Tach gets stuck at 3krpm

[e30Matt]

Sometimes when I crank up the 325 the tach sticks at 3krpm and stays there. After driving for some time it will eventually "un-stick" itself, however, and return to working order.

Anyone got any ideas? Maybe SI batteries?

Also, slightly OT, but my speedo reads about 5mph high, while the OBC is dead-on. Any ideas? Do they get their speed readings from the same sensor?

Ex. Speedo reads 50 while OBC shows 45 after resetting average MPH.

I tested it pacing a friend on the road, the OBC number is right.

[Jordan]

Speedo is off. Adjust the trim pot until its not.

My bet is the tach needle is getting stuck against the clear plastic cover. Had the needle off lately? Maybe you didnt put it on all the way.

[e30Matt]

Tach needle isn't hitting the plastic cover... it's still got plenty of clearance. Any other ideas? Maybe the motor going bad in it?

As for the trim pot, it's located on the back of the cluster, right?

[e9nine]

HOw's your mpg needle behavior? Do you have a spare cluster? Sounds like it could be SI battery related?

[e30Matt]

HOw's your mpg needle behavior? Do you have a spare cluster? Sounds like it could be SI battery related?

All the other gauges behave like they should, except when I start the engine, the needle on the tach goes up to 3k and sticks there. After driving for some time, it'll unstick itself and work fine.