I will try to be as complete as possible about the problem. My boss has an 02 7.3 that had a bad cylinder and HPOP. About 1 1/2 years ago he bought a used engine from a junkyard. I did a compression test on the ground and found 2 cylinders with low compression that came up some with a wet test. I am a certified machinist and know that is the sign of ring problems but the junkyard insisted that it was valves and against my judgement the boss listened to the junkyard who told us to install it anyway. I have no way to scan it so we have had to rely on him taking it to shops with a scanner and he has spent more on diagnostics than it would have cost for an autoenginuity tester. Before I put the engine in I tested each glow plug on a battery and watched them heat up. After the install I hooked an ammeter between the battery and each glow plug through the harness to make sure there were no problems with the wires. I hooked the same ammeter between the glow plug relay and the harness to make sure that the relay was working and the rest of the harness was good. It has NEVER started right cold with the used engine. Even now with the night temps getting into the mid to upper 70s it still has to be plugged in. One shop insisted that is glow plugs so he bought the set of glow plugs, the undercover harness and valve cover gaskets. No change. The used engine is an e 99 model so I had to change the intake plenums, the turbo pedestal and turbo from the one out of the truck to the one I installed.When I installed the new glow plugs I did another compression test and 2 cylinders were about 370 and the rest were about 395. I have had a mechanical gauge in the HPO system and the cranking high pressure is as much as 1500 lbs. I don't remember now which set of injectors I put in it. I remember that the used engine had the ad injector in number 8 and the engine I took out didn't. The last time he took it to someone for diagnostics they told him it wouldn't complete the buzz test and the temp sensor is sending a temp signal of -50 degrees to the ecm. It sounds like it is only firing one injector until you crank it for 2 or 3 minutes. I know bad for the starter and batteries.. If it is plugged in it starts quickly but if it isn't it is like it is only firing on 1 cylinder. Where should I go from here?(besides maybe a red stick with a long fuse) Stock truck. No mods.

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I meant AE in number 8 instead of AD.

 

370 is fine for compression, the motor I am running right now is 320-325 and starts fine so long as you wait for the glow plugs first thing in the morning.

Have you checked or replaced the glow plug relay?

Need someway to scan it while cranking, HPO pressures and duty cycle would tell a lot.

 

I checked with the ammeter for current drain between the relay and the harness to make sure that the glow plugs were drawing the right amount of power, My high pressure mechanical gauge tells me the pressure is about 1500 but I don't know what the duty cycle is. One shop told him the IDM is bad but it would seem to me if that were true it wouldn't run at all. It starts fine if it is plugged in. Is it possible that the injectors are hanging and have to be warm to start operating?

 

the injectors dont hang... They could be worn and leaking HPO, but you need to watch both HPO and duty cycle to tell that story.

 

It sounds like I need to get my own scan system to get anywhere. I can't get enough information from the shops he has been taking it to to be of any help. It doesn't sound sensible to me but is there any possibility that the IDM could cause the problem or the temp sensor?

 

Nope. IDM would or could cause an issue, but it would be a constant issue or an intermittent issue. It would not be based on temp or first start of the day.

I would lean to HPO issues or worn injectors or injector O rings.

 

I put new o-rings in recently it hasn't helped.

 

Then that leads me more to worn injectors or a HPO issue. Could be draining back, causing the hard start.

Verify that the GPR is transfering voltage properly.

 

With the ammeter between the relay and the glow plug harness if there was no connection there would be no current flow. I am getting the correct current flow for all 8 glow plugs to be working. Watching the mechanical gauge in the HPO rail I am seeing 1500 psi during cranking mechanical reading. A drain back problem would seem to cause a delay in the high pressure reading coming up.

 

True...

Just take a test light and go from ground to the hot side of the GPR... Then do the same from the cold side with the key on... I know it sounds over simple, but its quick and easy.

Need to know the duty cycle to really rule out the pump.