Engine/Transmission (1998.5 - 2002) Tach Bouncing

[JPLB22]

When my truck is idleing in park the tach seems to bounce

about 20 - 50 rpms. When I put the truck in to drive the tach

becomes rock solid. It has done this since day one. I now

have 17,000 miles. Is it normal, or is it LP.

 

[ToolManTimTaylor]

Normal. Mine swings and By the Blue chip display she is Rock steady +- 2 rpm.

 

[dieselsam59]

My H. O. 6-speed does the same at idle No Worrys

 

[pwr2tow]

As long as you do not have a power loss it is normal.



Ron

 

[JR2]

The reason the tach bounces is that the dash is sent data via the ODB2 network in the truck. This is a fairly slow system and aparently the tach starts droping off just as it gets the next update... so it bounces.



There are other reasons for the bounce, ie bad crank/cam sensor but these manifest themselves in other ways too, not just the hoppy tach.

 

[JPLB22]

Thank you for the replies. With all the LP problems I read about I was little worried. But not anymore!!