Hey Folks, been piddling around on the 82 NA diesel rabbit I bought. Just sort of going through it and cleaning up odd stuff I don't like.
I added an aftermarket tach today. It's a W-signal tach. Admittedly, I have no way of verifying that the tach is accurate until I get my hands on a handheld, optical tach to read crank RPM and set the W wire tach accurately.
But I digress. Before I installed the tach, I noticed that there seems to be a fuel cut around what my ear says is 3-3500rpms. The car seems to drive fine below 3000rpms. It doesn't seem to be down on power. It seems to start fine after about 10 seconds of glow plugs. No oddities from my perception. The car makes a small amount-whisps out the exhaust- of black smoke at full throttle. Installed the W wire tach today and set it to around 800rpms reading at idle. This is pretty close, ballpark. Revved the car up after it was warm and, sure enough, the engine hits something that is limiting rpms.
It seems to be happening around an unverified 3000-3500rpms. It it, seemingly, for sure below the factory cut that I've read is something like 4500rpms. It is not a "soft" cut. It sounds like fuel is being stopped and then added back, then stopped, rapidly. Sounds pretty much like a spark ignition hitting a factory rev limiter. But it's happening at 3000ish rpms. The motor puffs a small amount of light colored smoke when it taps the max rpm that can be achieved.
I assume, logically, that it has to be something fueling related. I'm ordering a shop manual for injection pump setup info as I type this.
As I'm new to these cars, I don't have a solid foundation of "common issues and how the symptoms present themselves." I figure there's a chance this is something obvious and y'all can pinpoint it immediately.
Anyone have any smart ideas?
Thanks for your time an consideration. Much appreciated!