Rpm's all over the place and throwing codes

[basilry]

Recently my trucks rpm gage has been all over the place from running way to high to running was to low. It has also thrown the codes of P0148 for fuel delivery error and P0299 Turbo underboost. Are these codes related to my tach not working right? It has put the truck into limp mode too. I tryed to clean the sensor that is reading off the dampner thinking that there was some road debris on it but that didnt seem to do any good. Do I replace the cam sensor or is there something more? Anyone come across this before? I also set my attitude to read rpm and that is reading right about where it should be. Does anyone know where the att gets its signal from vs the stock tach?

 

[jelag]

The sensor works on a hall effect system... . there is nothing to clean there are no moving parts... it all has to do with magnetic lines of force when the moving part breaks the magnetic field...

I've got 4 trucks... . and for the most part of close to 500K miles on the group, we've had very few problems... much less than the problems with the Fords we replaced... .

 

[daytripper63]

My truck did that years ago and the Crank position sensor was failing



P. S. The tach gets it's signal from the Crank position sensor