Guys I’m at my wits end with my motor. Installed a used 7.3 into my pickup after the old one developed a nasty knock. No idea on the history of this motor other than it sat for at least 6 months inside a garage. I swapped all of my top end parts over since I know the history on all of them. It missed from the get go. Found the rear 2 rockers where not getting oil out the pushrods. Finally got that taken care of, and it helped the miss a lot but didn’t solve it completely. Motor has 15-20 psi oil pressure idling and close to 50 at highway speed. It misses at an idle and while under load. Motor does run ok and have ok power for the most part. The shaking and vibration drives me nuts though. I’ve messed with timing, put new injectors in, new lifters. Have not changed the ip due to it being a couple years old. I’ve been driving it for about a month now and have noticed when I drive like a granny(no offense) the miss is greatly reduced at idle, but still present at speed and during acceleration. I promise I’m not crazy or imaging things. Any ideas on the root cause of the miss? I’d be happy to provide any other info I might have left out.

 

what Flywheel does it have ? single Mass or Dual Mass and is it the correct one for the engine?

But now seeing what all you have done I wonder if you may have a Buggered Camshaft.
Have you done a Compression check ? that might tell you something (probably not much)

what did you use to set the Dynamic timing ?

 

It’s got a brand new clutch and single mass flywheel that match the 7.3 non turbo. Wednesday it goes in for a compression check. On the timing I just lined the 2 marks up then advanced it in small steps from there just to see what it would do.

 

compression test time maybe;

 

Finally got it in for the compression test. Came back with the lowest at 375 and the highest at 400. Mechanic said that it sounded like the valve train was abnormally noisy and it almost sounded like the valves where floating when the engine was brought down in the rpms. He said he would start with the cam or the lifters. The lifters are brand new mellings lifters so that leaves the cam. My issue is I’ve always heard that roller cams have very little wear issues but it’s been suggested twice in this thread. Was this unique to the idis or have I just heard wrong. And also I would think valve float would be a spring issue not a cam.

 

use a stethoscope to determine which component of the valve train is causing the issue... you can even move injectors to see if the issue moves too

I've seen plenty of worn out Rockers on these engines too.. may even be bent push rods.

Since you stated there was an Oiling Issue is why I suggested Valve Train as possible issue.

and Like I said Compression check might tell you something (probably Not) but one has to start somewhere those are pretty good numbers

 

Roller cams normally last for a LONG time, I would think with compression numbers like that it should be fine unless it was a dud casting (unlikely) or the motor has been rebuilt and the cam had some wear from the previous failure which would most likely be some kind of oiling issue

 

X2 I don't normally see them go bad unless the Lifter keepers Crap out, <<== this was not mentioned as an issue but Oiling was Mentioned

 

you said it had a oil issue. it may have worn the cam down. even bent a push rod as someone else said.