OE Tach on 2000 Merc MTY 5.0 acting erratic. Jumps around while driving
drops to 100-200 RPM at idle, but actual RPM's not noticibly lower. Kin of seems like its almost twitching, and fading away so to speak. I there a sensor involved that I can check, or am I going to have t dismantle my dash? Also, is it possible that the TPS sensor o something like that might be starting to go? No service engine light on either..78k miles.
Anyone have any experience with this type of issue
-- MACE
Have had a similar issue on my '96 Explorer XLT. Mine usually jumps up, not down, with no noticeable change in actual engine RPM. Am thinking it has something to do with the in-dash parts as a good whack on top of the dash board (the old fix it with a hammer trick) usually settles it down for a while. When I pull the instrument cluster to replace some burned out bulbs I'm going to do some snooping around and see if I can spot any loose connections or broken solder joints. Mine's been doing it for a couple of years now, hasn't gotten any worse, nor any better either. I notice it mostly on the highway, when I glance down and happen to see the needle jump up or down, likely because familiarity tells me where the tach should be at that speed. But have seen it do the same thing in park at idle.
Steve
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