2 for 2 DV swaps eliminating nailing injectors now. I finally broke down and installed the Monark nozzles in my injectors. Had them for over a year now and never installed. I've been running Bosch India nozzles and the smoke under load was getting a little absurd. Pulled the injectors, swapped over to the Monark nozzles and carefully balanced them. 1950PSI +/- 25PSI is where I wound up. Great chatter, beautiful spray pattern, no leakdown.
Threw them in the car and went for a drive. Knock-Knock, Who's there? The Diseasel... Welcome back, Injector knock! Checked Cylinder 4, which has been my problem child and made no difference in the noise, if anything it got LOUDER. Went through the rest of the injectors and found #6 was my nailer. LOUD, LOUD nailing. Pulled the injector, pop test was still perfect. 1950 on the nose, beautiful spray, no "peeing", and no leakdown.
Immediately swapped out the DV. Like the one from #4, there was a light ring of wear on the sealing face, no pitting on this one though. Torqued everything down and went for a drive. BAD results. Nailing was even WORSE (to the point of people turning and looking) and now I had a dead cylinder. Checked and it wasn't #6 that was dead or nailing, it was #5. Apparently when I loosened the hard line at the IP, I forgot that the entire DV holder will twist if the lock ring isn't fastened down.
Torqued #5 back down and hooked everything back up. Now remarkably quiet. No more nailing, and surprisingly, the remainder of the idle shake I had is now gone too. For the first time since I've owned the car, the idle is about on par with a 6 cylinder gas engine. Not silky smooth, but to the point that you no longer notice the engine idling. With the windows up you really struggle to tell it's even running.
For those keeping track, I've had NO luck with injectors solving the nailing, but had 2 out of 2 attempts at DV replacement solving my issues.
I'm starting to wonder if the DVs simply wear out and need replacing after x00K miles? The general consensus always seems to state that the IP never wears out, but I simply haven't had that result. I realize that my engine is a tiny fraction of a percentage of all of the OM603 engines out there, but it certainly hasn't been a 'wear-free' experience.
Sort of off topic - for anyone else reading, if you're considering injector nozzles, the Monark nozzles are a massive step up from the Bosch India nozzles. Easier starting, much quieter idle, and significantly improved acceleration. The black smoke on hard acceleration is also SIGNIFICANTLY less. With the 3.5L IP and the Bosch India nozzles, it got to the point where I could smoke out an intersection if I put my foot down hard. My Bosch India nozzles were all popping ~1900 PSI except for one which was 2200PSI for some reason (they were balanced at 1900-1950). 3 of the 6 had poor spray patterns (very narrow spray) and 1 was leaking down internally. Not good for 1 year and ~2500 miles of use on Pump #2.