly then we have obviously fixed it but have no solid diagnosis or cause other than to say "it was the harness."

[Keith Browning]

The saga continues. /forums/images/%%GRAEMLIN_URL%%/banghead.gif

 

None of this has made any sense. The Navistar FSM thought it over and re-investigated the fuse box and VBAT circuit and stumbled upon the root cause. Apparently something damaged the fuse pin in the battery junction box. This truck is new, I never touched it and our fleet department didn't touch it either therefore this likely happened sometime during the production process either in vehicle assembly or from the part supplier. We had looked at this before and did not catch the pushed in pin that was also damaged. The final result was reduced amperage capacity due to a poor connection at fuse F74...

 

 

Make note of the uneven and spread terminal. We have all seen this before but this kind of damage usually causes easy to recognize and detectable symptoms.

 

 

A look at the rear of the pin gives you a good idea of how we can have continuity but lack the capacity to handle adequate amperage. No different than a damaged wire with only a strand or two completing the circuit or corroded connections.

 

 

I repaired the terminal and the fuse block, reassembled the vehicle and road tested the truck until we were satisfied that this one was solved and repaired. If you look at the schematic, this fuse supplies battery voltage to the MAF, EGR valve, VGT actuator and the cooling van along with the fuel control solenoids, pressure and volume. These are connected in series using several splices. The fuel control solenoids are probably the last in line to get their power. Apparently, not quite enough for the VCV to function correctly. Here is the odd part that made diagnosis difficult, no codes for the other components on this circuit and all circuit tests passed. Perhaps this is another example to support the concept of load testing circuits, but if you powered a headlamp bulb with this circuit it probably still would have been nice and bright. Do you think this might have shown up with a voltage drop test with the engine running?

Quote:

Voltage drop

From Wikipedia, the free encyclopedia

 

 

Voltage drop is the reduction in voltage in an electrical circuit between the source and load. In electrical wiring national and local electrical codes may set guidelines for maximum voltage drop allowed in a circuit, to ensure reasonable efficiency of distribution and proper operation of electrical equipment (the maximum permitted voltage drop varies from one country to another)[1].

 

Voltage drop may be neglected when the impedance of the interconnecting conductors is small relative to the other components of the circuit.

 

For example, an electric space heater may very well have a resistance of ten ohms, and the wires which supply it may have a resistance of 0.2 ohms, about 2% of the total circuit resistance. This means that 2% of the supplied voltage is actually being lost by the wire itself.

 

Excessive voltage drop will result in unsatisfactory operation of electrical equipment, and represents energy wasted in the wiring system. Voltage drop can also cause damage to electrical motors.

 

In electronic design and power transmission, various techniques are used to compensate for the effect of voltage drop on long circuits or where voltage levels must be accurately maintained. The simplest way to reduce voltage drop is to increase the diameter of the cable between the source and the load which lowers the overall resistance.

 

 

 

 

I have a lot of thoughts about this experience - another topic to come.

[DwayneGorniak]

I had a very similar issue with an )08'. However, my issue wa a check engine light for driver side bank of glow plugs. I was losing the whole bank intermittently. The result was a terminal in the battery junction box that would push down when you installed the fuse. The plastic locking tab in the BJB was broken and when you pull the fuse out, the termonal would sit up properly. But when you would push the fuse back in, it would push the terminal down inside the box. Danged Gremlins! But I will never forget it.

[Brad Clayton]

Aahhhh 'ol fuse #74. I can't wait to see Ford try to boot leg your pictures now. /forums/images/%%GRAEMLIN_URL%%/grin.gif

[rlchv70]

Do you think this might have shown up with a voltage drop test with the engine running?

 

 

I would think so.

[Bruce Amacker]

Good Job! It is problems like this that give great satisfaction once they are solved.

 

 

/forums/images/%%GRAEMLIN_URL%%/thumbup.gif

[Keith Browning]

Brad, they can have them if they need them if they ask. I did leave the Navistar FSM with all of them so I am sure, no, I am positive a few of them are already in the hands of Ford engineering where they should be. THESE photos were intended to be used by the manufacturers.

 

Rich, The thought to check for voltage drop came too late for testing but it would have been interesting.

 

Bruce, there sure is a great deal of satisfaction when one of these nightmares solved. What is better is spending three days with this guy from Navistar. I learned a lot about reading data and interpreting it. Much of it would not have seen for a long time because of the few driveability issues the 6.4L is having. Aside from that Carl is a great guy and a pleasure to have around.