1984 190D Cylinder 3 Misfires

My 1984 190D 2.2L sounds like it's missing on one cylinder, there is a chuffing sound coming from the tail pipe. There is also a knocking sound that is most easily heard when letting off the throttle.

I did a compression test and all four cylinders were between 420-440 psi which was encouraging. Then I ran two cans of diesel purge through but there was no change, even while the car was running on the diesel purge.

I was able to isolate the problem to cylinder three by cracking open the fuel line. When I did this the knocking (injector nailing?) went away and when I tightened it the sound returned.

A quick bit of history:
My grand father gave this car to my parents so that my siblings and I would have a car to learn to drive on. It worked great for several years until my younger brother took the car to a "mechanic" to have a fuel leak looked at. Something was replaced (I don't know what) in the fuel system and when my brother got the car back it had the problem that I am now trying to fix. The mechanic told my brother that it just had some air in the fuel lines and that it would fix itself. After a few hundred miles the problem didn't go away and the car was parked and sat for almost two years until my parents gave it to me a couple weeks ago.

Side note:
I love this site, the kits and guides are great. One thing I wish though is that I could have access to an electronic copy of the guides I've purchased. It takes a week for things to ship from WA to IN and I don't want to wait a week for a diagnostic guide to arrive and then wait another week for parts to show up after I've used the guide to determine the problem.

Thanks and sorry for the long post!

Forums

Chassis Model Number