Hello, not sure where to post this - last couple of days the rev counter needle on my MK1 1.8 has been intermittently settling below normal revs or bouncing slightly. The car usually idles around the 800RPM mark stopped in traffic but the needle has been going to 400 or even lower, then bouncing a little before getting back to normal later in the journey - there is no effect on running and the engine tone does not change, I was thinking bad connection but don’t know where to start.
I am hoping for a low cost explanation but obviously am worried [*-)] that the dial / instrument pod or similar is on the way out - any advice or pointers very much appreciated.
I think it’s a symptom of a bad earth connection. I had that effect intermittently when I forgot to tighten the earth stud just below and inboard of the throttle body. Might be worth checking that one and another just below the washer bottle.
Thanks for the info from you both - it was OK this morning and tonight so will follow your suggestions and will have a good look tomorrow when its light, not slackened anything off recently but did have the rear heater hoses replaced in October and had to explain to the garage that access was by removing the coil pack from the head (I got them to do it as the hose went 1 day after getting them to service the car and change the belts) could be a place to start for bad earth and then track through the suggestions.
Just to say thanks again for the suggestions ref bad earth for rev pointer, hopefully its Ok now - I undid the earth studs and connections in a couple of places near the washer bottle and ledge in engine bay - basically just “broke” the joint a couple of times slackening and tightening and added a bit of WD40 to all visible connectors around the engine bay - no repeat performance yet so have fingers crossed.
