RPM gauge - delayed

[nicknikolovski]

Hi, I have a 93 318is coupe (M42 engine of course).

I have a slight problem with my RPM gauge on the instrument cluster.

The RPM gauge seems to be delayed in its operation and is really giving me the shits.

What could be causing the RPM gauge delay - is it a failing crank/rpm position sensor? or could it be something else?

Any help would be greatly appreciated. :)

Just for further information - the delay is all the time but worse in gears 3-5.
1st gear and sometimes 2nd gear are the only time the RPM is not delayed.

[Vladi]

Maybe you've got a 6cyl instrument cluster.
Since when has it begun to do that?

[nicknikolovski]

I got the car at about 110,000 miles (180,000 km's) and it only started happening after about 185,000 km's. The following parts have been replaced since I bought the car: Rear Muffler, Idle Control Valve, Radiator, Timing Chain Tensioner, Rocker Cover Gasket, I don't believe any of these parts would have contributed to the problem. But I do remember when it started to do it. That day I left the car outside, it was about 82 F (26 C) outside, I drove the car down the driveway and onto the road, As I increased the engine speed and moved through the gears 1st, 2nd, and by
3rd gear I noticed there was a delay in the RPM gauge. I also read somewhere that the Cluster Board may need replacing. Any ideas?

[nicknikolovski]

Does the tachometer get its signal from the ECM, Crank Position Sensor/RPM Sensor, Alternator or some other part?

Any ideas?