What could be causing this?

[McGyver]

never mind the commercial, but notice how the tachometer is bouncing while i am driving at a constant 65mph in 5th gear? The temp gauge is also fluttering and the "econ-o-meter" is saying i am getting better gas mileage than a prius coasting down a hill turned off. could this be SI batteries or what? thanks for the help!

[Imagine_M]

Sounds like a ground issue

[McGyver]

i forgot to mention that this only happens on the right side of the cluster, and only from time to time. Sometimes everything works, and usually only the tach bounces. Last week the back lights on that side went out, but the next night it worked?

[McGyver]

so no one has any ideas other than grounding?

[Asbradley21]

Check all the connections on the back.

[lateracer]

I've got the same thing going on in my 89 325ic, but on the temp gauge primarily (I get the jumpy tach and funky mileage gauge as well). Thinking it's a ground, but not sure. My gauges stabilize every now and then, but usually jump around most of the time.

I seem to have some other grounding issues in my steering column/dash somewhere(s) (intermittent wiper working, intermittent blinkers working) and I'm hoping that cleaning up all my ground points and connections will take care of all of this.

Let us know if you figure your situation out.

[Adrian_Visser]

The economy gauge going to zero when you let your foot off the gas is correct that's actually how much gas you're burning when your foot is off the gas. The injectors are in fact not injecting any fuel.

[IDM]

Could be the mother board in the cluster acting up. Bang it a couple times to see if it straightens out.

[lateracer]

The economy gauge going to zero when you let your foot off the gas is correct that's actually how much gas you're burning when your foot is off the gas. The injectors are in fact not injecting any fuel.

He's pushing the gas in the video and the economy gauge is still pegged out.

Are you sure the injectors stop sending fuel when you take your foot off the pedal? If that's the case, how does the engine continue to run?

[McGyver]

I've got the same thing going on in my 89 325ic, but on the temp gauge primarily.

I seem to have some other grounding issues in my steering column/dash somewhere(s) (intermittent wiper working, intermittent blinkers working) and I'm hoping that cleaning up all my ground points and connections will take care of all of this.

Could it be an '89 cabrio thing? don't tell me yours is brozit too, cuz that might just be the problem. Everything else appears to be working fine (the spedo reads slow though). So i'll see what i can do about checking grounds.

The economy gauge going to zero when you let your foot off the gas is correct that's actually how much gas you're burning when your foot is off the gas. The injectors are in fact not injecting any fuel.

this was driving up a slight hill at 65mph in 5th gear.

Could be the mother board in the cluster acting up. Bang it a couple times to see if it straightens out.

Believe me, I've hit the dash and that doesn't do squat.

[87-325ic]

smack the top of the dash. it should fix it. it is most likely a loose ground in the back.