Temp gauge dancing, stays low (1/4 mark), idle issues

[arcter]

Hey guys. I've got a bunch of little annoying problems going on at the moment.

For one thing, the coolant temp gauge bounces all around. I tightened the nut on the cluster and it still does it.

The temperature is usually also quite cold - or at least it says so. Like 1/4 mark or a little more on the highway, after having been run for quite some time. Hardly ever goes towards the middle.

I recently had my radiator replaced. I also had the thermostat replaced a couple months ago.

The idling issues are strange. When the car is cold (just started up), the idle will be just a tiny bit over 500. Any time I let of the gas and push in the clutch, the idle drops really low like it's going to stall. After warming up, it gets better.

OH also, I've noticed a surging idle when sitting at a stoplight every once in a while. It'll be idling at 700 or so and then surge up to about 1K, and drop back down.

Any ideas? :confused:

[BlueBMW]

Could just be the temp sensor for the cluster is being a little lazy or flaky.  I had one that had got some coolant in the sensor connection and make all sorts of crazy signals back to the cluster.  

For the idle issue, I sometimes have similar and I'm thinking its a lazy idle control valve.  You could pop it off and try cleaning it to see if it makes a difference.

My car also will idle at 1K at times but not all the time.

I suppose you could try a hotter thermostat to try and bring your temperature up a bit.

Where are you located?

[Sarstan]

As far as the idle, you might have some small cracks in your air intake hose.  I know mine has a nice crack near the connection to the engine (past the sensor) and putting duct tape on it instantly stabilized the idle and cured the stuttering.  Just a possibility to check out there.

[locknload]

I have exactly the same issues with mine, I just live with it.  Mine was running cool, new Tstat fixed that, but then the gauge got the palsy.  You may just have a bad temp sensor or loose connection (located left side of head, forward).  It's also possible it can be fixed by replacing the SI board battery, as a lot of instrument maladies have been traced to that.  As far as the idle thing goes, try turning on your A/C and see if that has any effect.  It should bump up the idle a bit and keep it from stalling until you can figure out what the problem is.

[fliplap]

Sorry to return a thread from the dead, but this is driving me nuts too.

My temp gauge does exactly the same thing, and I've checked the nut on the back of the gauge as well. I've also recently replaced the radiator and thermostat.

Did you ever find a fix?

[DesktopDave]

I'm windering if these are a bad gauge or low temp.  Anything electrical is suspect over 20 years.  I'll look up temp sensor specs in the Bentley later.

[bmwm42]

having the same issue on mine with the low temp just going above the blue staying at the first line it idles perfectly but just wont get to the middle have new si board radiator and termostat if this is normal great if not a solution would be appreciated