Squirrels are my nemisis here. Once I found a bunch of maple leaf "spinner pods" down in the valley of my '97 Powersroke, between the turbo and fuel filter. Wondered how those got there? Next time I drove the truck, it would die every time I turned left.
The squirrels had chewed on the wiring to thing that controlled injection pressure from the High Pressure Oil Pump, the Injection Pressure Regulator. The two bare wires had enough slack and evidently "weight" to them that they would swing and short on each other when I turned left.
I figured it out by standing on my bumper with the hood up, engine running, and moving wires until the truck died. This was
after I had paid a local diesel shop to find the issue. At the time I paid the guy $80, and he gave it back to me un-fixed. "I put my scanner on it, and it didn't show anything wrong, but I guarantee ya it'll die everytime ya turn left."
Geez, tell me something I didn't already know.....
Among the feathered varmints are Starlings, English sparrows and female cowbirds. Cowbirds are the ones that wait for some songbird to leave its nest long enough for the cowbird to deposit an egg. The unsuspecting songbird ends up hatching and feeding the cowbird which has a fast growth rate and big appetite, often leading to the demise of her own offspring. I know it's all part of nature but we have so many cowbirds lately it seems like a little thinning is in order. Politics is off limits here so I will avoid making any comparisons... 
Brand new truck so we took it to Nissan thinking a bearing was failing. $200 later they handed me a ziplock bag filled with acorns and misc sticks, hair, moss, etc. It wasn't warranty since vermin had carried the junk in thru the ducts. I told them I was going to put a grill of ratwire over the intake for the air filter system. He pointed out two other small spaces in front of the windshield beside the wipers, triangle shaped. I cut them to fit there as well. No more problems. Every now and then I'd find something on top of the engine, but the heat would quickly rid us of that issue.
