[Vwdiesel] TD Injection Pump fuelling enrichment

[Milt Kaplan]

Recently I made a 400 mile trip in my 81 pickup Camper with the transplanted Jetta 1.6 TD engine. Its a camper so weight probably similar to Westfalia diesel version. Recent trip netted about 25mpg, remember this is a heavy vehicle with wind drag. I try to drive in 5th on highway as much as possible since engine is quieter. But watching the Isspro EGT pyrometer gauge in 5th, pointer often heads for red zone and I get the smoke effect. Is the resulting smoke the cause of temp heading into red zone? This can't be good for fuel mileage. 
 
1. Should I just drive around in 4th at expense of noise? EGT gauge temp is always lower in 4th gear and don't see smoke. 
 
 2. How about shutting off injection pump enrichment when in 5th gear? Would like to avoid downshifting to 4th. 
 
3. Is the amount of added fuel enrichment based on the turbo boost pressure?
 
4. Perhaps I am looking for Ecodiesel TD performance when in 5th gear?