Tractorman

First, I must commend you for a well written description of the symptoms of a problem that you are trying to resolve. People rarely give that attention to detail when describing a symptom or communicating the order of what they have done to resolve the issue. Well done! So, it is interesting that the noise goes away completely with the VP44 running on its own (no ECM communication) and then when the ECM is back in operation, the delayed return of the sound after you inhibit any single cylinder. I don't have the answer, but the fellow you referred to in the above quote may be on to something here. The VP44 has an internal encoder that replicates and compares the crank / cam sensor signal, which could explain why the noise is gone when the ECM is out of the loop (the VP44 no longer needs the crank / cam sensor). And, maybe, when you inhibit a cylinder there is a delay in the knock returning possibly because the timing shifted from the internal encoder to the crank / cam sensor? Just speculating here. Another very good possibility is that if your truck uses a crank sensor, the ring on the flywheel that triggers the sensor may be loose, cracked, or partly missing. John

I have not experienced your situation, but from what I have read from related past postings on this site, you are in need of a rebuilt ECM. The ECM basically will not boot up, or won't finish booting up, so no engine start. John

Don't have any answers, just waiting to see what the APPS reset offers. It will be interesting to see if the Quadzilla is the culprit. John

If you don't mind a few questions after you have had some time in the seat, I would like to know a few things regarding transmission converter lockup / exhaust brake operation under certain driving conditions. Enjoy the truck - I'm sure it is going tow effortlessly. John

Just read this. I would imagine that Mark thought that the end of his world had arrived when that event happened. I'm glad to hear that he didn't suffer any major injuries, or worse. I cannot offer any immediate help for the next two weeks, but after that, let me know if there is something that I can do. I do have a small excavator (about 3500 lbs and it has a thumb) and a dump trailer that I could use to work through the debris, but the excavator would not be able to handle large rocks - say, over 500 lbs. I could scoot some bigger rocks around, just won't be able to lift them. Is your house in any danger of a similar slide? John

Good to hear you are back up and running. Good timing to reseal the vacuum pump and the side cover. I would be very interested in hearing your thoughts regarding the 2025 Ram 8 spd transmission after you drive it for awhile. Are using the new Ram for your upcoming trip? John

An air intake leak on a diesel powered engine of this era will not affect engine idle or cause the engine to die. This is because fuel is directly injected into the engine cylinder - the engine won't care where the air came from. An intake leak could cause poor performance under load because of loss of boost and it will allow unfiltered air to enter the engine which can cause engine damage over time. An air intake leak on a gasoline powered engine will affect engine idle or cause the engine to die because the leak would alter the air to fuel ratio in the intake manifold. John

That would be the one. I still have all of the original positive cables and ground cables on my truck. Periodically, I perform a voltage drop test (using the starter as a load) and I check each circuit individually. In my opinion, a voltage drop test is the best way to determine if an electrical circuit is in good condition. It is conclusive and never lies, and it stops you from wasting time and spending money on unneeded parts. The best part is that you don't have to take anything apart to perform the test, which is really the way you want to do it - actual circuit operation in real time, nothing disturbed. I am also using the OEM alternator (a Bosch). No matter which alternator you use, there is always some AC ripple. Good batteries and good wiring practices absorb that ripple to the point it does not interfere with electronic devices. I have had a few conversations with W-T (a very knowledge man when it comes electricity). The primary reason he installed a Nations alternator was because it uses twice the number of diodes. That was important to him because he is an avid ham radio operator and he really needed clean electrical circuits. He even took apart his lift pump (the worst contributor of electrical noise) and added components to filter the noise. Personally, I wouldn't go to the expense of the Mechman alternator and wiring kit - I would just perform the voltage drop tests and replace any cable or clean any connection that showed excessive voltage drop. John

First, I misinterpreted your numbers. I thought they were readings in the whole number and decimal form. I see now that they are the wire number and a reading in decimal form. Those numbers are good. Yes, these are the relevant wires. The DTC that was set referred to the Idle Validation circuit. As I was typing, you were replying. The wiring circuit looks to be good. Did you re-check Splice #165 for a proper ground (from Pin # 11 on the ECM)? I suspect that the symptoms will resurface. John

If you checking just the wiring harness only (APPS and ECM both disconnected), those readings should be around 1 ohm or less. Did you verify for accurate readings by testing your leads on your multi-meter first? John

I checked Rock Auto and I see that they are genuine Bosch OEM injectors. I don't think the problem is injectors. You do need to get this figured out as you don't want your wife to have to spend too much time in a ravine with an old Beetle. John

My wife and I will be returning from a local camping trip on Friday, June 6. If your trip to Baker City will put you here after June 6th, you are invited to our house and you could stay in a private camp site with water and electrical hookups. You could then tour the areas that you want to see at your leisure. We would be happy to meet a member of the forum and help out if we can. Think it over - you can private message anytime you want. I also have been turning wrenches most of my life, and have a shop and plenty of tools should they be needed. John

They are stock OEM injectors - correct? John

Only 128,000 miles on the truck? What year is the truck? The fuel pump relay that I am referring to is for the VP44 injection pump. It supplies power directly to the fuel solenoid inside the VP44. It is labeled "Fuel Pump" or "Fuel Pump Relay" and it is located in the PDC. The OEM lift pumps are not relayed - they receive power directly from the ECM. I am the original owner of my truck. I started having problems with the VP44 (P2016 code) at 65,000 miles. A year later at 87,000 miles, I had the VP44 replaced under warranty. Additionally, a relayed lift pump was fitted into the fuel tank, also covered under warranty. I have since logged over 310,000 miles on the re-manufactured VP44. Also, worth mentioning is that for the last 310,000 miles, lift pump pressure has never been over 12 psi and usually averages about 5-6 psi, so lift pump pressure really has never been causing the problems with the VP44. Assuming your VP44 has failed and you are running the original VP44, there really is / was nothing you were going to be able to do to make your VP44 last longer. There was a lot of misconceptions regarding the VP44 injection pump failures in the early years and those misconceptions have carried on through the years. The lift pump was the least of the problems, or not even a problem at all. Bosch recognized that there were issues with the early VP44's. Some of those were: rotors not de-burred properly during manufacturing resulting in rotor seizure, poor solder connections in the PSG, under-designed diaphragm for absorbing high frequency pulses, metallurgy problems with timing piston / bore, to name a few. The good part is that Bosch corrected all of those issues with many revisions during their VP44 re-manufacturing process. Unfortunately, other re-builders became involved, but did not necessarily follow through with the Bosch updates. That resulted in casting a continued dark shadow over the VP44 injection pump reliability. From an authorized Bosch re-builder, the Bosch re-manufactured pump comes with a new PSG calibrated to the pump. The combined unit is operated on the Bosch 815 test stand for three or four hours of rigorous testing. This is the pump you want to buy. They have proven to be reliable. John

Well, dang! Did you get good life out of the pump? Those three codes narrow things down a bit. By chance, did you try swapping the VP44 pump relay with another like relay? Doesn't cost anything to check. John

I think he said that he did a road force balance on all of the rear tires. John

The VP44 trucks were only made from '98.5 - '02. There could be a discrepancy in some wiring colors, but not likely. Just pick a row that looks like the colors match the pinout row and you will know right away whether or not you are on track. For example, if the LB/BK wire APPS signal from the ECM pin #25 was a different color than the diagram, then the wire will be the same color where it connects to pin #3 on APPS connector. Just be patient - it will begin to make sense. John

That's always a bit confusing to me, as well. I verify by identifying some of the wire colors on the wire connector side to match them with the pin number. This will confirm the orientation for identifying the correct pin number. John

Shown below are the pinouts for the ECM. Perform continuity tests (using the ohmmeter setting) on circuits that you wish to check. Be sure there is NO POWER supplied to any circuit being tested. For example, the APPS communicates only with the ECM. You could perform continuity tests on all of the connecting wires (see bottom photo). John

Also, unplug the ECM and check for any pins that may be pushed back. John

Ok, I understand. That should rule out a torque converter issue. It does make sense that something changed during the replacement of parts. If I recall, you have to move the throttle assembly to the side in order to access all of the injector lines. Is it possible that the throttle is binding and not letting the throttle fully return? If the throttle does not fully return every time, it is possible that the idle validation switch is not activated in the APPS circuit. It must be activated for the ECM to know to take over idling the engine. Engine idle is controlled by the ECM only - no other inputs. John

Don't focus on this. You could be right, but you also could be wrong. Another scenario (mentioned by @Mopar1973Man ) that could cause your issue is a low stall speed transmission torque converter. Larger injectors allow much more fuel to flow, so when the engine comes to idle, the ECM has to cut way back on fuel delivery (not so much with stock injectors). So, things like a low stall speed converter, or engaging the clutch with a manual transmission, can cause idle fluctuations while the ECM tries to correct. John

You asked, "What are the values of the potentiometer that you use? I like that idea quite a bit." Back in 2016, I tried a fixed output resistor of abut 2,200 ohms, but it set a code and I didn't have a scanner at the time to read the fooled temperature. So, I just bought a variable resistor and installed it (trial and error) and it worked. Later I purchased an OBDLink and dialed in the temperature of 143°. It is easy to make the modification - just buy a couple of Deutsch 2-pin connectors with pigtails from Amazon for the wiring. John Here are @Mopar1973Man 's observations.

I think you are correct. I am basing this on the fact that I am using an IAT fooler (potentiometer) that is adjusted to keep the IAT reading at a constant 143°F. I can tell the ECM responds to the setting because it does not advance the timing aggressively, as it does without the IAT fooler. I don't have the high idle switch on my truck. Maybe it would be worth completely removing the high idle switch to see if the symptoms change. John

This photo is of a typical 12 valve engine. No crossover tubes. Fuel line are connected directly to the injectors, so injectors can be shimmed. John