High RPM 2000 and up the engine just stutters is what it sounds like hot or cold. filters and screens clean, fuel press. good, tried a new cam sensor, cleaned and checked connections at battery, thought we had found it when we cleaned the ground fire wall stud, it stopped for a day here in the shop next morning we went to working on the dash "bad connection on the middle plug" and the stutter was back. when we first started on this we saw that the gauges werent reading correctly or at all but if the tach was showing low rpm the engine would run fine but let the tach read higher rpm the engine would stutter. At any time the tach was not showing the correct rpm it was just where the needle happen to rest. Happen to cut the key off and back on while engine was running and the stutter goes away and doesnt come back until you restart. Got the dash working but the stutter still is there sometimes worse than others some times not at all but the stutter will go away by cutting the key on and off. It did have a code for the cam sensor ground wire but this went away after cleaning grounds. Any thoughts would be great.
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At this point, I would try to remove the tach from the gauge cluster. Do you have the 3 boxes, predecessor to the DLCM? I recall that they would do all sorts of stupid stuff, take it all apart troubleshooting, put it back together and they'd run like it never had issue. Under the dash, should be some buss bars. They look like connections but have no other end. There are metal strips inside which short several terminals together instead of all hanging off one screw. They are color coded, don't mix them up. Check them for corrosion. Those cabs weren't exactly water tight. Good luck n your search.
Do you have the 3 boxes, predecessor to the DLCM . Im not sure what your saying here. Checking the BB connections now. We just ran it with the dash completely disconnected and oil line capped and it sounds the same but worse and at a lower RPM
3 boxes means VPM, ECM & IDM vs the later diamond logic module which was mounted proudly on the side of the DT466 & on the valve cover of the T444E
There is a "Clean Power Harness" that runs from the batteries to the ECM and IDM. It consists of three wires two power and a ground. It has two fuse holders feeding the two power wires. Check the fuse holders for loosing their grip on the fuses. I have found them starting to melt the plastic. Cut all the zip ties and inspect the harness from the batteries up to the IDM and ECM and all the connections on the power harness. Its not uncommon for the power wires to rub through and corrode away. The pass-through connector at the valve cover can have the locks on the outer plug wear away and start making an intermittent connection with vibration. Here is the diagram for the engine power:
Here is a link to the wiring manual for your truck. 96 DT466E.pdf drive.google.com
10.4 will check that wiring mekanik FWF this doesnt have the ECM on the side of engine its over the top of engine coming off firewall by the 2 relays so it must be the 3 version
Navistar called it an IDM, ford called it a FICM. There is a test procedure for it, gonna have to youtube or Google it. Common problem back then. They can be repaired. If that turns out to be your issue.
10/4
Update : wiring, relays, connections and dash all check out now. But problem still persisted and now we had the code 143-2 come back .Customer had already changed the cam sensor with one from a parts place and so had we. So we ordered one thru dealer with shims as it had none on it and customer didnt remember if it did or didnt have any and right off the bat noticed the OEM was clocked different in the metal mount, installed and noticed a difference in the engine. Did some measuring and ended up with .010 shim and it fixed the fluttering. Was wandering if anyone knows if the cam sensors are different between the 3 box and a 1 box and since this was ordered by S/N for a 3 box this could have been the problem. Dont know what brand the customer installed but the first one that we installed was from a truck parts place but was a Ford OEM part.